File No. 1-0023
SA-422
AIRCRAFT ACCIDENT REPORT
SOUTHERN AIRWAYS, INC. DC-9, N97S
Tri-State Airport
Huntington, West Virginia
November 14, 1970
ADOPTED:
A p r i l 14, 1972
NATIONAL TRANSPORTATION SAFETY BOARD
Washington, D. C. 20591
REPORT NUMBER: NTSB-AAR-72-11
T E C H N IC A L REPORT STANDARD TITLE PAGE
1 . Report No.
I 2.Government Accession No. I 3 . R e c i ~ i e n t ' sCatalog" No.
NTSB-A&- 72- 11
I
4. T i t l e and Subtitle Aircraft Accident Report,
5.Report Date
April 14, 1972
Southern Airways, Inc. , DC-9, N97S, Tri-State Airport, ,.
6.Performing Organization
Huntington, West Virginia, November 14, 1970
Code
7 . Author(s)
8. Perform i ng Organ i t a t i on
Report No.
9 . Performing Organization Name and Address
Bureau of Aviation Safety
National Transportation Safety Board
20591
Washington, D. C .
10.Work U n i t No.
1 1 .Contract or Grant No.
13.Type of Report and
Period Covered
Aircraft Accident Report
November 14, 1970
12,Sponsoring Agency Name and Address
NATIONAL TRANSPORTATION SAFETY BOARD
D. C. 20591
Washington,
14.Sponsoring Agency Code
I
15.Supplementary Notes
16 .Abstract
Southern Airways , Inc. , DC-9, N97S , operating as charter Flight 932 , crashed
during a landing attempt a t the T r i - S t a t e Airport, Huntington, West Virginia, a t approximately 1936 e . s . t . , on November 14, 1970. A l l 75 occupants, including 71 passengers and four crewmembers, were f a t a l l y injured. The a i r c r a f t w a s destroyed.
The f l i g h t , chartered t o transport the Marshall University f o o t b a l l team and
boosters from Kinston, North Carolina, t o Huntington, West Virginia, w a s attempting a
nonprecision instrument landing approach t o Runway 11 a t the time of the accident.
The crash occurred following impact with trees on a h i l l approximately 1 mile west of
t h e runway threshold. The elevation of the broken trees a t the i n i t i a l impact s i t e
was approximately 922 f e e t m.s.1.
The National Transportation Safety Board determines t h a t the probable cause of
t h i s accident w a s the descent below Minimum Descent Altitude during a nonprecision
approach under adverse operating conditions, without visual contact with the runway
environment. The Board has been unable t o determine the reason f o r t h i s descent
although the two most l i k e l y explanations are (a) improper use of cockpit instrumentation data, or (b) an altimetry system error.
17. Key Words
18.Distribution Statement
Aircraft accident, charter operation, crew coordination, Released t o Public
Unlimited Distribution
misuse of a l t i t u d e information, vertical guidance i n
nonprecision approaches.
19.Security Classification
(of t h i s report)
UNCLASSIFIED
20.Security Classification
(of t h i s page)
UNCLASSIFIED
ii
21.No. o f Pages
78
22.Price
NATIONAL TRANSPORTATION SAFETY BOARD
Washington, D. C. 20591
r
I
SA-422
File No. 1-0023
AIRCRAFT ACCID NT REPORT
SOUTHERN AIRWAYS, INC. DC-9, N97S
Tri-State Airport
Huntington, West Virginia
November 14, 1970
ADOPTED:
A p r i l 14, 1972
_E _R _R _A -T- A
Please make t h e f o l l o w i n g c o r r e c t i o n s on page 32 o f t h e s u b j e c t r e p o r t :
(1)
I n t h e t a b u l a t i o n a t t h e t o p h a l f o f page under ' T e r r a i n E l e v a t i o n '
and o p p o s i t e ' R o t a t i o n p r i o r t o t r e e impact,' d e l e t e t h e f i g u r e
891.
-
(2)
Footnote
21/
i s changed t o read as f o l l o w s :
A n a l y s i s of a i r c r a f t performance data, t h e f l i g h t d a t a r e c o r d e r ,
and t h e c o c k p i t c o n v e r s a t i o n leads t o t h e c o n c l u s i o n t h a t a i r c r a f t
r o t a t i o n was i n i t i a t e d approximately 2 seconds a f t e r t h e c a l l o u t
a t 400 f e e t . R o t a t i o n took approximately 1.7 seconds. During t h i s
3.7 seconds, t h e a i r c r a f t descended approximately 135 f e e t .
June 14, 1972
REPORT NUMBER: NTSB-AAR-72-11
NATIONAL TRANSPORTATION SAFETY BOARD
Washington, D. C. 20591
SOUTHERN AIRWAYS, INC. DC-9, N97S
Tri-State Airport
Huntington, West Virginia
November 14, 1970
ADOPTED:
April 14, 1972
L
August 31, 1972
REPORT NUMBER: NTSB-AAR-72-11
a l t i m e t e r s i n i n s t r u m e n t a p p r o a c h e s o v e r l e v e l a n d i r r e g u l a r t e r r a i n . Howe v e r , t h e Southern A i r w a y s DC-9 Operating Manual did not m a k e s u c h a
distinction, but r a t h e r a c c e n t u a t e d its u s e f o r a l l i n s t r u m e n t a p p r o a c h e s by
stating t h a t , "Two s e p a r a t e r a d i o a l t i m e t e r s y s t e m s . . . a r e provided to
obtain p r e c i s e altitude i n f o r m a t i o n above the ground a t the minimum d e c i sion [ s i c ] altitude (MDA). This i n f o r m a t i o n is e s s e n t i a l to the pilot i n his
d e c i s i o n to l a n d o r i n i t i a t e a g o - a r o u n d m a n e u v e r . I ' Notwithstanding t h e f a c t
t h a t t h e c r e w m a y have been f o r m a l l y t r a i n e d to u s e the r a d i o a l t i m e t e r a s a
s e c o n d a r y r e f e r e n c e , the tabulation c o m p a r i n g t h e a v a i l a b l e altitude r e f e r e n c e s indicated t h a t the f i r s t o f f i c e r m a y have r e l i e d o n t h e w r i t t e n m a t e r i a l
a n d w a s using t h e r a d i o a l t i m e t e r f o r altitude i n f o r m a t i o n .
If t h e f i r s t o f f i c e r w a s m a k i n g altitude c a l l o u t s by r e f e r e n c e to the
r a d i o a l t i m e t e r , a s hypothesized above, t h e r e m a i n i n g q u e s t i o n c o n c e r n s
the extent to which t h e c a p t a i n r e l i e d upon, a n d w a s m i s l e d by, s u c h callouts.
Sound o p e r a t i n g p r o c e d u r e s d i c t a t e t h a t the c a p t a i n should have been using
h i s b a r o m e t r i c a l t i m e t e r during t h e a p p r o a c h , a n d t h e r e f o r e should have been
a w a r e of t h e d i s p a r i t i e s between a l t i t u d e s r e f l e c t e d by t h a t i n s t r u m e n t and
t h e f i r s t o f f i c e r ' s callouts. Why t h e s e d i s p a r i t i e s w e r e a p p a r e n t l y not d e t e c t e d by t h e c a p t a i n i s difficult to explain. It i s p o s s i b l e t h a t he, l i k e the
f i r s t o f f i c e r , w a s relying on h i s r a d i o a l t i m e t e r . A s e c o n d possibility i s
t h a t h e w a s not using h i s b a r o m e t r i c o r r a d i o a l t i m e t e r , but r a t h e r w a s r e lying s o l e l y on t h e f i r s t o f f i c e r f o r altitude information. Finally, he m a y
have been including h i s b a r o m e t r i c a l t i m e t e r i n h i s i n s t r u m e n t s c a n , but
w a s c o n c e r n e d with o t h e r items during the f i n a l s t a g e s of the a p p r o a c h to
s u c h a n extent t h a t he did not notice any v a r i a t i o n s .
On the o t h e r hand, t h e r e a r e s e v e r a l w e a k n e s s e s to t h e t h e o r y t h a t t!ie
r a d i o a l t i m e t e r w a s being u s e d f o r altitude information. First, a n d p e r h a p s
rrtost i m p o r t a n t , the r a d i o a l t i m e t e r i s not intended f o r u s e d u r i n g a n a p p r o a c h
o v e r unknown o r uneven t e r r a i n , a n d i t is t h e r e f o r e difficult to a c c e p t that
qualified, e x p e r i e n c e d pilots would r e s o r t to t h a t i n s t r u m e n t i n conducting
th,: a p p r o a c h a t Huntington. The t h e o r y a l s o a s s u m e s a n unlikely dual :?urnan
f a i l u r e i n t h a t the c a p t a i n w a s e i t h e r a l s o u s i n g h i s r a d i o a l t i m e t e r o r did
not r e c o g n i z e t h e d i f f e r e n c e s between t h e b a r o m e t r i c a l t i m e t e r a n d t h e
altitude i n f o r m a t i o n c a l l e d by t h e f i r s t o f f i c e r a n d w a s relying a n t h e l a t t e r .
Finally, t h e r a t e s of d e s c e n t between t h e c a l l s of "Seven hundred f e e t , ' I
"Two h u n d r e d above, '' " F o u r hundred, I' a n d rotation, i f m a d e f r o m r e f e r e n c e t o t h e r a d i o a l t i m e t e r , do not c o r r e s p o n d to t h e r a t e s of d e s c e n t r e c o r d e d by t h e flight data r e c o r d e r f o r t h e s a m e p e r i o d s .
This v a r i a t i o n i s d e m o n s t r a t e d i n t h e following calculations. By using
t h e t e r r a i n elevation e s t a b l i s h e d by t h e flightpath a n a l y s i s f o r the position
- 31 -
of t h e a i r c r a f t a t t h e time t h e r e f e r e n c e c a l l s w e r e m a d e , a n d adding t h e s e
c a l l s to t h a t elevation, t h e following tabulation shows (1) t h e first o f f i c e r ' s
callout, (2) t h e flight r e c o r d e r indication, (3) t e r r a i n elevation, and ( 4 )
t h e altitude, i f a r a d i o a l t i m e t e r w a s being u s e d ( t e r r a i n p l u s t h e callout).
Flight
Recorder
Terrain
Elevation
Terrain
P l u s Callout
700 feet
1,330
550
1, 250
200 above
1, 224
530
1,130
400
1,005
690
1,090
Callout
Rotation p r i o r
to t r e e i m p a c t
925
B a s e d o n t h e above points, t h e following rates of d e s c e n t would b e r e q u i r e d :
R a t e s of D e s c e n t ( f e e t / m i n u t e )
F l i g h t Data
Terrain
Recorder
P l u s Callouts
Between C a l l s
"700 f e e t " t o "200 above" (5.2 seconds)
1,223
1,385
11200above" t o "400" (11.4 seconds)
1,153
211
1,297
2,189
"400"
t o point of r o t a t i o n (3.7 seconds)21/
-
I t i s noted t h a t t h e rates of descent c a l c u l a t e d f o r t h e f l i g h t recorder
d a t a a r e i n an increasing p a t t e r n and r e l a t i v e l y c l o s e t o t h e o v e r a l l r a t e
described by t h e f l i g h t recorder. The rates of descent based on t h e calcul a t e d r a d i o alti-meter c a l l o u t s show c l o s e c o r r e l a t i o n f o r t h e i n i t i a l c a l l o u t ,
no c o r r e l a t i o n f o r t h e second c a l l o u t , and i n t h e f i n a l segment, t h e descent
r a t e i s approximately double t h e o v e r a l l r a t e .
A f t e r c a r e f u l l y weighing t h e conflicting points s e t f o r t h above, t h e
B o a r d c o n c l u d e s t h a t t h e t h e o r y u n d e r c o n s i d e r a t i o n - - namely, t h a t t h e
unrecognized d e s c e n t t h r o u g h MDA w a s t h e r e s u l t of u s i n g t h e r a d i o a l t i m e t e r
21/
Analysis of a i r c r a f t performance d a t a , t h e f l i g h t d a t a recorder, and t h e
cockpit conversation leads t o t h e conclusion t h a t a i r c r a f t r o a t a t i o n was
i n i t i a t e d approximately 2 seconds a f t e r t h e c a l l o u t a t 400 f e e t . Rotation
took approximately 1 . 7 seconds. During t h i s 3.7 seconds, t h e a i r c r a f t descended approximately 135 f e e t .
- 32 -
SOUTHERN AIRWAYS. INC., DC.9.
N97S
TRI-STATE AIRPORT. HUNTINGTON. WEST V I R G I N I A
NOVEMBER 14. 1970
TABLE OF CONTENTS
Page
.
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.14
1.15
1.16
2
2.1
2.2
.
3
.
. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
. . ....... .. .. .. .. .. ....... .. .. .. .. .... . .
. . . .. .. .. .. .. .. .. .. .. .. .. .. .. ..
. . ....... .. .. .. ... .......... ... ... ... ......... .. ..
Synopsis
Investigation
History of t h e F l i g h t
I n j u r i e s t o Persons
Damage t o A i r c r a f t
Other Damage
C r e w Information
A i r c r a f t Information
Meteorolo-gical Information
Aids t o Navigation
Communications
Aerodrome and Ground F a c i l i t i e s
F l i g h t Recorders
Wreckage
Fire
Survival Aspects
Tests and Research
Other
Analysis and Conclusions
Analysis
Conclusions
a
Findings
b
Probable Cause
Recomnendations
Append ices
A
I n v e s t i g a t i o n and Hearing
B
C r e w Information
C
A i r c r a f t Information
Excerpts from Cockpit Voice Recorder Tape
D
Effect of S t a t i c System R e s t r i c t i o n or Blockage on
E
Airspeed I n d i c a t i o n
F
A i r Carrier Operations B u l l e t i n No 71-9
G
Safety Recommendations re: A l t i t u d e Warning Device
Attachments
1 F l i g h t p a t h and P r o f i l e
Jeppesen Approach P l a t e s f o r Tri-State Airport
2
Comparison of Descent P r o f i l e and 3O Glide Slope
3
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3
3
5
5
5
5
5
5
8
9
9
10
11
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12
12
15
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21
34
34
36
37
File No, 1-0023
SA-422
NATIONAL TRANSPORTATION S A F E T Y BOARD
WASHINGTON, D. C . 20591
AIRCRAFT ACCIDENT R E P O R T
Adopted:
April 1 4 , 1 9 7 2
SOUTHERN AIRWAYS, I N C . , DC-9, N97S
TRI-STATE A I R P O R T , HUNTINGTON, WEST VIRGINIA
NOVEMBER 14, 1970
SYNOPSIS
Southern A i r w a y s , I n c . , DC-9, N97S, o p e r a t i n g as c h a r t e r
Flight 932, c r a s h e d d u r i n g a landing a t t e m p t at the T r i - S t a t e A i r p o r t ,
Huntington, W e s t V i r g i n i a , at a p p r o x i m a t e l y 1936 e , s. t . , o n N o v e m b e r 14,
1970. A l l 75 o c c u p a n t s , including 71 p a s s e n g e r s and f o u r c r e w m e m b e r s ,
w e r e f a t a l l y injured. The aircraft w a s d e s t r o y e d ,
T h e flight, c h a r t e r e d t o t r a n s p o r t the M a r s h a l l U n i v e r s i t y football
team a n d b o o s t e r s f r o m Kinston, N o r t h C a r o l i n a , t o Huntington, W e s t
Virginia, w a s attempting a n o n p r e c i s i o n i n s t r u m e n t landing a p p r o a c h t o
Runway 11 a t the time of the accident. T h e crash o c c u r r e d following
i m p a c t with trees on a h i l l a p p r o x i m a t e l y 1 mile w e s t of the runway
threshold. The e l e v a t i o n of the b r o k e n t r e e s at the i n i t i a l i m p a c t site
w a s a p p r o x i m a t e l y 922 feet m. s. 1.
T h e M i n i m u m D e s c e n t Altitude, below which d e s c e n t is not
a u t h o r i z e d u n t i l the runway e n v i r o n m e n t is i n sight, f o r this i n s t r u m e n t
a p p r o a c h w a s 1 , 2 4 0 feet m. s. 1.
T h e w e a t h e r at the time of the a c c i d e n t was: 300 feet s c a t t e r e d ,
e s t i m a t e d 500 feet variable b r o k e n , 1, 100 feet o v e r c a s t , visibility five
miles, light r a i n , fog, s m o k e , wind 360° at 4 k n o t s , a l t i m e t e r s e t t i n g
29.67, ceiling r a g g e d and v a r i a b l e 400 t o 600 f e e t .
Probab1,e Cause
The National T r a n s p o r t a t i o n Safety B o a r d d e t e r m i n e s t h a t the
p r o b a b l e c a u s e of this a c c i d e n t w a s the d e s c e n t below Minimum D e s c e n t
Altitude d u r i n g a n o n p r e c i s i o n a p p r o a c h u n d e r a d v e r s e o p e r a t i n g con
ditions, without v i s u a l contact with the runway e n v i r o n m e n t . The
B o a r d h a s b e e n unable to d e t e r m i n e the r e a s o n f o r this d e s c e n b a l t h o u g h
the two m o s t l i k e l y explanations a r e ( a ) i m p r o p e r u s e of cockpit i n s t r u m e n tation d a t a , o r ( b ) a n a l t i m e t r y s y s t e m e r r o r .
-
Recommendations
The Board r e c o m m e n d s that:
1.
All s e g m e n t s of the a v i a t i o n i n d u s t r y continue to focus
a t t e n t i o n on the unique d e m a n d s f o r c r e w coordination
and vigilance d u r i n g n o n p r e c i s i o n a p p r o a c h e s . P a r t i c u lar e m p h a s i s should b e p l a c e d on the a c c e l e r a t e d developm e n t of a r e a navigation s y s t e m s with v e r t i c a l guidance
c a p a b i l i t y and o n h e a d s - u p d i s p l a y s y s t e m s .
2.
The A d m i n i s t r a t o r evaluate the need f o r the i n s t a l l a t i o n
and u s e of ground p r o x i m i t y warning d e v i c e s on air
carrier aircraft.
3.
The F A A continue to e m p h a s i z e the i m p o r t a n c e of
the p r o v i s i o n s of Part 121.445 i n i t s s u r v e i l l a n c e and
i n s p e c t i o n of flight o p e r a t i o n s under Part 121. Such
e m p h a s i s is needed to a s s u r e t h a t t h e s e o p e r a t o r s a r e (1)
u s i n g the b e s t m e a n s a v a i l a b l e to enable p i l o t s to qualify
u n d e r 121.445, and ( 2 ) r e q u i r i n g p i l o t s to show t h a t they
h a v e a c q u i r e d the r e q u i s i t e knowledge p r i o r to completion
of a flight r e l e a s e .
- 2 -
1.
INVESTIGATION
---
1. 1 H i s t o r y of the F l i g h t
S o u t h e r n A i r w a y s C h a r t e r F l i g h t 932 (SOU 932) 1 / w a s s c h e d u l e d
as a f e r r y f l i g h t f r o m A t l a n t a , G e o r g i a , t o Kinston, N o r t h C a r o l i n a , t o
r e t u r n m e m b e r s of t h e M a r s h a l l U n i v e r s i t y football t e a m , the coaching
staff, and o t h e r p a s s e n g e r s t o Huntington, W e s t V i r g i n i a , f r o m Kinston.
The flight w a s t h e n s c h e d u l e d t o continue t o Hopkinsville, Kentucky, and
A l e x a n d r i a and Baton Rouge, L o u i s i a n a . The c r e w c o n s i s t e d of a c a p t a i n ,
a first o f f i c e r , and two s t e w a r d e s s e s , In addition, a n o p e r a t i o n s e m p l o y e e
w a s a s s i g n e d as a c h a r t e r c o o r d i n a t o r .
The f l i g h t c r e w w a s given a s t a n d a r d b r i e f i n g b y c o m p a n y d i s p a t c h
and a c h a r t e r k i t of a p p r o p r i a t e documents, including: (1) J e p p e s e n Manuals
f o r high and low altitude a i r w a y s , a n d a p p r o a c h c h a r t s f o r all m a j o r c i v i l
and m i l i t a r y a i r p o r t s i n the U. S. ; ( 2 ) the c u r r e n t A i r m a n ' s I n f o r m a t i o n
Manual, P a r t s I, 11, and 111; ( 3 ) a c o m p l e t e s e t of S e c t i o n a l A e r o n a u t i c a l
C h a r t s ; and ( 4 ) all the n e c e s s a r y flight f o r m s f o r c a r g o loading, w e i g h t
and b a l a n c e , flight planning, d a i l y i n s p e c t i o n and m a i n t e n a n c e , and c r e d i t
c a r d s . In a d d i t i o q a copy of the S o u t h e r n DC-9 off-line a i r p o r t r e s t r i c t i o n s
w a s c a r r i e d by the c h a r t e r c o o r d i n a t o r , and a n o t h e r copy w a s k e p t on e a c h
a i r c r a f t . The s t e w a r d e s s e s and c h a r t e r c o o r d i n a t o r b o a r d e d the a i r c r a f t
w i t h the f l i g h t c r e w at A t l a n t a and the a i r c r a f t w a s f e r r i e d t o Kinston.
The flight d e p a r t e d A t l a n t a at 1548 2 / and a r r i v e d at K i n s t o n at 1642.
The a i r c r a f t w a s r e f u e l e d , b u t no m a i n t e n a n c e w a s r e q u e s t e d o r p e r f o r m e d .
Seventy p a s s e n g e r s b o a r d e d the a i r c r a f t and the flight t a x i e d f r o m the r a m p
at 1828 w i t h a t o t a l of 75 p e r s o n s a b o a r d .
The c a p t a i n f i l e d a n I n s t r u m e n t F l i g h t R u l e s ( I F R ) flight p l a n t o
Huntington, v i a d i r e c t R a l e i g h - D u r h a m , N o r t h C a r o l i n a , d i r e c t Pulaski,
V i r g i n i a , d i r e c t Huntington, a t F l i g h t L e v e l 260 ( F L 260). The t r u e airs p e e d w a s 473 knots and the e s t i m a t e d t i m e e n r o u t e w a s 52 m i n u t e s . The
flight d e p a r t e d K i n s t o n at 1838 and p r o c e e d e d in a c c o r d a n c e w i t h t h e flight
plan. Subsequent air t r a f f i c c o n t r o l t r a n s f e r s w e r e a c c o m p l i s h e d and, at
1923, SOU 932 e s t a b l i s h e d c o n t a c t with Huntington A p p r o a c h C o n t r o l by a d v i s -
1 / The p r i m a r y d i f f e r e n c e b e t w e e n this c h a r t e r f l i g h t a n d a r e g u l a r l y
s c h e d u l e d flight conducted u n d e r S o u t h e r n A i r w a y s ' o p e r a t i n g c e r t i f i c a t e is
the a p p l i c a b l e landing m i n i m a . The F e d e r a l Aviation Regulations i m p o s e
h i g h e r landing m i n i m a o n the pilot of a c h a r t e r flight, u n l e s s he is qualified
at the a i r p o r t a n d l o w e r m i n i m a have b e e n e s t a b l i s h e d f o r the a i r p o r t in the
air c a r r i e r ' s o p e r a t i o n s s p e c i f i c a t i o n s . In t h i s i n s t a n c e the n o r m a l m i n i m a
f o r Runway 11 w e r e i n c r e a s e d f r o m 1 , 2 4 0 f e e t and 1 / 2 - m i l e t o 1 , 2 4 0 f e e t
and 1 m i l e .
2 / A l l t i m e s h e r e i n a r e e a s t e r n s t a n d a r d , b a s e d o n the 24-hour clock.
- 3 -
..
ing, ' I .
w e ' r e descending to five thousand. I ' 3 / The c o n t r o l l e r
c l e a r e d t h e m f o r a l o c a l i z e r a p p r o a c h to R u n w a y 1 1 and added,
the s u r f a c e winds are favoring runway twenty-nine, three five
'I.
. ' I
The c r e w
z e r o d e g r e e s at six, a l t i m e t e r two n i n e r six seven.
acknowledged t h i s information and then the c o n t r o l l e r advised,
'I.
the Huntington w e a t h e r t h r e e hundred s c a t t e r e d , m e a s u r e d
ceiling five hundred, v a r i a b l e b r o k e n , one thousand one hundred o v e r c a s t , visibility five, light r a i n , fog, s m o k e , ceiling r a g g e d v a r i a b l e
f o u r to s i x hundred.
..
..
..
At a p p r o x i m a t e l y 1933, the captain s a i d that he would f l y at 130
knots, and the f i r s t o f f i c e r responded that he w a s checking the t i m e , and
the a p p r o a c h should take 2 m i n u t e s . At 1934, the c r e w r e p o r t e d p a s s i n g
the o u t e r m a r k e r inbound, and they w e r e c l e a r e d to land. T h e wind w a s
then r e p o r t e d as 340°, 7 knots. Following a d i s c u s s i o n of the a p p r o a c h
lighting during which the c r e w r e q u e s t e d " s t e p t h r e e , I ' the tower c o n t r o l l e r
s t a t e d , "Roger, t h a t ' s w h e r e they a r e , with the r a b b i t (sequence flasher).
Advise when you want t h e m cut. I ' The c r e w ' s r e s p o n s e , "Very good, I ' w a s
the l a s t t r a n s m i s s i o n r e c e i v e d . At a p p r o x i m a t e l y 1936, tower p e r s o n n e l
o b s e r v e d a r e d glow w e s t of the a i r p o r t , When no r e s p o n s e to subsequent
r a d i o c a l l s w a s r e c e i v e d , the tower c o n t r o l l e r initiated the e m e r g e n c y
procedures.
W i t n e s s e s in the vicinity of the Runway 11 l o c a l i z e r c o u r s e g e n e r a l l y
a g r e e d that the a i r c r a f t w a s low, but o t h e r w i s e a p p e a r e d normal. The
w e a t h e r w a s d e s c r i b e d as v a r y i n g between mist and light r a i n with low
clouds. Some w i t n e s s e s a l s o indicated t h a t visibility w a s r e s t r i c t e d due
t o fog. However, one w i t n e s s who w a s a p p r o x i m a t e l y two-thirds of a m i l e
w e s t of the initial i m p a c t site o b s e r v e d the a i r c r a f t p a s s approximately
300 feet above h i m and d i s a p p e a r f r o m view beyond the hill. He saw the
h i l l outlined in "good detail" by a glow f r o m beyond the hill, and h e a r d a n
i n c r e a s e i n j e t engine noise p r i o r to the c r a s h . Another w i t n e s s , who w a s
a p p r o x i m a t e l y 700 f e e t e a s t of the initial i m p a c t , s t a t e d that the aircraft
r o l l e d to the right, a l m o s t i n v e r t e d , and c r a s h e d i n a steep,nosedown angle.
The tower c o n t r o l l e r s t a t e d t h a t he maintained a continuous w a t c h f o r
SOU 932 once they r e p o r t e d p a s s i n g the o u t e r marker. Although he did not
s e e the a i r c r a f t , he did o b s e r v e the fire and explosion f r o m the c r a s h . He
did not recall any d i f f e r e n c e s between the r e p o r t e d and a c t u a l w e a t h e r p r i o r
t o the accident,
-3 /
A t r a n s c r i p t of p e r t i n e n t cockpit c o n v e r s a t i o n is included in Appendix D.
- 4 -
T h e last flight t o o p e r a t e into Huntington p r i o r t o SOU 932 landed on
Runway 1 1 at 1848 and d e p a r t e d at 1907. T h e c a p t a i n of t h a t flight s t a t e d
t h a t the w e a t h e r w a s e s s e n t i a l l y as r e p o r t e d t o him, 300 feet s c a t t e r e d ,
500 f e e t v a r i a b l e b r o k e n , T h e y b r o k e out of the clouds at m i n i m u m s , w e s t
of the r e f i n e r y ( l o c a t e d a p p r o x i m a t e l y 2 miles w e s t of the a i r p o r t ) . The
f o r w a r d v i s i b i l i t y w a s good, and the runway w a s i n s i g h t f r o m t h i s point
until they landed, although they did e n c o u n t e r s o m e widely s c a t t e r e d s c u d
clouds.
The accident o c c u r r e d during h o u r s of d a r k n e s s at 38O 22' 27"
latitude and 82O 34' 42" W. longitude,
N.
1. 2 I n j u r i e s t o P e r s o n s
Iniur ie s
Crew
P a s s e nrre r s
Others
Fatal
Nonfatal
None
4
71
0
0
0
0
0
0
1. 3 Damage t o A i r c r a f t
The a i r e r a f t w a s destroyec b y i m p a c t and grounc f i r e .
1.4 Other Damage
The aircraft d e s t r o y e d m a n y trees on a hill a p p r o x i m a t e l y 1 , 3 0 0 f e e t
w e s t of the m a i n w r e c k a g e site,
1. 5 C r e w Information
The c r e w w a s qualified f o r the flight,
1.6 A i r c r a f t Information
(See Appendix B f o r d e t a i l s . )
1
The a i r c r a f t w a s c e r t i f i c a t e d and m a i n t a i n e d i n a c c o r d a n c e with
existing r e g u l a t i o n s , It w a s fueled with Jet A-1 k e r o s e n e . (See Appendix
C f o r details. )
1 . 7 Meteorological Information
A t the time of the accident, a l o w - p r e s s u r e area w a s c e n t e r e d n e a r
s o u t h w e s t e r n W e s t Virginia. A f r o n t a l s y s t e m extended southward f r o m
- 5 -
that a r e a and the a c c i d e n t s i t e w a s included i n a n extensive zone of low
c l o u d i n e s s and p r e c i p i t a t i o n a s s o c i a t e d with t h e s e synoptic f e a t u r e s ,
The a v i a t i o n area forecast f o r W e s t V i r g i n i a , i s s u e d by the National
W e a t h e r S e r v i c e (NWS) office at Suitland, Maryland, valid f o r a 12-hour
p e r i o d , beginning at 1400, w a s , in p a r t , as follows:
Low p r e s s u r e developing o v e r the s o u t h e a s t e r n s t a t e s
and c e n t e r e d o v e r n o r t h e a s t e r n A l a b a m a , expected to
move n o r t h e a s t w a r d a t 15 to 20 knots w i l l lie o v e r
w e s t e r n N o r t h C a r o l i n a s o u t h w e s t e r n V i r g i n i a by 0200.
F l i g h t p r e c a u t i o n re c o m m e nded throughout f o r e c a s t a r e a
b e c a u s e of lowering ceilings and v i s i b i l i t i e s and a l s o
b e c a u s e of o c c a s i o n a l turbulence and p o s s i b l e icing.
. .
,
g e n e r a l l y ceiling 1, 000 to 2 , 000
O v e r W e s t Virginia
f e e t o v e r c a s t , 3 to 6 m i l e s , h a z e , o c c a s i o n a l ceiling 300
to 500 f e e t o v e r c a s t , 1 t o 2 m i l e s , fog, s c a t t e r e d light
r a i n , Conditions lowering m o r e e x t e n s i v e l y a f t e r 1700,
becoming m o r e f r e q u e n t l y ceiling 500 t o 1 , 0 0 0 f e e t o v e r c a s t , 1 - 1 / 2 t o 3 m i l e s , light r a i n , fog, and occasional
ceiling 3 0 0 t o 500 f e e t o v e r c a s t , 3/4 t o 1 - 1 / 2 m i l e s ,
light r a i n , fog, with light r a i n t o o c c a s i o n a l m o d e r a t e
rain.
...
F r e e z i n g l e v e l 6 , 0 0 0 t o 8 , 0 0 0 f e e t o v e r mountains
o c c a s i o n a l m o d e r a t e icing i n clouds l i k e l y above the
f r e e z i n g level.
...
The t e r m i n a l f o r e c a s t f o r Huntington, i s s u e d a t 1145, and valid f o r
a 12-hour p e r i o d beginning at 1200 w a s in p a r t as follows:
1200-2100, ceiling 500 f e e t o v e r c a s t , 2 m i l e s , light r a i n ,
fog, s m o k e , wind 030°, 12 knots, v a r i a b l e to ceiling 300
f e e t o v e r c a s t , 1 m i l e , light r a i n , fog.
1 ,,+, 1
The next routine t e r m i n a l f o r e c a s t w a s i s s u e d a t 1745, valid f o r a
~ 2 - h 0 p r , ~ ~ beginning
~$bd
at 1800 and was in p a r t as follows:
1);
- 6 -
1800-2300, 300 f e e t s c a t t e r e d , ceiling 500 f e e t broken,
1 , 0 0 0 f e e t o v e r c a s t , 1 - 1 / 2 m i l e s , light r a i n , fog,
s c a t t e r e d clouds v a r i a b l e t o broken.
The official s u r f a c e w e a t h e r o b s e r v a t i o n s f o r Huntington b r a c k e t i n g
t h e t i m e of the a c c i d e n t w e r e as follows:
1855, 300 f e e t s c a t t e r e d , m e a s u r e d 500 f e e t v a r i a b l e
b r o k e n , 1, 100 f e e t o v e r c a s t , 5 m i l e s , light r a i n , fog,
s m o k e , t e m p e r a t u r e 49O, dewpoint 47O, wind 360°,
4 knots, 2 9 - 67, ceiling r a g g e d and v a r i a b l e 400 t o
600 f e e t .
1945, 300 f e e t s c a t t e r e d , e s t i m a t e d 500 f e e t b r o k e n ,
1 , 0 0 0 f e e t o v e r c a s t , 5 m i l e s , light r a i n , fog, s m o k e ,
t e m p e r a t u r e 49O, dewpoint 47O, wind 210°, 4 knots,
29.67, ceiling r a g g e d , a i r c r a f t accident.
1956, r e c o r d s p e c i a l , p a r t i a l o b s c u r a t i o n , e s t i m a t e d 500
o v e r c a s t , 3 / 4 - m i l e v e r y light r a i n , fog, s m o k e , t e m p e r a t u r e
49O, dewpoint 470, wind 290°, 5 k n o t s , 29.67, fog o b s c u r i n g
5 / 1 0 of the sky, ceiling r a g g e d , i n t e r m i t t e n t v e r y light r a i n .
The National W e a t h e r S e r v i c e s p e c i a l i s t who m a d e the o b s e r v a t i o n s
I thought the v i s i b i l i t y w a s r e m a r k a b l y good when I
t e s t i f i e d that ' I .
took m y l o c a l ( t h e 1945 o b s e r v a t i o n ) , but about 10 o r 15 minutes a f t e r
that the fog f o r m e d v e r y rapidly, and that's when the visibility c a m e
it w a s r i g h t o v e r the field. It j u s t s e e m e d like it f o r m e d v e r y
down. ,
r a p i d l y and it j u s t a c t u a l l y s a n k r i g h t o v e r the whole field. I '
..
.
The Huntington 1900 radiosonde a s c e n t showed s a t u r a t e d o r v i r t u a l l y
s a t u r a t e d conditions with s t a b l e air f r o m about 2,000 t o 5 , 0 0 0 f e e t and
o t h e r w i s e a m o i s t a d i a b a t i c l a p s e r a t e , The f r e e z i n g l e v e l w a s at 7, 500
f e e t , The u p p e r wind o b s e r v a t i o n a s s o c i a t e d with this a s c e n t w a s in p a r t
as follows:
Height
( f e e t m. s. 1. )
Surface
2,000
3,000
D i r e c t ion
(Otrue)
36 0
075
130
- 7 -
Ve l o c it y
(knots)
7
12
18
A study of p r e s s u r e p a t t e r n s i n the W e s t V i r g i n i a a r e a , at the
t i m e of t h e a c c i d e n t , w a s conducted f o r the Safety B o a r d by the
National W e a t h e r S e r v i c e following the i n i t i a l public h e a r i n g . The study
showed t h a t the dominant l o w - p r e s s u r e a r e a w a s elongated t o w a r d the
n o r t h e a s t with s u r f a c e p r e s s u r e s dropping a t a n a v e r a g e r a t e of 0. 013
i n c h . of m e r c u r y / h o u r . T h i s would c o r r e s p o n d t o a n indicated altitude
i n c r e a s e of 13 f e e t / h o u r . The l o w - p r e s s u r e a r e a m o v e d s t e a d i l y n o r t h e a s t w a r d w i t h l i t t l e change in intensity. Although t h e r e w a s a n e x t e n s i v e
a r e a of light r a i n , no s h o w e r y p r e c i p i t a t i o n ( p o s s i b l y indicative of m o r e
r a p i d p r e s s u r e v a r i a t i o n ) w a s r e p o r t e d within 250 m i l e s of Huntington.
1. 8 A i d s to Navigation
The T r i - S t a t e A i r p o r t w a s equipped w i t h a n ILS l o c a l i z e r , but no glide
slope. The l o c a l i z e r p r o v i d e d a n o n p r e c i s i o n a p p r o a c h t o Runway 11. The
c r e w ' s J e p p e s e n A p p r o a c h C h a r t depicting this p r o c e d u r e w a s d a t e d D e c e m b e r 27, 1968; h o w e v e r , t h e c u r r e n t a p p r o a c h c h a r t at the t i m e of the
a c c i d e n t w a s d a t e d N o v e m b e r 6 , 1970. (See A t t a c h m e n t 2 , ) The r e v i s e d
a p p r o a c h c h a r t w a s i n c o r p o r a t e d in S o u t h e r n ' s c h a r t e r k i t s on N o v e m b e r 13,
1970, by the chief pilot, Two k i t s w e r e not a v a i l a b l e on that date b e c a u s e
t h e y w e r e in u s e a t the t i m e , including the c h a r t e r k i t on N97S which had
d e p a r t e d a t a p p r o x i m a t e l y 0830 on the d a y the r e v i s i o n s w e r e i n s e r t e d . The
b a s i c d i f f e r e n c e s in the two a p p r o a c h c h a r t s w e r e : ( 1 ) a n i n c r e a s e in
the M i n i m u m S e c t o r Altitude 4 / f r o m 2, 500 f e e t t o 2 , 6 0 0 f e e t m. s. 1. , f o r
the s e c t o r w e s t of the airport(180° c l o c k w i s e t h r o u g h 360' i n c l u s i v e ) ; and
( 2 ) the addition of holding i n s t r u c t i o n s to the m i s s e d - a p p r o a c h p r o c e d u r e
text.
The L o c a l i z e r - R u n w a y 11 a p p r o a c h r e q u i r e d a p r o c e d u r e t u r n s o u t h
of the 114O l o c a l i z e r c o u r s e within 10 m i l e s of the o u t e r m a r k e r , at
2 , 6 0 0 f e e t m. s . 1, The o u t e r m a r k e r m i n i m u m c r o s s i n g altitude w a s
2 , 2 0 0 f e e t m. s. 1. , and f u r t h e r d e s c e n t w a s t h e n a u t h o r i z e d t o the
M i n i m u m D e s c e n t Altitude (MDA) 5 / of 1 , 2 4 0 f e e t m. s. 1. The o u t e r
-
4 / M i n i m u m S e c t o r Altitude
p r o v i d e s 1, 000-foot o b s t a c l e c l e a r a n c e
within a 25-mile r a d i u s of a navigation f a c i l i t y ( e x c e p t l o c a l i z e r s without
a n o n d i r e c t i o n a l b e a c o n ) , A s e c t o r m a y not be l e s s t h a n 90° in s p r e a d ,
and the o b s t a c l e c l e a r a n c e m u s t a l s o apply i n a d j a c e n t a r e a s within 4
m i l e s of the s e c t o r boundary, A l l a l t i t u d e s a r e m e a n s e a l e v e l (m. s. 1. )
u n l e s s o t h e r w i s e indicated.
5 / M i n i m u m D e s c e n t Altitude is the l o w e s t altitude t o w h i c h d e s c e n t shall
be a u t h o r i z e d in p r o c e d u r e s not using a glide s l o p e , A i r c r a f t a r e not
a u t h o r i z e d t o d e s c e n d below the MDA until the runway e n v i r o n m e n t ( r u n w a y
t h r e s h o l d , o r a p p r o v e d lighting a i d s or o t h e r m a r k i n g s identifiable with
the runway) is i n s i g h t and the a i r c r a f t is i n a p o s i t i o n t o d e s c e n d f o r a
n o r m a l landing,
- 8 -
m a r k e r and m i d d l e m a r k e r w e r e l o c a t e d 4.6 and 0 . 6 m i l e s , r e s p e c t i v e l y ,
f r o m the runway t h r e s h o l d , The l o c a l i z e r w a s offset a p p r o x i m a t e l y 0. 7 O
to the s o u t h of the runway c e n t e r l i n e . The offset w a s a c c o m p l i s h e d to place
the antenna on s t a b l e ground w h e r e the e l e c t r o n i c s i g n a l would r e m a i n
within t o l e r a n c e s , A flight check of the f a c i l i t i e s w a s a c c o m p l i s h e d by
the F e d e r a l Aviation A d m i n i s t r a t i o n (FAA) on November 15, 1970, and
all w e r e found s a t i s f a c t o r y ,
An i n s t r u m e n t landing s y s t e m w a s scheduled f o r installation and
c o m m i s s i o n i n g a t the T r i - S t a t e A i r p o r t in June 1958. The l o c a l i z e r ,
m i d d l e m a r k e r , and o u t e r m a r k e r i n s t a l l a t i o n s w e r e c o m p l e t e d a t that
t i m e , but t h e r e w a s insufficient t e r r a i n to provide adequate reflecting
s u r f a c e f o r the glide-slope a n t e n n a , within the existing c r i t e r i a . T h r e e
applications for runway e x t e n s i o n , which would a l s o provide suitable
t e r r a i n f o r the glide-slope antenna, w e r e s u b m i t t e d to the F A A in
F i s c a l Y e a r s 1967, 1970 and 1971, The 1967 and 1970 r e q u e s t s w e r e
not a p p r o v e d b e c a u s e the n e c e s s a r y "matching funds" f r o m the s p o n s o r i n g
agency w e r e not a v a i l a b l e , and consequently the F e d e r a l funds w e r e not
c o m m i t t e d . The 1971 r e q u e s t w a s s t i l l u n d e r c o n s i d e r a t i o n a t the t i m e
of the accident.
Subsequent to the a c c i d e n t , c o n c u r r e n t negotiations involving the
FAA, We s t V i r g i n i a State Ae r onautic s C o m m i s s ion, W ilcox E le c t r ic
Company, I n c . , and the T r i - S t a t e A i r p o r t A u t h o r i t y , r e s u l t e d i n the
installation of a n o n s t a n d a r d glide slope f o r Runway 11, paid f o r by
F e d e r a l funds only. P r i o r bo installation, the FAA e s t i m a t e d that t h e r e
was a 50 p e r c e n t probability of s u c c e s s with the glide slope. A Wilcox
M a r k I, S e r i e s 8020 t r a n s m i t t e r w a s p l a c e d 1 , 2 1 1 f e e t s o u t h of the runway
c e n t e r l i n e and 960 f e e t w e s t of the Runway 29 t h r e s h o l d , The elevation of
the s i t e w a s 805. 2 f e e t m. s. 1. and the a n t e n n a w a s r o t a t e d 13. 5 O to align
with the m i d d l e m a r k e r . T h i s offset w a s r e q u i r e d to place the s i t e o n
suitable t e r r a i n , and r e s u l t e d in a n unuseable s i g n a l below 1, 075 feet
m. s. 1. Consequently, t h e r e w a s no r e d u c t i o n i n the m i n i m u m altitude
a u t h o r i z e d f o r the i n s t r u m e n t a p p r o a c h . However, the s i g n a l g e n e r a t i n g
capability of the facility to date h a s b e e n a s r e l i a b l e a s s t a n d a r d s y s t e m s ,
1. 9 C o m m u n i c a t i o n s
T h e r e w e r e no known difficulties with radio c o m m u n i c a t i o n s ,
1. 10 A e r o d r o m e and Ground F a c i l i t i e s
The T r i - S t a t e A i r p o r t w a s l o c a t e d on a hilltop a p p r o x i m a t e l y 2. 5
m i l e s southwest of Huntington, W e s t Virginia, a t a n e l e v a t i o n of 828 feet
- 9 -
m. s. 1. The only runway w a s Runway 11-29. It w a s 5 , 2 8 1 f e e t long
and 150 f e e t wide, and w a s of c o n c r e t e construction. Runway 11 w a s
equipped with high-intensity runway l i g h t s , a p p r o a c h l i g h t s , and
sequence f l a s h e r s . All lighting w a s operating s a t i s f a c t o r i l y , T h e r e
w a s no v i s u a l a p p r o a c h slope i n d i c a t o r (VASI) s y s t e m installed.
T h e r e w a s v e r y little l e v e l land extending beyond e i t h e r end of the
runway; however, t h e r e w e r e o t h e r hills of similar s i z e and elevation
surrounding the a i r p o r t . The highest o b s t a c l e in the a r e a underlying
the l o c a l i z e r c o u r s e w a s a t r e e 6 , 7 0 0 f e e t e a s t of the o u t e r m a r k e r , a t
a n elevation of 990 f e e t m. s. 1. By c o n t r a s t , the Ohio R i v e r and Big
Sandy R i v e r p a s s e d within a few m i l e s of the a i r p o r t a t elevations of
a p p r o x i m a t e l y 500 f e e t m. s. 1. in the north, w e s t , and south q u a d r a n t s .
An a r e a of b r i g h t lights s u r r o u n d i n g a r e f i n e r y w a s l o c a t e d on the w e s t
bank of the Big Sandy R i v e r j u s t south of the l o c a l i z e r c o u r s e , about
2 m i l e s w e s t of t h e runway threshold.
1. 11 Flight R e c o r d e r s
The a i r c r a f t w a s equipped with a Sundstrand flight data r e c o r d e r ,
Model F-542, S / N 1047. The r e c o r d e r unit had been exposed to e x t r e m e
h e a t in the f i r e a f t e r i m p a c t , but the r e c o r d i n g m e d i u m magazine w a s
e a s i l y r e m o v e d and the r e c o r d e d foil s u r f a c e w a s v i r t u a l l y undamaged.
A r e a d o u t of the last 10 m i n u t e s of n o r m a l l y r e c o r d e d t r a c e s w a s
p r e p a r e d . The altitude t r a c e w a s a d j u s t e d f o r a n a l t i m e t e r s e t t i n g of
29. 67 t o indicate m. s. 1. a l t i t u d e s , but no o t h e r c o r r e c t i o n s w e r e m a d e
to the data. Additional c h e c k s of the altitude t r a c e w e r e m a d e as follows:
Location
Atlanta A i r p o r t
C r u i s e FL 2 9 0
Stallings F i e l d
(Kinston)
Cruise F L 260
Altimeter
Setting
Re c o r d e d
Difference
29. 71
29.92
29.90
29.92
Tolerance
-
18 f e e t
t 200
-
+
+
-
100 f e e t
450
t 88
t 235
-
+
+
100
400
The l a s t 0. 036-inch of foil t r a v e l contained sudden deviations in all
r e c o r d e d t r a c e s . T h i s a b e r r a n t a r e a , equivalent t o 21.6 s e c o n d s of
e l a p s e d t i m e during n o r m a l operation, included a 0. 009-inch s e g m e n t
without the r e c o r d i n g of any p a r a m e t e r t r a c e . With the a s s i s t a n c e of
the m a n u f a c t u r e r , v a r i o u s t e s t s w e r e conducted to duplicate the indications on the flight data r e c o r d e r foil. Mechanical and e l e c t r i c a l c h e c k s ,
g-loading on all t h r e e axes with i n d i s c r i m i n a t e i n t e r r u p t i o n s of e l e c t r i c a l
- 10
-
p o w e r , and a t t e m p t s m e c h a n i c a l l y to impede o r a c c e l e r a t e f o i l t r a v e l
all failed to p r o v i d e a s a t i s f a c t o r y e x p l a n a t i o n f o r the a b e r r a t i o n s . It
w a s d e t e r m i n e d that the 0 , 0 0 9 - i n c h skip w a s c a u s e d by a s h o c k of
unknown magnitude o r o r i g i n , A l s o , though s o m e s c r i b e m a r k s d u r i n g
the 0. 036-inch t r a v e l w e r e n o r m a l i n a p p e a r a n c e , t h e r e w a s no c o r r e l a tion between the r e c o r d e d p a r a m e t e r s , e x c e p t that the downward e x c u r s i o n s a p p e a r e d to have b e e n c a u s e d by a heavy s h o c k in e x c e s s of
30g's.
The flight data r e c o r d e r s t a t i c p r e s s u r e s o u r c e is the a i r c r a f t
a l t e r n a t e s t a t i c s y s t e m , T h i s s y s t e m i s c o m p l e t e l y s e p a r a t e f r o m the
c a p t a i n ' s and f i r s t o f f i c e r ' s n o r m a l s t a t i c p r e s s u r e s y s t e m s , e x c e p t
that it is available a s a backup s o u r c e f o r t h e i r i n s t r u m e n t s , if s e l e c t e d
by them. The a l t e r n a t e s t a t i c p o r t s a r e l o c a t e d on e i t h e r side of the
a i r c r a f t c e n t e r l i n e a p p r o x i m a t e l y 10 f e e t f o r w a r d , and slightly below,
the n o r m a l s t a t i c p o r t p a n e l s ,
The a i r c r a f t w a s a l s o equipped with a Collins cockpit voice r e c o r d e r
( C V R ) , Model 642-C-1, S / N 508. The unit had s u s t a i n e d c o n s i d e r a b l e
i m p a c t d a m a g e to the e l e c t r o n i c s package, but t h e r e w a s no d a m a g e
within the s t a i n l e s s s t e e l c a s e of the tape m a g a z i n e , T h e r e w a s c o n s i d e r a b l
"wow and f l u t t e r " on the t a p e , indicating a m e c h a n i c a l d i s t r e s s condition
within the r e c o r d e r . T h e r e w a s a l s o m a r k e d i n t e r f e r e n c e f r o m background
n o i s e and the cockpit s p e a k e r s . A p a r t i a l t r a n s c r i p t of the r e a d o u t is
a t t a c h e d a s Appendix D.
1. 12 Wreckage
The a i r c r a f t initially s t r u c k t r e e s on a h i l l 5 , 5 4 3 f e e t w e s t of the
runway t h r e s h o l d , and cut a swath 9 5 f e e t wide and 279 f e e t long through
the t r e e s on a b e a r i n g of l l O o , 122 f e e t right of the Runway 11 c e n t e r l i n e
extended. S e v e r a l s e c t i o n s of wing l e a d i n g e d g e , one t r a i l i n g edge flap
moveable vane, and a flap t r a c k , all f r o m the r i g h t wing, and t h r e e l a r g e
s e c t i o n s of r a d o m e w e r e l o c a t e d n e a r the s w a t h cut.
The m a i n w r e c k a g e s i t e w a s l o c a t e d 4 , 2 1 9 f e e t f r o m the t h r e s h o l d of
Runway 11, and a p p r o x i m a t e l y 225 f e e t south of the m i d d l e m a r k e r , The
a i r c r a f t cut a s w a t h 39O below the h o r i z o n t a l through the t r e e s a t the
w r e c k a g e s i t e and c a m e to r e s t i n a n i n v e r t e d attitude.
The ground e l e v a t i o n a t the initial t r e e i m p a c t w a s 860 f e e t m. s . l.,
and the e l e v a t i o n a t the b r e a k in the t r e e a t t h i s location w a s 916 f e e t 2
-
11 -
inches m. s. 1. The h i g h e s t ground elevation a d j a c e n t to the swath cut
w a s 894. 5 f e e t m. s. 1. T r e e heights a t t h i s point m e a s u r e d 50 feet,
which c o r r e s p o n d e d to a t r e e t o p elevation of 944.5 f e e t m. s. 1. The
ground e l e v a t i o n n e a r the c r e s t of the h i l l in the c e n t e r of the swath
cut w a s 880 f e e t m, s. 1. The b r e a k in a p o p l a r t r e e a t this point w a s
42 f e e t above the ground (922 f e e t m. s. 1. ) ' However, the U. S . D e p a r t m e n t of A g r i c u l t u r e F o r e s t S e r v i c e e s t i m a t e d that the t r e e w a s 71 f e e t
( 4 1 foot) t a l l b e f o r e b r e a k a g e , b a s e d on a s t u d y of o t h e r t r e e s in the
a r e a , The MDA w a s a p p r o x i m a t e l y 2 9 0 f e e t above the e s t i m a t e d
maximum elevation of the t r e e top. The s w a t h cut between the initial
t r e e i m p a c t and the b r e a k in the poplar t r e e w a s 4 2 O , m e a s u r e d f r o m
the horizontal, The d i s t a n c e between t h e s e two t r e e s w a s a p p r o x i m a t e l y
152 feet.
-
Most of the f u s e l a g e w a s m e l t e d o r r e d u c e d to a p o w d e r - l i k e
s u b s t a n c e ; h o w e v e r , s e v e r a l l a r g e p i e c e s w e r e s c a t t e r e d throughout
the burned a r e a . E x a m i n a t i o n of the v a r i o u s components indicated that
the landing g e a r and flaps w e r e fully extended a t i m p a c t , The h o r i z o n t a l
s t a b i l i z e r setting w a s 5. 7 5 units noseup, which w a s in the n o r m a l range
f o r the weight, and s p e e d , i n the a p p r o a c h configuration.
1. 1 3 F i r e
A s e v e r e ground f i r e at the m a i n w r e c k a g e s i t e followed i m p a c t .
Firefighting activity at the c r a s h s i t e w a s l i m i t e d to containing b r u s h
f i r e s in the a r e a . T h e r e w a s no evidence of in-flight f i r e .
1. 14 S u r v i v a l A s p e c t s
T h i s w a s a nonsurvivable accident.
1 . 1 5 T e s t s and R e s e a r c h
In reviewing the c i r c u m s t a n c e s of t h i s accident, the Safety Board again
took notice of t e s t s conducted by the Douglas A i r c r a f t Company (DACO) i n
May 1967. The t e s t s w e r e designed to study the effect of p o s s i b l e w a t e r
ingestion in the s t a t i c p o r t s of the a i r c r a f t . S e v e r a l DACO field s e r v i c e
r e p o r t s had indicated that during final d e s c e n t on ILS a p p r o a c h e s , w i t h
full flaps and landing g e a r extended, the a l t i m e t e r w a s a l t e r n a t e l y
At e a c h m o m e n t a r y pause and subsequent
"pausing" and then ''jumping.
jump, the i n s t a n t a n e o u s v e r t i c a l s p e e d indicator tended t o w a r d z e r o .
Most of the lIjumpsllw e r e between 40 and 60 f e e t , but s e v e r a l w e r e 80
t o 100 f e e t i n magnitude,
-
12
-
The i n i t i a l t e s t s w e r e conducted in a n altitude c h a m b e r . It w a s
found that e a c h p o r t of a s t a t i c plate e n t r a i n e d w a t e r by c a p i l l a r y
a c t i o n , and p r e s s u r e d i f f e r e n t i a l s e q u i v a l e n t t o about 35 f e e t i n
altitude, a t s e a l e v e l , w e r e r e q u i r e d to e x p e l the w a t e r , A s e r i e s
of r u n s v e r i f i e d t h a t any i n c r e a s e in the d i a m e t e r of the o r i f i c e
d e c r e a s e d the magnitude of the " j u m p s , ' I V a r i a t i o n s in the r a t e of
d e s c e n t affected the r a t e of 'ljumps, ' I b u t not the magnitude.
Flow visualization t e s t s w e r e t h e n conducted in the wind tunnel
w i t h 1 / 5 0 - s c a l e DC-9-10 and DC-8-55 m o d e l s t o identify any m e c h a n i s m
that m i g h t t e n d to c o n c e n t r a t e w a t e r i n the vicinity of the s t a t i c p o r t s .
The t e s t i n g c o v e r e d both no-flap and 50°-flap c o n f i g u r a t i o n s a t a n g l e s
The o b s e r v e d f b w w a s o r d e r l y , and
of a t t a c k ranging f r o m -8O to $8'.
the only deviation w a s a r o u n d a high velocity r e g i o n on the nose of the
DC-9. T h i s w a s l a t e r found to be due to m o d e l a s y m m e t r y .
A c t u a l f l i g h t t e s t s w e r e conducted in light-to-heavy r a i n w i t h a
DC-9-30 in the following flight conditions: d e s c e n t i n the landing conf i g u r a t i o n f o r both the DC-9-10 6 / and DC-9-30, and d e s c e n t i n the c l e a n
c o n f i g u r a t i o n that w a s r e p r e s e n t a t i v e of both a i r c r a f t . Nine s i m u l a t e d
ILS a p p r o a c h e s w e r e flown in the DC-9-30 landing configuration. 7 / Both
the n o r m a l and a l t e r n a t e s t a t i c s y s t e m s w e r e m o n i t o r e d throughout, and
no i n s t a n c e s of s t i c k y a l t i m e t e r o p e r a t i o n w e r e o b s e r v e d . Additionally,
'
five typical d e s c e n t s w e r e m a d e in the c l e a n configuration, a t 2, 500 t o
3,000 f e e t / m i n u t e , t h r o u g h light to s p o r a d i c a l l y heavy r a i n . No evidence
of s t i c k y a l t i m e t e r o p e r a t i o n w a s d e t e c t e d on any s y s t e m ,
A t the r e q u e s t of the Safety B o a r d and the FAA, the National A e r o n a u t i c s and Space A d m i n i s t r a t i o n h a s u n d e r t a k e n a long t e r m Static P r e s s u r e .
M e a s u r e m e n t s P r o j e c t at the Lewis R e s e a r c h C e n t e r . T h i s e x p l o r a t o r y
r e s e a r c h p r o j e c t i n c l u d e s flight and ground t e s t i n g to d e t e r m i n e the flight
and w e a t h e r conditions which m a y l e a d to altitude m i s i n f o r m a t i o n . A
s e c o n d a r y objective is to c o m p a r e the w a t e r ingestion r e s i s t a n c e of e x i s t ing s t a t i c p o r t s with s t a t i c p o r t s being c o n s i d e r e d f o r f u t u r e a i r c r a f t . The
flight t e s t p o r t i o n of t h i s p r o j e c t h a s begun, and ground t e s t s w i l l be p r e d i c a t e d on the r e s u l t s of the flight t e s t s ,
6/
-
The DC-9-30 a i r c r a f t w a s modified to i n c o r p o r a t e a s i m u l a t e d DC-9-10
s t a t i c s y s t e m , It w a s flown a t S e r i e s 10 VRef 45 knots, with the g e a r down,
50° f l a p s , and s l a t s c l o s e d , to g a t h e r the DC-9-10 data.
7/
Landing g e a r down, s l a t s and flaps e x t e n d e d , and VRef 45 knots.
- 13 -
The c a p t a i n ' s altimeter (type E42459 10 113, S / N 115) and the
first o f f i c e r ' s a l t i m e t e r (type A40179 10 020, S / N 430), both f r o m
N97S, w e r e t a k e n t o the m a n u f a c t u r e r ' s f a c i l i t y w h e r e a d e t a i l e d
t e a r d o w n w a s m a d e . The c a p t a i n ' s b a r o m e t r i c s e t t i n g c o u n t e r w a s
d e t e r m i n e d t o be r e a d i n g a p p r o x i m a t e l y 29.67. The s y n c h r o t e l r e a d ing on a s e r v o e d angle p o s i t i o n i n d i c a t o r w a s 3.65O. T h i s w a s c a l c u l a t e d t o r e p r e s e n t a n indication of a p p r o x i m a t e l y 568 f e e t ; however,
the r o t o r being m e a s u r e d w a s f r e e t o r o t a t e . The o u t e r and i n n e r d r u m s
of the a s s e m b l y , which w e r e held in p r o p e r a l i g n m e n t by light s p r i n g
t e n s i o n , w e r e d i s p l a c e d s o a s t o indicate a n o f f s e t of a p p r o x i m a t e l y 600
feet. A small a r e a of paint w a s m i s s i n g f r o m t h e d r u m a t a n indicated
altitude of a p p r o x i m a t e l y 1 , 2 5 0 feet. T h i s mark w a s v e r y similar i n
s i z e and l o c a t i o n t o the d r u m index, but t h e r e w a s no paint a d h e r i n g t o
the u n d e r s i d e of the d r u m index,
The first o f f i c e r ' s a l t i m e t e r w a s d e t e r m i n e d t o have b e e n s e t at a
b a r o m e t r i c s e t t i n g between 29.73 and 29.24. The d i s p l a c e m e n t f r o m
n o r m a l a l i g n m e n t between the o u t e r and i n n e r d r u m w a s equivalent t o
a p p r o x i m a t e l y 3 , 0 0 0 feet. N o i m p a c t m a r k s could be found on the alt i m e t e r d i a l , but a p o r t i o n of the d i a l next t o the d r u m window r e v e a l e d
a n a r e a , similar i n s h a p e t o the p o i n t e r tip, which had b e e n p r o t e c t e d
f r o m h e a t d a m a g e e v i d e n t o n the s u r r o u n d i n g a r e a , T h e o r i e n t a t i o n of
the p r o t e c t e d a r e a indicated that the needle would have to have b e e n
e i t h e r d i s t o r t e d o r dislodged p r i o r t o the h e a t d a m a g e in o r d e r t o m a s k
this a r e a of the dial. The m a s k e d a r e a w a s n e a r the o u t e r d i a l hash
m a r k indicating ' I 3'I.
A t e s t p r o g r a m w a s conducted by the K o l l s m a n I n s t r u m e n t C o r p o r a tion t o d e t e r m i n e the e f f e c t on a n a l t i m e t e r of (1) a 135O r o l l about the
longitudinal axis of the a i r c r a f t and ( 2 ) sudden stoppage f r o m i m p a c t
d u r i n g a r o l l . The a l t i m e t e r , mounted on a n a l u m i n u m b a r , 24 i n c h e s
f r o m the point of r o t a t i o n , i n a s t a n d a r d i n s t r u m e n t p a n e l cutout, w a s
s e t at 875 f e e t and 29.67. It w a s r o t a t e d about the o f f s e t axis at v a r y i n g
s p e e d s f r o m 18O/second t o 90°/second. N o significant p o i n t e r t r a v e l
w a s noted due t o r o t a t i o n . Next,the a l t i m e t e r w a s allowed t o f r e e fall
f r o m v a r i o u s h e i g h t s t o a s u d d e n s t o p , The s t o p w a s a d j u s t e d t o s t r i k e
the a l t i m e t e r housing a t the r e a r , midpoint, and p a n e l on s u c c e s s i v e
drops.
The indicated altitude i n c r e a s e d to a p p r o x i m a t e l y 1, 000 f e e t on e a c h
o c c a s i o n , and w a s as high as 1 , 2 3 0 f e e t on one d r o p f r o m a height of 10
i n c h e s . The t e s t w a s discontinued at this point t o avoid damage to the
i n s t r u m e n t b e c a u s e the e s t i m a t e d s h o c k v a l v e s w e r e a p p r o x i m a t e l y 50 g ' s ,
and the indicated valve c o m p a r e d f a v o r a b l y w i t h t h a t found on the c a p t a i n ' s
altimeter drum.
-
14 -
1. 16
Other
The Southern Airways DC-9 Operating Manual e s t a b l i s h e d the
p r o c e d u r e s t o be followed i n t h e i r o p e r a t i o n of DC-9 a i r c r a f t . The
nonprecision a p p r o a c h w a s p r e s e n t e d g r a p h i c a l l y with annotations
d e s c r i b i n g c r e w a c t i o n s t o be t a k e n at the a p p r o p r i a t e t i m e s , as
follows:
1.
Complete in-range c h e c k l i s t 10 m i n u t e s p r i o r t o
e s t i m a t e d t i m e of a r r i v a l .
2.
S e l e c t 15' f l a p s , extend slats, and slow to a p p r o p r i a t e
m a n e u v e r i n g s p e e d p r i o r t o c o m m e n c i n g approach.
3.
C o m m e n c e p r o c e d u r e t u r n 30 s e c o n d s p a s t o u t e r
m a r k e r (depending on wind).
4.
Select 25' f l a p s , extend g e a r , c o m p l e t e landing checklist and slow to a p p r o p r i a t e m a n e u v e r i n g speed.
5.
O v e r r a d i o f i x start d e s c e n t t o MDA, m a i n t a i n p r e v i o u s
rnaneuve r i n g speed.
6.
Select 50' f l a p s , slow t o VRef
sighted.
4 5 knots when runway is
7. Reduce t h r u s t slowly o v e r t h r e s h o l d t o obtain VRef ,speed,
touchdown t a r g e t is 1, 000 feet f r o m t h r e s h o l d ,
The Before Landing F i n a l C h e c k l i s t w a s d e s c r i b e d , in p a r t , as
follows :
GEAR ( B o t h p i l o t s )
DOWN/3 GREEN
DOOR LIGHTS OUT
PRESSURE AND QUANTITY NORMAL
500' FLAG SCAN
SPEED
RATE DESCENT
CHECKED
The Southern A i r w a y s DC-9 Flight Manual r e q u i r e d the pilot not
flying the a i r p l a n e t o m a k e the following c a l l o u t s during approaches:
-
15
-
a.
Any deviation below published t r a n s i t i o n a l t i t u d e s .
b.
500' above field e l e v a t i o n and s t a t e "No F l a g s " o r
" F l a g s On" a s s e e n on i n s t r u m e n t .
c.
1 0 0 ' above m i n i m u m s .
d.
At m i n i m u m s , c a l l out "Minimums-Runway i n Sight" o r
"Minimums -No Runway. "
e.
Any s i n k r a t e of 1 , 0 0 0 f e e t / m i n u t e o r m o r e .
The m a n u a l a l s o s t a t e d t h a t d e s c e n t r a t e s in e x c e s s of 1, 000 f e e t /
minute and flat a p p r o a c h e s w e r e t o be avoided, The p r o c e d u r e f o r
e i t h e r a m i s s e d - a p p r o a c h o r a r e j e c t e d landing w a s the s a m e :
1.
Set takeoff power.
2.
Rotate i m m e d i a t e l y t o s t o p d e s c e n t ( m i n i m u m l o o ) and
simultaneously call flaps 15O.
3.
Continue a s i n n o r m a l takeoff.
4. Do not r a i s e g e a r u n t i l c l i m b is e s t a b l i s h e d .
The r a d i o a l t i m e t e r s y s t e m w a s d e s c r i b e d i n Southern A i r w a y s DC-9
O p e r a t i n g Manual i n g e n e r a l t e r m s , including the following, "Two s e p a r a t e
r a d i o a l t i m e t e r s y s t e m s on the ( D a s h 31) . ,
a r e p r o v i d e d t o obtain
p r e c i s e altitude i n f o r m a t i o n above the ground at the m i n i m u m d e c i s i o n ( s i c )
altitude (MDA). T h i s i n f o r m a t i o n is e s s e n t i a l t o the pilot i n h i s d e c i s i o n
The chief pilot f o r S o u t h e r n
t o land o r initiate a g o - a r o u n d m a n e u v e r .
A i r w a y s t e s t i f i e d that t h i s s t a t e m e n t w a s m i s l e a d i n g t h a t it w a s e x c e r p t e d
f r o m the DACO DC-9 m a n u a l , and w a s m o r e applicable to p r e c i s i o n a p p r o a c h e s o v e r l e v e l t e r r a i n than to n o n p r e c i s i o n a p p r o a c h e s of t h i s type.
He e m p h a s i z e d that S o u t h e r n ' s pilots w e r e cautioned i n t r a i n i n g a g a i n s t
using the r a d i o a l t i m e t e r as a p r i m a r y r e f e r e n c e . In amplifying theik
t r a i n i n g p r o c e d u r e , he a l s o indicated t h a t t h e pilots w e r e t r a i n e d t o c a l l
out a l t i t u d e s i n t e r m s of m. s , 1. e x c e p t the "hundred above" and l ' m i n i m u m s l l
w h i c h w e r e obviously r e f e r e n c e d t o MDA. The 500-foot flag s c a n w a s
r e q u i r e d on all a p p r o a c h e s , w h e t h e r v i s u a l o r i n s t r u m e n t , and a c o m p r e hensive s t a n d a r d i z a t i o n p r o g r a m w a s conducted. He s t a t e d t h a t he w a s
not a w a r e t h a t a n y c o m p a n y pilots deviated f r o m t h i s p r a c t i c e . He
.
-
16
-
e s t i m a t e d that m o r e than half of the a p p r o a c h e s m a d e in t h e i r line
operation w e r e nonprecision,
On J a n u a r y 1 2 , 1971, Southern A i r w a y s i s s u e d changes to t h e i r
DC-9 O p e r a t i n g Manual as follows:
( 1 ) A note w a s added to the N o n p r e c i s i o n A p p r o a c h and
Landing D i a g r a m s t a t i n g that, f o r a s h o r t a p p r o a c h
w h e r e t i m e e x p i r a t i o n and MDA f o r the a p p r o a c h a r e
e x p e c t e d to coincide, flaps m a y be extended to 50° a t
the a p p r o a c h f i x .
( 2 ) A n additional callout at 500 f e e t above m i n i m u m altitude
w a s added.
( 3 ) The d i s c u s s i o n on u s e of the r a d i o a l t i m e t e r w a s modified
t o include a w a r n i n g that the s y s t e m w a s u n r e l i a b l e o v e r
hilly o r rolling t e r r a i n , and should not be u s e d f o r altitude
information.
Southern A i r w a y s ' a u t h o r i t y f o r c h a r t e r o p e r a t i o n s w a s contained in
i t s O p e r a t i o n Specifications, T h i s a u t h o r i t y r e q u i r e d that any "off-route"
o p e r a t i o n be a c c o m p l i s h e d a s p r e s c r i b e d by P a r t 121 of the F e d e r a l Aviation Regulations applicable t o s u p p l e m e n t a l air c a r r i e r s and c o m m e r c i a l
o p e r a t o r s , and by the e x c e p t i o n s which w e r e contained i n t h e i r O p e r a t i o n s
Specifications. The exception applicable to I F R takeoff and landing
w e a t h e r m i n i m a r e q u i r e d t h a t , when the p i l o t - i n - c o m m a n d w a s not
qualified f o r the a i r p o r t , he m u s t u s e the w e a t h e r m i n i m a and i n s t r u m e n t
a p p r o a c h p r o c e d u r e s p r e s c r i b e d in P a r t 97 of the F e d e r a l Aviation Regulations. The m i n i m a e s t a b l i s h e d f o r a l o c a l i z e r a p p r o a c h , by this p a r t
of the r e g u l a t i o n s , w e r e 3 5 0 f e e t and 1 m i l e , However, the m i n i m a
specifically established for supplemental a i r c a r r i e r s o r c h a r t e r
o p e r a t i o n s a t the T r i - S t a t e A i r p o r t w e r e 412 f e e t and 1 m i l e .
The a i r p o r t and route qualifications applicable to the c h a r t e r flight
in t h i s instance w e r e s t a t e d in P a r t 121. 445 a s follows:
" ( a ) E a c h s u p p l e m e n t a l air c a r r i e r and c o m m e r c i a l o p e r a t o r
s h a l l e s t a b l i s h in its m a n u a l a p r o c e d u r e w h e r e b y e a c h
pilot who h a s not flown o v e r a route and into a n a i r p o r t
within the p r e c e d i n g 6 0 d a y s w i l l c e r t i f y on a f o r m provided
by the o p e r a t o r that he h a s studied and knows the s u b j e c t s
l i s t e d in p a r a g r a p h (b) of t h i s s e c t i o n in r e g a r d to the r o u t e s
and a i r p o r t s into which he i s to o p e r a t e .
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17
-
" ( b ) E a c h qualifying pilot shall show t h a t he has adequate
knowledge of t h e following:
W e a t h e r c h a r a c t e r i s t i c s a p p r o p r i a t e t o the
seasons.
Navigation f a c i l i t i e s .
Communication procedures.
Kinds of t e r r a i n and o b s t r u c t i o n h a z a r d s ,
M i n i m u m safe flight l e v e l s .
P e r t i n e n t air t r a f f i c c o n t r o l p r o c e d u r e s including
t e r m i n a l a r e a , a r r i v a l , d e p a r t u r e , and holding
and all kinds of i n s t r u m e n t a p p r o a c h p r o c e d u r e s ,
C o n g e s t e d a r e a s , o b s t r u c t i o n , and p h y s i c a l layout
of e a c h a i r p o r t in the t e r m i n a l a r e a i n w h i c h the
pilot w i l l o p e r a t e ,
In a c c o r d a n c e w i t h the c o m p a n y ' s O p e r a t i o n s Manual, when the
c a p t a i n signed the f l i g h t r e l e a s e , he c e r t i f i e d that he had studied and
knew the s u b j e c t s l i s t e d above w i t h r e g a r d t o the r o u t e and a i r p o r t s
into which he intended t o o p e r a t e . T h e r e w a s , h o w e v e r , no p r o c e d u r e
in the m a n u a l t o provide f o r a showing by the c a p t a i n t h a t he had the
r e q u i s i t e knowledge.
,
The a i r p o r t and r o u t e qualifications a p p l i c a b l e t o s c h e d u l e d flights
of S o u t h e r n A i r w a y s a r e contained in Part 121.443. T h i s p a r t c o n t a i n s
the a b o v e - l i s t e d r e q u i r e m e n t s of Part 121.445 and a l s o i n c l u d e s the
following:
( 1 ) He m u s t show a d e q u a t e knowledge of p o s i t i o n r e p o r t i n g
points and holding p r o c e d u r e s . T h i s m a y be d e m o n s t r a t e d
i n a p r o p e r l y equipped s y n t h e t i c t r a i n e r ,
( 2 ) He m u s t m a k e a n e n t r y , as a m e m b e r of the f l i g h t c r e w , at
e a c h r e g u l a r , provisional, and refueling a i r p o r t into which
he is s c h e d u l e d t o fly. The e n t r y m u s t include a takeoff
and a landing, and the qualifying pilot m u s t occupy a s e a t
in the pilot c o m p a r t m e n t , and m u s t be a c c o m p a n i e d by a
pilot who is qualified f o r the a i r p o r t ,
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18
-
( 3 ) The e n t r y r e q u i r e m e n t s m a y be waived if the i n i t i a l
e n t r y is m a d e u n d e r V F R w e a t h e r conditions; o r if the
a i r c a r r i e r shows that s u c h qualification c a n be m a d e
using a p p r o v e d p i c t o r i a l m e a n s ; o r if the A d m i n i s t r a t o r
is notified that the a i r c a r r i e r intends to o p e r a t e into a n
a i r p o r t n e a r one into which the pilot c o n c e r n e d i s c u r r e n t l y
qualified, and the A d m i n i s t r a t o r finds that s u c h qualification is adequate f o r the new a i r p o r t , c o n s i d e r i n g a t l e a s t
the p i l o t ' s f a m i l i a r i t y w i t h the layout, s u r r o u n d i n g t e r r a i n ,
location of o b s t a c l e s , and i n s t r u m e n t a p p r o a c h and t r a f f i c
c o n t r o l p r o c e d u r e s a t the new a i r p o r t ,
The o r i g i n a l negotiations between M a r s h a l l U n i v e r s i t y and Southern
A i r w a y s r e s u l t e d in i n i t i a l r e j e c t i o n by Southern A i r w a y s b e c a u s e of the
takeoff weight l i m i t a t i o n s of t h e i r a i r c r a f t . The s u b s e q u e n t negotiations
r e s u l t e d in a r e d u c t i o n in the weight of p a s s e n g e r s and baggage to be
c a r r i e d f r o m a p p r o x i m a t e l y 1 9 , 5 0 0 pounds to 1 7 , 5 0 0 pounds, and the
c h a r t e r flight w a s scheduled. The flight w a s t h e n o f f e r e d f o r bid to the
pilots and a s s i g n e d on the b a s i s of s e n i o r i t y , the s a m e as r e g u l a r l y
scheduled flights.
The flight w a s d i s p a t c h e d initially f r o m A t l a n t a f o r the e n t i r e c h a r t e r
sequence to Baton Rouge. At Kinston, the c a p t a i n c o n t a c t e d the d i s p a t c h e r
i n Atlanta and a n update w a s a c c o m p l i s h e d by telephone. Both r e l e a s e s
anticipated a landing on a w e t runway a t Huntington, and the 15 p e r c e n t
additional runway r e q u i r e m e n t w a s included i n the landing distance
computations.
The s a m e a i r c r a f t , d i s p a t c h e r s , flight planning s e r v i c e s , and
s u p e r v i s i n g p e r s o n n e l w e r e u s e d in the c h a r t e r o p e r a t i o n a s in the
r e g u l a r l y s c h e d u l e d s e r v i c e . In addition, a c h a r t e r c o o r d i n a t o r w a s
a s s i g n e d to a s s i s t the f l i g h t c r e w in a d m i n i s t r a t i v e m a t t e r s g e n e r a l l y
involving ground o p e r a t i o n s . The c o o r d i n a t o r ' s d u t i e s involved s u p e r vising and expediting ground o p e r a t i o n s , a r r a n g i n g f o r fueling, c o m p l e t ing weight and balance f o r m s , e t c . In the p e r f o r m a n c e of t h e s e duties,
he n o r m a l l y c o m m u n i c a t e d d i r e c t l y with the c a p t a i n s h o r t l y b e f o r e l a n d ing. Although he w a s p e r m i t t e d to e n t e r the cockpit u n d e r these c i r c u m s t a n c e s , h e w a s not a u t h o r i z e d to occupy the j u m p s e a t . In t h i s
instance, the c h a r t e r c o o r d i n a t o r w a s in the cockpit d u r i n g the i n s t r u m e n t
a p p r o a c h , and d i s c u s s e d the fueling a t Huntington, He a l s o c o m m e n t e d ,
"Bet'11 be a m i s s e d - a p p r o a c h " a p p r o x i m a t e l y 16 s e c o n d s b e f o r e impact.
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19
-
During the investigation, c o n s i d e r a b l e attention w a s focused on
the height of the t r e e s on the h i l l w h e r e initial i m p a c t o c c u r r e d . It
was d e t e r m i n e d by a n FAA Runway O b s t r u c t i o n Survey, dated D e c e m b e r 1, 1970, that s e v e r a l t r e e s on the h i l l p e n e t r a t e d the ILS a p p r o a c h
s u r f a c e 8 / and t h e r e f o r e constituted o b s t r u c t i o n s t o a i r navigation a s
defined
P a r t 77, Subpart C, of the F e d e r a l Aviation Regulations.
However, t h e s e s t a n d a r d s a r e u s e d in ( 1 ) a d m i n i s t e r i n g the F e d e r a l - A i d
A i r p o r t P r o g r a m , ( 2 ) t r a n s f e r r i n g p r o p e r t y u n d e r Section 16 of the
F e d e r a l A i r p o r t Act, ( 3 ) providing t e c h n i c a l advice in a i r p o r t d e s i g n
and development, and ( 4 ) imposing r e q u i r e m e n t s f o r public notice of
c o n s t r u c t i o n o r a l t e r a t i o n of s t r u c t u r e s w h e r e notice w i l l p r o m o t e air
s a f e t y . The c r i t e r i a u s e d i n the e s t a b l i s h m e n t of flight p r o c e d u r e s and
a i r c r a f t o p e r a t i o n a l l i m i t a t i o n s a r e contained in P a r t 97 and the U. S.
Standard f o r T e r m i n a l I n s t r u m e n t Approach P r o c e d u r e ( T E R P S ) . P a r a g r a p h 954 of T E R P S r e q u i r e s that the m i n i m u m o b s t a c l e c l e a r a n c e in
the f i n a l a p p r o a c h a r e a 9 / shall be 250 f e e t f o r a l o c a l i z e r approach.
The t r e e s did not violate-this r e q u i r e m e n t ,
A pen r e c o r d i n g w a s m a d e of the o u t e r m a r k e r identifier signals as
they w e r e r e c o r d e d i n the CVR t a p e , to a s s i s t in locating the flightpath
of SOU 932 through the r a d i a t i o n p a t t e r n . F o r the p u r p o s e of this evaluation, i t w a s a s s u m e d that the r e c e i v e r s e n s i t i v i t y of the DC-9 w a s the
same as that of the FAA flight-check a i r c r a f t , It w a s a l s o a s s u m e d that
the identification tone had r e a c h e d i t s m a x i m u m s i g n a l s t r e n g t h when the
r e c o r d e d s i g n a l stopped. B a s e d on the calculations, i t w a s d e t e r m i n e d
that the a i r c r a f t w a s a p p r o x i m a t e l y 1 , 8 5 0 feet south of the o u t e r m a r k e r
t r a n s m i t t e r when the s i g n a l stopped. Any v a r i a t i o n in t h e s e a s s u m p t i o n s
would, of fiecessity, place the a i r c r a f t c l o s e r to the t r a n s m i t t i n g antenna
than depicted on Attachment 1.
Part 7 7 , 2 7 ( b ) defines ILS a p p r o a c h s u r f a c e as a s u r f a c e longitudinally
c e n t e r e d on the extended c e n t e r l i n e of an ILS runway beginning a t e a c h end
of the p r i m a r y s u r f a c e and extending outward and upward at a slope of 50
t o 1 f o r a h o r i z o n t a l d i s t a n c e of 10, 000 f e e t and at a slope of 40 to 1 f o r a n
additional 40, 000 feet. T h i s s u r f a c e is the width of the p r i m a r y s u r f a c e
at the beginning and expands u n i f o r m l y t o a width of 16, 000 f e e t a t a distance
of 50,000 f e e t f r o m the end of the p r i m a r y s u r f a c e , The p r i m a r y s u r f a c e
of Runway 11 w a s 1 , 0 0 0 f e e t wide and extended 200 f e e t beyond the threshold
at e a c h end of the runway.
8/
9/
P a r a g r a p h 930(1) gives the d i m e n s i o n s f o r the final a p p r o a c h a r e a a s
50,000 f e e t long m e a s u r e d outward along the final a p p r o a c h c o u r s e f r o m
a point 200 f e e t outward f r o m the runway t h r e s h o l d , and 1 , 0 0 0 f e e t wide
at that point expanding u n i f o r m l y along the l o c a l i z e r c o u r s e t o a width
of 16, 000 f e e t at a point 50, 000 feet f r o m the beginning point.
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20
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2.
2. 1
ANALYSIS AND CONCLUSIONS
Analysis
The a i r c r a f t c e n t e r of g r a v i t y w a s within allowable l i m i t s . B a s e d on
t h e a i r c r a f t p e r f o r m a n c e capability, t h e r e w a s sufficient runway a v a i l a b l e
f o r N97S to have l a n d e d u n d e r t h e conditions e x i s t i n g a t Huntington a t t h e
t i m e of t h e a c c i d e n t .
The c r e w w a s p r o p e r l y c e r t i f i c a t e d a n d qualified f o r t h e flight. The
a i r c r a f t had been m a i n t a i n e d i n a c c o r d a n c e w i t h existing company p r o c e d u r e s and t h e F e d e r a l Aviation Regulations. The i n v e s t i g a t i o n d i s c l o s e d
no malfunction o r f a i l u r e i n t h e a i r c r a f t s t r u c t u r e , p r i m a r y flight c o n t r o l s ,
o r powerplants.
The B o a r d r e v i e w e d t h e c h a r t e r a r r a n g e m e n t s , o p e r a t i o n s s p e c i f i c a t i o n s , and r e g u l a t i o n s governing t h e d i s p a t c h a n d conduct of t h i s flight.
Although t h e flight w a s conducted i n a c c o r d a n c e with t h e p r e s c r i b e d p r o c e d u r e s , t h e r e i s o n e a r e a which i s of c o n c e r n to t h e Board. An equivalent
l e v e l of s a f e t y f o r "off r o u t e " o p e r a t i o n s , ofithe type involved i n t h i s a c c i dent, is t h e o r e t i c a l l y a c h i e v e d by t h e i n c r e a s e d landing m i n i m a a p p l i c a b l e
to s u c h o p e r a t i o n s . However, t h e c r e w r e q u i r e m e n t s f o r "off r o u t e " a i r p o r t
qualification do not r e q u i r e t h e s a m e d e g r e e of qualification a s t h a t r e q u i r e d
f o r s c h e d u l e d o p e r a t i o n s . The r e a s o n f o r t h i s i s t h a t it would not b e p r a c t i c a l to r e q u i r e a n a c t u a l e n t r y i n t o & v e r y p o s s i b l e "off r o u t e " a i r p o r t , n o r
would it be p r a c t i c a l to have o n hand t h e a p p r o v e d p i c t o r i a l d i s p l a y f o r e v e r y
p o s s i b l e ,"off r o u t e " a i r p o r t . N e v e r t h e l e s s , t h e B o a r d b e l i e v e s t h a t a m o r e
p o s i t i v e m e a n s f o r d e t e r m i n i n g t h a t a pilot i s qualified to m a k e a n i n i t i a l
e n t r y into a n "off r o u t e " a i r p o r t should b e e s t a b l i s h e d by t h e FAA a n d t h e a i r
c a r r i e r s . The c o m p a n y ' s o p e r a t i o n s m a n u a l p r o v i d e s t h a t a l l a pilot is r e q u i r e d to do f o r qualification is to s i g n a flight r e l e a s e f o r m indicating t h a t
he h a s s t u d i e d and knows t h e i t e m s e n u m e r a t e d in F A R 121.445. By
c o m p a r i s o n , F A R 121.443, which a p p l i e s t o s c h e d u l e d o p e r a t i o n s , r e q u i r e s
t h a t t h e p i l o t - i n - c o m m a n d , b e f o r e making h i s i n i t i a l e n t r y into a n a i r p o r t
u n d e r I F R conditions, m u s t d e m o n s t r a t e t h a t he h a s a d e q u a t e knowledge, 'by
a c t u a l e n t r y into t h a t a i r p o r t , by e n t r y into a n e a r b y a i r p o r t , by s y n t h e t i c
t r a i n e r , o r by u s e of a p p r o v e d p i c t o r i a l d i s p l a y s .
T h e r e is no e v i d e n c e i n t h i s c a s e to i n d i c a t e t h a t t h e c r e w had not
sufficiently f a m i l i a r i z e d i t s e l f with t h e Huntington a i r p o r t , s u r r o u n d i n g
t e r r a i n , a n d t h e a p p r o a a h a n d landing p r o c e d u r e s . At the s a m e t i m e , t h e r e
is no way to a s s u r e t h a t t h e c r e w h a d a c t u a l knowledge of t h e foregoing p r i o r
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to d e p a r t u r e , s i n c e they w e r e not r e q u i r e d t o d e m o n s t r a t e positively s u c h
knowledge. Accordingly, t h e B o a r d b e l i e v e s t h a t t h e p r o c e d u r e s should be
r e v i s e d to r e q u i r e t h a t pilots d e m o n s t r a t e by s o m e m e a n s (2.g., a n o r a l
o r w r i t t e n t e s t o r e x a m i n a t i o n o t h e r than signing t h e flight r e l e a s e ) t h a t they
a r e f a m i l i a r with t h e "off r o u t e " a i r p o r t into which they will o p e r a t e .
E/
T h e flightpath and p r o f i l e ( A t t a c h m e n t 1) show t h a t t h e a i r c r a f t . des c e n d e d through t h e MDA a p p r o x i m a t e l y 2 m i l e s f r o m t h e end of t h e runway
and t h a t s u c h d e s c e n t w a s not c o r r e c t e d i n t i m e to avoid i m p a c t with t h e
t r e e s . The m a j o r t h r u s t of t h e i n v e s t i g a t i o n w a s f o c u s e d o n uncovering t h e
r e a s o n o r r e a s o n s which m i g h t explain t h i s d e s c e n t .
The r e l a t i v e l y s t a b l e d e s c e n t depicted by t h e flight r e c o r d e r a l t i t u d e
t r a c e does not s u g g e s t t h a t a l o s s of c o n t r o l o r autopilot "runaway" w a s
e x p e r i e n c e d during t h e a p p r o a c h . However, c o n v e r s a t i o n between t h e p i l o t s
a t a p p r o x i m a t e l y 1931 and 1934 e x p r e s s e d c o n c e r n with t h e p e r f o r m a n c e of
t h e autopilot. The c a p t a i n ' s c o m m e n t a t 1931, ("that thing c a p t u r e d ! How
did it c a p t u r e ? ' I ) e x p r e s s e d s u r p r i s e t h a t t h e autopilot h a d a p p a r e n t l y c a p t u r e d a glide s l o p e s i g n a l when t h e r e w a s no signal. The glide s l o p e c a p t u r e
probably r e s u l t e d b e c a u s e t h e c a p t a i n t u r n e d t h e autopilot NAV S E L E C T
switch to ILS r a t h e r than to e i t h e r MAN G / P o r NAV LOC, which should b e
u s e d o n a l o c a l i z e r a p p r o a c h . Since t h e autopilot c o n t r o l s t h e a i r c r a f t o n
t h e g l i d e s l o p e by maintaining a n u l l signal, t h e t o t a l a b s e n c e of a glide
s l o p e signal, a s i n t h i s c a s e , would have r e s u l t e d i n a n a u t o m a t i c 700 to 800
f e e t / m i n u t e d e s c e n t . Subsequent i n c r e a s e s i n t h e r a t e of d e s c e n t i n d i c a t e
t h a t t h e NAV SELECT switch w a s t u r n e d to a p r o p e r position. The l a t e r
c o m m e n t a t a p p r o x i m a t e l y 1934, ("This autopilot a i n ' t r e s p o n d i n g j u s t
- sluggish") i n d i c a t e s d i s s a t i s f a c t i o n with t h e p e r f o r m a n c e of
right
t h a t component, but t h e c a p t a i n did not specify i n which a x i s , o r i n what
m a n n e r , it w a s "sluggish. ' I An a n a l y s i s of heading and a l t i t u d e t r a c e s of t h e
flight r e c o r d e r i n d i c a t e s t h a t t h e autopilot w a s u s e d to m a i n t a i n a c o u r s e i n bound o n t h e l o c a l i z e r and to d e s c e n d t h e a i r c r a f t during a t l e a s t two p e r i o d s
of t h e i n s t r u m e n t a p p r o a c h . Notwithstanding t h e c a p t a i n ' s c o m m e n t s , both
of which w e r e m a d e while t h e flight w a s i n t h e vicinity of t h e o u t e r m a r k e r ,
t h e r e i s no indication of any h a z a r d o u s situation. Although t h e c a p t a i n ' s
attention to t h e o p e r a t i o n of t h e autopilot to t h e e x t e n t r e f l e c t e d by t h e s e
r e m a r k s could have d e t r a c t e d f r o m h i s n o r m a l i n s t r u m e n t s c a n , t h e r e is no
evidence to s u g g e s t t h a t t h e autopilot w a s m i s u s e d o r t h a t it had any d i r e c t
b e a r i n g on t h e accident.
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10/
A r e c o m m e n d a t i o n to t h e above effect i s s e t f o r t h h e r e i n a f t e r , i n t h e
R e c o m m e n d a t i o n s section.
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One a r e a which the B o a r d c a r e f u l l y c o n s i d e r e d i s t h e extent to which
the final s t a g e s of the d e s c e n t w e r e influenced by v i s u a l r e f e r e n c e to l i g h t s
on t h e s u r f a c e . C o n v e r s a t i o n between the c a p t a i n a n d first o f f i c e r during
the 10-second p e r i o d preceding MDA p a s s a g e i n d i c a t e s t h a t they w e r e beginning to s e e the l i g h t s on the ground, o r a t l e a s t the glow of the l i g h t s . It
i s p o s s i b l e t h a t the sighting of t h e s e l i g h t s , i n combination with t h e knowledge t h a t they w e r e approaching the bottom of t h e l o w e s t cloud l a y e r , could
have induced t h e c a p t a i n to continue t h e d e s c e n t below MDA i n o r d e r to s e e
the runway e n v i r o n m e n t a t t h e e a r l i e s t m o m e n t . The descent, i n fact, did
continue through t h i s p e r i o d , a n d ground w i t n e s s e s o b s e r v e d the a i r c r a f t
c l e a r of clouds i n t h i s a r e a .
It is a l s o p o s s i b l e t h a t the conduct of t h e a p p r o a c h could have been
affected by a v i s u a l i l l u s i o n produced by t h e d i f f e r e n c e i n the elevation of
the r e f i n e r y a n d t h e a i r p o r t . Approximately 2 miles f r o m t h e runway, t h e
flight was approaching the b r i g h t l i g h t s s u r r o u n d i n g the r e f i n e r y and, a s
noted above, the c r e w w a s d i s c u s s i n g a t l e a s t t h e glow, and probably fleeting g l i m p s e s , of ground l i g h t s through t h e broken clouds. A s the d e s c e n t
continued, the opportunity f o r ground r e f e r e n c e through s c a t t e r e d clouds
would have i n c r e a s e d . Below a p p r o x i m a t e l y 1, 100 f e e t m. s . l . , the r e p o r t e d cloud b a s e , the only r e s t r i c t i o n to visibility should have been t h e
fog, s m o k e , and l i g h t r a i n .
If the a p p r o a c h l i g h t s o r s e q u e n c e f l a s h e r l i g h t s w e r e sighted while the
r e f i n e r y l i g h t s w e r e still i n the field of vision, with no a p p r e c i a b l e l i g h t s
between, the pilots would have mentally v i s u a l i z e d both l i g h t s o u r c e s a t t h e
s a m e elevation a s the n e a r e r l i g h t s . T h e r e f o r e , t h e height above both l i g h t s
would a p p e a r to be about 700 feet, w h e r e a s the a c t u a l height above t h e
a p p r o a c h l i g h t s would have been only 400 feet, due to t h e 300-foot d i f f e r e n c e
i n elevation between t h e r e f i n e r y and t h e a p p r o a c h lights. A f t e r t h e a i r c r a f t
p a s s e d the r e f i n e r y , the p r e c o n c e i v e d i m a g e would have been r e t a i n e d a n d
the v i s u a l c u e s would have told the c r e w t h a t they w e r e a p p r o x i m a t e l y 300
f e e t higher than d e s i r e d .
The r e m a i n i n g evidence, however, s t r o n g l y s u g g e s t s t h a t the c r e w
n e v e r obtained v i s u a l c o n t a c t with t h e a p p r o a c h l i g h t s o r with any p a r t of t h e
runway environment. The v i s u a l i l l u s i o n d i s c u s s e d above, f o r example,
would have p r o m p t e d a n i n c r e a s e i n t h e r a t e of descent, which s i g n i f i c a n t l y .
is not r e f l e c t e d on t h e flight data r e c o r d e r . Even m o r e i m p o r t a n t , t h e r e '
w e r e no c o m m e n t s on tne c+it
voice r e c o r d e r p e r t a i n i n g to ground l i g h t s
o t h e r than t h o s e mentioned a s t h e a i r c r a f t p a s s e d o v e r t h e r e f i n e r y . If any
l i g h t s a s s o c i a t e d with the runway e n v i r o n m e n t had been sighted, it c a n be
p r e s u m e d t h a t s o m e mention of t h e sighting would have been made. C e r t a i n l y ,
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s u c h a p r e s u m p t i o n i s f a r m o r e l i k e l y than t h e explanation t h a t t h e 'runway
e n v i r o n m e n t w a s sighted, but t h a t s u c h sighting w a s e i t h e r sufficiently
obvious to n-gate t h e n e e d f o r a c a l l o u t o r was i n d i c a t e d a n d acknowledged
by n o n v e r b a l s i g n a l s .
The r e c o r d e d c o n v e r s a t i o n a l s o i n d i c a t e s t h a t t h e c r e w w a s not a w a r e
t h a t t h e a i r c r a f t had d e s c e n d e d below MDA. The f i r s t o f f i c e r ' s c o m m e n t at
1935:06.8 ( " W e ' r e two h u n d r e d above") i s m o s t logically c o n s t r u e d a s a
r e f e r e n c e to MDA. The following c o m m e n t by t h e c h a r t e r c o o r d i n a t o r
(Bet'll be a m i s s e d approach") c a n be taken to m e a n t h a t t h e flight w a s
a p p r o a c h i n g MDA, y e t t h e runway e n v i r o n m e n t w a s still not i n sight.
The next s t a t e m e n t o n t h e r e c o r d e r ( " F o u r hundred") m o s t probably m e a n s
t h a t the a i r c r a f t h a d r e a c h e d MDA, which i s 400 f e e t above t h e a i r p o r t e l e v a tion. Such a n i n t e r p r e t a t i o n i s c o n s i s t e n t with t h e following r e m a r k of t h e
c a p t a i n ("that t h e a p p r o a c h ? "), which i n d i c a t e s t h a t he w a s asking, p e r h a p s
r h e t o r i c a l l y , w h e t h e r they h a d r e a c h e d t h e f a r t h e s t point to which t h e flight
could l e g a l l y descend. The first o f f i c e r r e s p o n d e d "Yeah, ' I which a g a i n i m p l i e s t h a t t h e MDA had been r e a c h e d and t h e runway e n v i r o n m e n t w a s not i n
sight. The a v a i l a b l e e v i d e n c e a l s o i n d i c a t e s t h a t a l e v e l off o r m i s s e d a p p r o a c h w a s then initiated. The s w a t h c u t t h r o u g h t h e t r e e s , ground w i t n e s s
s t a t e m e n t s , and t h e flight r e c o r d e r a l t i t u d e t r a c e a l l show t h a t t h e d e s c e n t
w a s stopped, power w a s added, and a g r a d u a l c l i m b w a s c o m m e n c e d .
F u r t h e r m o r e , t h e first o f f i c e r c a l l e d o u t a i r s p e e d i n t e r m s of a n u m b e r
("Hundred and twenty-six") i n s t e a d of a r e f e r e n c e s p e e d ("bug p l u s - - - " ) ,
which i s i n d i c a t i v e of a go-around r a t h e r t h a n a continuing a p p r o a c h .
u/
In view of t h e foregoing, t h e B o a r d concludes t h a t the c r e w n e v e r
s i g h t e d t h e runway e n v i r o n m e n t and w a s not a w a r e t h a t t h e flight had des c e n d e d through a c t u a l MDA.
F r o m a study of t h e c o n v e r s a t i o n and a c t i v i t i e s r e f l e c t e d by t h e voice
r e c o r d e r , it is a p p a r e n t that, while t h e a p p r o a c h was conducted i n a s y s t e m a t i c m a n n e r , the c r e w deviated f r o m s o m e of t h e r e q u i r e d p r o c e d u r e s .
With r e s p e c t to r e q u i r e d c a l l o u t s , t h e r e w a s no m e n t i o n t h a t t h e g e a r w a s
down and l o c k e d by e i t h e r pilot. The f i r s t o f f i c e r did not c a l l 500 f e e t above
t h e field elevation with a c h e c k of i n s t r u m e n t f l a g s , s p e e d , and r a t e of
There was a
d e s c e n t a s r e q u i r e d o n t h e B e f o r e Landing F i n a l Checklist.
c a l l , " W e ' r e two h u n d r e d above, l 1 but t h i s did not p r e c l u d e t h e r e q u i r e d
U/ Although t h e c h a r t e r c o o r d i n a t o r w a s not a pilot, it i s l i k e l y t h a t he
would be f a m i l i a r with t h e MDA altitude, due to p r e v i o u s c o n v e r s a t i o n s
i n t h e cockpit, and would a l s o b e a b l e to r e a d a l t i t u d e f r o m t h e c o c k p i t
instruments.
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24
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c a l l s at 100 feet above m i n i m u m s and a t m i n i m u m s , with a p o s i t i v e s t a t e m e n t
at the l a t t e r point a s to w h e t h e r o r not t h e runway w a s in sight. Finally,
t h e r e w a s no r e p o r t t h a t t h e r a t e of d e s c e n t exceeded 1 , 0 0 0 f e e t / m i n u t e , although the r a t e of d e s c e n t f o r t h e 10-second p e r i o d p r i o r to the l e v e l off
w a s 1, 350 f e e t / m i n u t e . 1 2 /
-
A p a r t f r o m the first o f f i c e r ' s deviations with r e s p e c t to c a l l o u t s , t h e
c a p t a i n a l s o deviated f r o m p r e s c r i b e d p r o c e d u r e s by failing to l e v e l off the
a i r c r a f t at o r above what he believed to be MDA. Thus, when t h e first o f f i c e r
c a l l e d out "Two hundred above, I t the c a p t a i n should have a n t i c i p a t e d r e a c h i n g
MDA, and should have taken action to a s s u r e t h a t t h e a i r c r a f t would be
l e v e l l e d off by t h e t i m e t h e a i r c r a f t r e a c h e d MDA. Instead, the captain did
n o t start to r o t a t e t h e a i r c r a f t until s e v e r a l s e c o n d s a f t e r t h e "Four hundred
feet'' callout, with t h e consequence t h a t t h e a i r c r a f t s a n k an additional 90
f e e t b e f o r e the d e s c e n t w a s finally a r r e s t e d .
E/
It i s difficult to a s s e s s the i m p a c t of t h e above deviations on t h e
d e s c e n t of t h e flight below MDA. Although s t r i c t a d h e r e n c e to o p t i m a l
a p p r o a c h p r o c e d u r e s i s of c r i t i c a l i m p o r t a n c e in executing a n o n p r e c i s i o n
a p p r o a c h u n d e r a c t u a l i n s t r u m e n t conditions a n d might have m a d e a d i f f e r e n c e i n t h i s i n s t a n c e , it n e v e r t h e l e s s a p p e a r s t h a t t h e c r e w w a s a w a r e of
altitude, as r e f l e c t e d by t h e cockpit c o n v e r s a t i o n , and i n f a c t i n i t i a t e d a goa r o u n d when they believed they h a d r e a c h e d MDA.
The r e m a i n i n g and c r i t i c a l question is why the d e s c e n t through MDA
w a s not r e c o g n i z e d by t h e c r e w . After c a r e f u l l y studying t h e evidence
b e a r i n g on t h i s question, t h e B o a r d i s of the view t h a t t h e r e a r e only two
r e a s o n a b l y p o s s i b l e explanations.
The f i r s t of t h e s e p o s s i b i l i t i e s is t h a t t h e c r e w w a s using the b a r o m e t r i c a l t i m e t e r s to d e t e r m i n e t h e i r height above MDA and t h e v e r t i c a l
s p e e d i n d i c a t o r s to m o n i t o r t h e r a t e of d e s c e n t during t h e a p p r o a c h , but
t h a t t h e s e i n s t r u m e n t s w e r e providing e r r o n e o u s information. I t i s
The s t a n d a r d p r o c e d u r e of s e l e c t i n g 2 5 O f l a p s until t h e runway w a s i n
s i g h t a l s o w a s not followed, s i n c e the flaps w e r e a p p a r e n t l y l o w e r e d
to 50' at t h e o u t e r m a r k e r . However, t h i s d e c i s i o n by t h e captain
was b a s i c a l l y sound, a s d e m o n s t r a t e d by the s u b s e q u e n t change i n
Southern s p r o c e du r e s
'
.
The flight r e c o r d e r altitude t r a c e r e f l e c t e d a n altitude of 1 , 0 0 5 f e e t
m. s. 1. when the "Four hundred" callout w a s made, w h e r e a s , the
i n i t i a l i m p a c t with t h e trees o c c u r r e d a t 916 f e e t m. s.1.
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25
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p o s s i b l e t h a t a s t a t i c s y s t e m e r r o r c a u s e d t h e b a r o m e t r i c a l t i m e t e r to r e a d
h i g h e r than t h e a c t u a l a l t i t u d e of t h e a i r c r a f t a n d p r o d u c e d a d e c r e a s e i n
t h e i n d i c a t e d r a t e of d e s c e n t on t h e v e r t i c a l s p e e d i n d i c a t o r . In t h e s e c i r c u m s t a n c e s , the pilot would r e d u c e power and p o s s i b l y l o w e r t h e n o s e of t h e
a i r c r a f t i n o r d e r to r e g a i n t h e d e s i r e d r a t e o f d e s c e n t . T h i s i n t u r n would
r e s u l t i n t h e a i r c r a f t ' s being l o w e r than i n d i c a t e d on t h e a l t i m e t e r , and des c e n d i n g a t a r a t e g r e a t e r than t h a t displayed o n t h e v e r t i c a l s p e e d i n d i c a t o r .
T h e e x i s t e n c e of a n e r r o r s u c h a s t h a t d e s c r i b e d above i s c o n s i s t e n t
with c e r t a i n i n d i c a t i o n s on t h e flight data r e c o r d e r . F o r e x a m p l e , t h e r e a r e
s e v e r a l i n c r e a s e s in t h e r a t e of d e s c e n t r e c o r d e d by t h e flight r e c o r d e r
during t h e final a p p r o a c h indicating t h a t t h e c a p t a i n m a y h a v e been a t t e m p t i n g
to c o m p e n s a t e f o r t h e l o w e r - t h a n - a c t u a l r a t e of d e s c e n t . S i n c e t h e s e d e s c e n t
r a t e s w e r e all in e x c e s s of 1, 000 f e e t / m i n u t e , the a b s e n c e of a n y r e q u i r e d
c a l l o u t would s u p p o r t t h e p r e m i s e t h a t t h e v e r t i c a l s p e e d i n d i c a t o r w a s r e flecting a r a t e of d e s c e n t l o w e r than t h e a c t u a l d e s c e n t r a t e . M o r e o v e r ,
d u r i n g t h e l a s t 10 m i n u t e s of flight, t h e r e w e r e two i n s t a n c e s i n which t h e
flight r e c o r d e r r e f l e c t e d d e s c e n t s which r e s u l t e d i n o v e r s h o o t s followed by
g r a d u a l r e t u r n s t o t h e d e s i r e d altitude. We r e c o g n i z e t h a t t h e s e o v e r s h o o t s
m a y h a v e r e s u l t e d f r o m e i t h e r t h e p i l o t ' s technique i n t h e m a n u a l o p e r a t i o n
of h i s flight c o n t r o l s o r t h e u s e of t h e a i r c r a f t autopilot. It is p o s s i b l e , howe v e r , t h a t t h e s e o v e r s h o o t s could be s y m p t o m a t i c of a lagging of t h e a i r c r a f t
i n s t r u m e n t s due to a n e r r o r within t h e s t a t i c s y s t e m s . It is a l s o c o n c e i v a b l e
t h a t t h e r e could b e a n e r r o r i n o n e o r a l l s t a t i c s y s t e m s s u c h t h a t it would
m a n i f e s t i t s e l f while t h e a i r c r a f t w a s descending but not a f t e r l e v e l l i n g off.
The f i r s t of t h e s e d e s c e n t s w a s 175 feet a n d r e s u l t e d i n a n o v e r s h o o t of 50
feet. The s e c o n d d e s c e n t , which o c c u r r e d a t 6 m i n u t e s 7 s e c o n d s b e f o r e
i m p a c t , w a s 575 f e e t with a r e s u l t a n t o v e r s h o o t of 150 feet. Both of t h e s e
o v e r s h o o t s w e r e c o r r e c t e d by a g r a d u a l c l i m b back to t h e d e s i r e d altitude.
The r a t i o of t h e a m o u n t of o v e r s h o o t to t h e t o t a l d e s c e n t i s 0. 286 and 0.261,
r e s p e c t i v e l y , o r 26 to 29 f e e t f o r e a c h 100 f e e t of d e s c e n t . The final d e s c e n t
of 1 , 2 0 0 f e e t with a n a p p a r e n t o v e r s h o o t of 318 f e e t r e s u l t s i n a n e r r o r r a t i o
of 0.265 o r 27 f e e t p e r 100 f e e t of d e s c e n t , which c l o s e l y p a r a l l e l s t h e e r r o r
r a t i o s of t h e two e a r l i e r o v e r s h o o t s .
With r e s p e c t to p h y s i c a l e v i d e n c e p e r t a i n i n g d i r e c t l y t o t h e b a r o m e t r i c
a l t i m e t e r s , it a p p e a r s t h a t both w e r e c o r r e c t l y set a t 29.67, t h e r e b y e l i m i nating any i n d i c a t e d e r r o r f r o m t h a t s o u r c e . The d i s p l a c e m e n t of t h e o u t e r
a n d i n n e r d r u m s , 600 f e e t and 3 , 000 f e e t f o r t h e c a p t a i n ' s and c o p i l o t ' s
b a r o m e t r i c a l t i m e t e r s , r e s p e c t i v e l y , w a s t h e r e s u l t of i m p a c t f o r c e s ' o v e r coming t h e l i g h t s p r i n g t e n s i o n holding t h e m i n place. S i n c e t h e d r u m
a s s e m b l i e s of both a l t i m e t e r s w e r e e s s e n t i a l l y i d e n t i c a l , t h e v a r i a t i o n i n
d i s p l a c e m e n t i s a t t r i b u t e d to t h e d i f f e r e n c e i n i m p a c t f o r c e s e n c o u n t e r e d .
- 26
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Other d a m a g e to the i n t e r n a l m e c h a n i s m of e a c h b a r o m e t r i c a l t i m e t e r p r e cluded positive d e t e r m i n a t i o n of t h e i r o p e r a t i n g capability p r i o r to i m p a c t .
N e v e r t h e l e s s , i f the m a r k a t t h e 1, 250-foot point o n t h e c a p t a i n ' s a l t i m e t e r
d r u m w a s m a d e a t i n i t i a l i m p a c t , the a l t i m e t e r w a s r e a d i n g 300 f e e t
high. S i m i l a r l y , the m a r k i n g on t h e first o f f i c e r ' s a l t i m e t e r could be cons t r u e d to i n d i c a t e a n e r r o r of approximately 300 feet. To p l a c e t h e signific a n c e of t h e s e m a r k i n g s in p r o p e r p e r s p e c t i v e , however, it should be noted
t h a t t e s t s conducted subsequent to t h e a c c i d e n t d e m o n s t r a t e d t h a t t h e 300foot d i f f e r e n c e could have been c a u s e d by i m p a c t f o r c e s .
Finally, evidence supportive of an a l t i m e t e r e r r o r c a n be d e r i v e d
f r o m t h e cockpit v o i c e r e c o r d e r . During the final stages of the d e s c e n t , the
first o f f i c e r m a d e four altitude callouts. A l l of t h e s e c a l l o u t s except the
first, which was m a d e by r e f e r e n c e to t h e ground, w e r e a p p r o x i m a t e l y 200
f e e t higher than the a c t u a l altitude of the a i r c r a f t as r e f l e c t e d by the flight
data recorder.
Since t h e b a r o m e t r i c a l t i m e t e r i s the p r i m a r y s o u r c e
of altitude information, it would be r e a s o n a b l e to a s s u m e t h a t t h e s e callouts
w e r e m a d e by r e f e r e n c e to t h a t i n s t r u m e n t .
E/
The foregoing d i s c u s s i o n c o n s t i t u t e s one p o s s i b l e explanation f o r t h e
unrecognized d e s c e n t through MDA by d e m o n s t r a t i n g how a n e r r o r i n t h e
s t a t i c s y s t e m could m i s l e a d the pilots by c a u s i n g e r r o n e o u s indications on
t h e b a r o m e t r i c a l t i m e t e r s And t h e v e r t i c a l s p e e d i n d i c a t o r s . If s u c h a n
e r r o r did, i n f a c t , o c c u r , then the a l t i m e t e r would have r e a d 200-300 f e e t
high, which i n t u r n would account f o r the f a c t t h a t the c r e w did not a r r e s t
the d e s c e n t until the a i r c r a f t r e a c h e d an altitude of a p p r o x i m a t e l y 916
m. s.1. o r o v e r 300 feet below MDA.
T h e r e i s one r e m a i n i n g f a c t o r which must b e c o n s i d e r e d i n evaluating
the likelihood of an e r r o r i n t h e s t a t i c s y s t e m i n s t r u m e n t s . Since an e r r o r
in the s t a t i c s y s t e m would a l s o affect the i n d i c a t e d a i r s p e e d , t h e B o a r d c a l c u l a t e d the effect of a s t a t i c s y s t e m e r r o r sufficient to c a u s e an i n d i c a t e d
altitude e r r o r of approximately 300 feet. The calculation a s s u m e d t h a t a
s t a t i c p r e s s u r e difference e x i s t e d between a m b i e n t and that s e n s e d by the
a l t i m e t e r so t h a t when the a l t i m e t e r i n d i c a t e d 1 , 2 4 0 feet, t h e a c t u a l altitude
w a s 916 feet. By u s e of a c a l i b r a t e d a i r s p e e d of 130 knots 1 5 / and the
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14/
F o r a c o m p a r i s o n of t h e s e a l t i t u d e s , s e e t h e c h a r t s e t f o r t h below
on page 29.
15/
-
The f i g u r e of 130 knots w a s s e l e c t e d s i n c e t h e evidence c o n f i r m s
t h a t the a i r s p e e d i n s t r u m e n t s w e r e indicating s p e e d s of t h a t magnitude.
The captain s t a t e d t h a t he w a s going to fly t h e [ F o o t n o t e c o n t i n u e d ]
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27
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United S t a t e s S t a n d a r d A t m o s p h e r e Table, p r e s s u r e r a t i o s w e r e d e t e r m i n e d
a n d a p p l i e d to t h e e x i s t i n g QNH 1 6 / f o r t h e a l t i t u d e s 1, 240 a n d 916 feet.
The p r e s s u r e r e q u i r e d a t t h e P i t o t h e a d to g e n e r a t e a n i n d i c a t e d a i r s p e e d of
130 knots a t 1, 240 f e e t w a s a l s o c a l c u l a t e d .
It w a s t h e n a s s u m e d t h a t t h e a i r c r a f t d e s c e n d e d to 916 f e e t and t h a t
t h e s t a t i c s y s t e m continued t o s e n s e a s t a t i c p r e s s u r e equivalent t o 1, 240
f e e t , a n d t h e pilot c o n t r o l l e d h i s a i r c r a f t so a s to m a i n t a i n a n i n d i c a t e d a i r s p e e d of 130 knots. T h i s would r e q u i r e a c o n s t a n t R t o t s y s t e m p r e s s u r e .
With t h e s e conditions, i t w a s found t h a t a t 916 feet, when t h e i n d i c a t e d a i r s p e e d w a s m a i n t a i n e d a t 130 knots, t h e a c t u a l a i r s p e e d would have been 100
knots. 17/
I n a s m u c h a s a n a c t u a l s p e e d of 100 knots is v e r y c l o s e to t h e s t a l l i n g
s p e e d of t h e a i r c r a f t i n t h e landing configuration, it i s highly unlikely t h a t
s u c h a condition would e s c a p e t h e n o t i c e of t h e pilots. It is t h e r e f o r e signific a n t t h a t no mention of any s u c h p r o b l e m w a s m a d e during t h e a p p r o a c h .
The a c c u r a c y of t h e a i r s p e e d i n s t r u m e n t s i s f u r t h e r v e r i f i e d by t h e t i m e
taken to fly f r o m t h e o u t e r m a r k e r to the point of i m p a c t . In view of t h e
above, t h e B o a r d c o n c l u d e s t h a t both t h e i n d i c a t e d and a c t u a l a i r s p e e d s w e r e
i n t h e a r e a of 130 knots during t h e a p p r o a c h .
-
The only explanation which would r e c o n c i l e an i n a c c u r a t e b a r o m e t r i c
a l t i m e t e r with a n a c c u r a t e a i r s p e e d i n d i c a t o r i s t h a t t h e r e was a n e r r o r i n
t h e Pitot s y s t e m which roughly o f f s e t t h e e r r o r i n t h e s t a t i c s y s t e m . The
B o a r d , however, is not a w a r e of any phenomenon, a t m o s p h e r i c o r o t h e r w i s e ,
which could p r o d u c e s u c h a n offsetting e r r o r , n o r w a s t h e r e any eviddnce
t h e r e o f u n c o v e r e d during t h i s investigation. In t h i s connection; it should be
n o t e d t h a t l o n g - t e r m r e s e a r c h is underway to d e t e r m i n e w h e t h e r flight and
w e a t h e r condition's c a n l e a d to m i s i n f o r m a t i o n f r o m i n s t r u m e n t s connected
[ F o o t n o t e continued] a p p r o a c h a t 130 knots, a n d t h e f i r s t o f f i c e r ' s c a l l o u t s
w e r e within t 7 knots of t h a t f i g u r e . T h i s a p p r o x i m a t e value w a s a l s o
r e c o r d e d b y h e a i r s p e e d t r a c e o n t h e flight data r e c o r d e r .
16/
QNH i s t h e a l t i t u d e above s e a l e v e l b a s e d o n s t a t i o n b a r o m e t r i c
p r e s s u r e.
17/
The above c a l c u l a t i o n s a r e set f o r t h i n d e t a i l i n Appendix E. A s
f u r t h e r c a l c u l a t e d i n t h a t appendix, a s t a t i c s y s t e m e r r o r which would
c a u s e a 200-foot a l t i m e t e r e r r o r would p r o d u c e a c o r r e s p o n d i n g a i r s p e e d e r r o r of -17. 5 k n o t s (i. e . , when t h e a i r s p e e d i n d i c a t o r r e a d
130 knots, t h e a c t u a l a i r s p e e d w o u l d b e 112. 5 knots).
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28
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to t h e s t a t i c s y s t e m . But until this o r o t h e r e f f o r t s p r o d u c e positive evidence
of a phenomenon which could c a u s e offsetting e r r o r s of the type d i s c u s s e d
above, the B o a r d cannot conclude that a s t a t i c s y s t e m e r r o r is s u p p o r t e d by
sufficient evidence to b e t e r m e d a c a u s a l f a c t o r i n t h i s accident.
The s e c o n d r e a s o n a b l y p o s s i b l e explanation f o r t h e u n r e c o g n i z e d
d e s c e n t below MDA i s t h a t t h e first o f f i c e r w a s using the r a d i o a l t i m e t e r a s
t h e p r i m a r y s o u r c e of a l t i t u d e r e f e r e n c e , and t h e c r e w w a s t h e r e b y m i s l e d
into believing t h e a i r c r a f t w a s higher than it actually w a s b e c a u s e the ground
s u r f a c e i n the a p p r o a c h a r e a i s a t s o m e points s u b s t a n t i a l l y l o w e r than t h e
1 8 / Support f o r t h i s t h e o r y c a n b e d e r i v e d f r o m a n a n a l y s i s
f i e l d elevation. of t h e altitude c a l l o u t s on the cockpit voice r e c o r d e r . T h e r e w e r e a t l e a s t
four r e f e r e n c e s to altitude a f t e r t h e flight p a s s e d t h e o u t e r m a r k e r inbound.
Since t h e c r e w had no way of d e t e r m i n i n g t h e elevation of the t e r r a i n below
t h e m , t h e v a l u e s could have been e i t h e r r e a d d i r e c t l y f r o m the r a d i o a l t i m e ter o r c a l c u l a t e d mentally by s u b t r a c t i n g t h e field elevation f r o m the
b a r o m e t r i c a l t i m e t e r reading. The following tabulation shows (1) the first
o f f i c e r ' s callout, (2) the flight r e c o r d e r indication, (3) t h e t e r r a i n elevation
a t t h a t point, ( 4 ) the c a l c u l a t e d r a d i o a l t i m e t e r reading, b a s e d o n the flight
r e c o r d e r altitude m i n u s the t e r r a i n elevation, and ( 5 ) t h e flight r e c o r d e r
altitude r e a d i n g m i n u s t h e f i e l d elevation (828 f e e t ) .
Flight
Reco r d e r
(m.s.1.)
Terrain
(m.s.1.)
C a l c ula t e d
Radio
Altimeter
(m.s.1.)
1,000 feet
1,842 feet
600 f e e t
1, 242 f e e t
ay, ah, 700
1,330
500
780
502
200 above
(612 feet)
1,224
530
694
396
400 f e e t
1,005
690
315
177
C allou t
(a. g. 1. )
Calculated
B a r o m e t r i c minus
F i e l d Elevation
(a. g. 1. )
* I
1,014 feet
,
Any r e l i a n c e o n t h e s e f i g u r e s m u s t include recognition of t h e i r limit a t i o n s . The computed flightpath of t h e a i r c r a f t m a y b e affected by s u c h
18/
The r a d i o a l t i m e t e r , unlike the b a r o m e t r i c a l t i m e t e r , i n d i c a t e s the
height of the a i r c r a f t above t h e t e r r a i n o v e r which t h e plane i s
flying.
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29
-
v a r i a b l e s a s winds a l o f t a n d flight r e c o r d e r a c c u r a c y . Any l a t e r a l a d j u s t m e n t to t h e flightpath m a y change t h e height of t h e a i r c r a f t above t h e hilly
t e r r a i n . The t i m e c o r r e l a t i o n between t h e flight r e c o r d e r and cockpit voice
r e c o r d e r m a y not b e e x a c t and could a l t e r t h e a n a l y s i s . The individual
d e l a y , anticipation, o r a p p r o x i m a t i o n i n e a c h of t h e c a l l o u t s could have s o m e
b e a r i n g on t h e tabulation. Finally, t h e r e is no way of d e t e r m i n i n g w h e t h e r
t h o s e v a r i a b l e s which could be involved would o f f s e t e a c h o t h e r o r would b e
c u m u l a t i v e . However, with r e s p e c t to t h e t o l e r a n c e s , t h e a i r c r a f t w a s
a p p a r e n t l y flying p a r a l l e l to a 6OO-foot contour l i n e a t t h e t i m e of t h e 1,000foot callout, and t h e flightpath would have to b e s h i f t e d a p p r o x i m a t e l y 350
f e e t h o r i z o n t a l l y b e f o r e a d i f f e r e n c e of 100 f e e t i n t h e t e r r a i n c l e a r a n c e
would be i n d i c a t e d o n a r a d i o a l t i m e t e r . The s e c o n d and t h i r d c a l l o u t s
o c c u r r e d when t h e flight w a s n e a r t h e f l a t t e r r a i n of t h e r i v e r b e d a n d t h e
flightpath would have to b e s h i f t e d a p p r o x i m a t e l y 700 f e e t h o r i z o n t a l l y b e f o r e
t h e t e r r a i n c l e a r a n c e would a p p e a r to change 100 feet. When t h e final c a l l o u t was m a d e , t h e flight w a s c r o s s i n g p e r p e n d i c u l a r l y t o a s t e e p r i d g e which
r i s e s s h a r p l y to a n elevation of a p p r o x i m a t e l y 700 f e e t o n t h e e a s t bank of t h e
r i v e r . The flightpath m u s t be s h i f t e d a t l e a s t 400 f e e t h o r i z o n t a l l y b e f o r e
a change of 100 f e e t would b e i n d i c a t e d i n t h e t e r r a i n c l e a r a n c e . 1 9 /
-
A n a l y s i s of t h e t a b u l a t i o n s u g g e s t s t h a t a l l but t h e i n i t i a l c a l l o u t of
I t could h a v e been m a d e w i t h r e f e r "A thousand f e e t above t h e g r o u n d .
e n c e to t h e r a d i o a l t i m e t e r , but even it w a s couched i n t e r m s g e n e r a l l y
a s s o c i a t e d with t h e r a d i o a l t i m e t e r . The r e a d i n g s t h a t would d e r i v e f r o m
s u b t r a c t i n g t h e f i e l d elevation f r o m t h e b a r o m e t r i c a l t i m e t e r r e a d i n g a r e
c o n s i s t e n t l y about 200 f e e t low, and a s s u m i n g t h a t t h e b a r o m e t r i c a l t i m e t e r
w a s a c c u r a t e , the first o f f i c e r would have been r e p o r t i n g d i f f e r e n t v a l u e s i f
he h a d been u s i n g t h a t method. On t h e o t h e r hand, t h e a l t i t u d e v a l u e s d e r i v e d by r e f e r e n c e to t h e r a d i o a l t i m e t e r a r e all within 100 feet of t h e a l t i t u d e s r e p o r t e d by t h e first o f f i c e r . M o r e o v e r , t h e final e x c l a m a t i o n r e c o r d e d p r i o r to t h e c o m m e n c e m e n t of t h e sound of i m p a c t ("HUNDRED")
a c c o r d s with t h e a l t i t u d e which would have been r e f l e c t e d by t h e r a d i o a l t i m e t e r a t t h a t t i m e and t h e r e f o r e i s f u r t h e r evidence t h a t t h e first o f f i c e r m a y
have b e e n using t h a t i n s t r u m e n t during the a p p r o a c h . 201
..
S o u t h e r n ' s t r a i n i n g p r o g r a m d i s t i n g u i s h e d between t h e u s e of r a d i o
19/
It is not p o s s i b l e to d e t e r m i n e a c c u r a t e l y t h e a i r c r a f t position l o n g i tudinally on t h e flightpath when a r a d i o a l t i m e t e r r e a d i n g m i g h t have
been m a d e t h a t r e s u l t e d i n a n a l t i t u d e c a l l .
20/
It i s a l s o p o s s i b l e t h a t t h e w o r d "HUNDRED" w a s not a r e f e r e n c e to
altitude, but r a t h e r w a s t h e first p a r t of a n a i r s p e e d callout.
-
30
-
a l t i m e t e r s i n i n s t r u m e n t a p p r o a c h e s o v e r l e v e l a n d i r r e g u l a r t e r r a i n . Howe v e r , t h e Southern A i r w a y s DC-9 Operating Manual did not m a k e s u c h a
distinction, but r a t h e r a c c e n t u a t e d its u s e f o r all i n s t r u m e n t a p p r o a c h e s by
a r e provided to
s t a t i n g that, "Two s e p a r a t e r a d i o a l t i m e t e r s y s t e m s
obtain p r e c i s e altitude i n f o r m a t i o n above the g r o u n d a t t h e m i n i m u m decision [ s i c ] altitude (MDA). This i n f o r m a t i o n i s e s s e n t i a l to t h e pilot i n his
d e c i s i o n to l a n d o r i n i t i a t e a g o - a r o u n d m a n e u v e r . I ' Notwithstanding t h e f a c t
t h a t the c r e w m a y have been f o r m a l l y t r a i n e d to u s e the r a d i o a l t i m e t e r a s a
s e c o n d a r y f e f e r e n c e , the tabulation c o m p a r i n g the a v a i l a b l e altitude r e f e r e n c e s indicated t h a t the first o f f i c e r m a y have r e l i e d on t h e w r i t t e n m a t e r i a l
and w a s using the r a d i o a l t i m e t e r f o r altitude information.
...
If the first o f f i c e r w a s making a l t i t u d e c a l l o u t s by r e f e r e n c e to the
r a d i o a l t i m e t e r , a s hypothesized above, t h e r e m a i n i n g question c o n c e r n s
the extent to which t h e captain r e l i e d upon, and w a s m i s l e d by, s u c h callouts.
Sound o p e r a t i n g p r o c e d u r e s dictate t h a t the c a p t a i n should have been using
h i s b a r o m e t r i c a l t i m e t e r d u r i n g t h e approach, a n d t h e r e f o r e should have been
a w a r e of t h e d i s p a r i t i e s between a l t i t u d e s r e f l e c t e d by t h a t i n s t r u m e n t and
t h e first o f f i c e r ' s callouts. Why t h e s e d i s p a r i t i e s w e r e a p p a r e n t l y not det e c t e d by t h e c a p t a i n i s difficult to explain. It i s p o s s i b l e t h a t he, l i k e the
first o f f i c e r , w a s relying on h i s r a d i o a l t i m e t e r . A s e c o n d possibility i s
t h a t he w a s not using h i s b a r o m e t r i c o r r a d i o a l t i m e t e r , but r a t h e r was r e lying solely on t h e first o f f i c e r f o r altitude information. Finally, he may
have been including h i s b a r o m e t r i c a l t i m e t e r i n h i s i n s t r u m e n t s c a n , but
w a s c o n c e r n e d with o t h e r items during the final s t a g e s of the a p p r o a c h to
s u c h a n extent t h a t he did not notice any v a r i a t i o n s .
On t h e o t h e r hand, t h e r e a r e s e v e r a l w e a k n e s s e s to t h e t h e o r y t h a t the.
r a d i o altimeter w a s being u s e d f o r altitude information. First, and p e r h a p s
rrrost i m p o r t a n t , t h e r a d i o a l t i m e t e r is not intended f o r u s e during an a p p r o a c h
o v e r unknown o r uneven t e r r a i n , and i t i s t h e r e f o r e difficult to a c c e p t t h a t
qualified, e x p e r i e n c e d pilots would r e s o r t to t h a t i n s t r u m e n t i n conducting
the a p p r o a c h a t Huntington. The t h e o r y a l s o a s s u m e s a n unlikely dual human
f a i l u r e i n t h a t t h e c a p t a i n was e i t h e r a l s o using h i s r a d i o a l t i m e t e r o r did
not r e c o g n i z e t h e d i f f e r e n c e s between t h e b a r o m e t r i c a l t i m e t e r a n d the
altitude i n f o r m a t i o n c a l l e d by t h e first o f f i c e r a n d was relying on t h e l a t t e r .
Finally, t h e r a t e s of d e s c e n t between t h e c a l l s of "Seven hundred feet, I f
"Two h u n d r e d above, I' "Four hundred, I' and rotation, i f m a d e f r o m refere n c e to t h e r a d i o altimeter, do not c o r r e s p o n d to t h e r a t e s of d e s c e n t r e c o r d e d by the flight d a t a r e c o r d e r f o r t h e s a m e p e r i o d s .
This v a r i a t i o n i s d e m o n s t r a t e d i n the following calculations. By using
t h e t e r r a i n elevation e s t a b l i s h e d by t h e flightpath a n a l y s i s f o r the position
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of the a i r c r a f t at the t i m e t h e r e f e r e n c e c a l l s w e r e made, and adding t h e s e
c a l l s to that elevation, the following tabulation shows (1) t h e first o f f i c e r ' s
callout, ( 2 ) the flight r e c o r d e r indication, (3) t e r r a i n elevation, and ( 4 )
t h e altitude, i f a radio a l t i m e t e r was being u s e d ( t e r r a i n plus the callout).
Flight
Recorder
Terrain
Elevation
Terrain
P l u s Callout
700 f e e t
1,330
550
1,250
200 above
1,224
530
1,130
400
1,005
690
1,090
925
89 1
C allou t
Rotation p r i o r
to tree i m p a c t
B a s e d on the above points, t h e following rates of d e s c e n t would be r e q u i r e d :
R a t e s of Descent ( f e e t / m i n u t e )
F l i g h t Data
Terrain
Recorder
P l u s Callouts
Between C a l l s
"700 f e e t " to "200 Above"
(5. 2 s e c o n d s )
1,155
1,386
"200 Above" to "400"
( 9 . 4 seconds)
1,184
1,053
"400" to point of rotation
( 2 seconds)-2 1 /
1,286
2,789
It is noted t h a t t h e rates of d e s c e n t c a l c u l a t e d f o r the flight r e c o r d e r
data a r e i n a n i n c r e a s i n g p a t t e r n a n d r e l a t i v e l y c l o s e to t h e o v e r a l l r a t e
d e s c r i b e d by the flight r e c o r d e r . The r a t e s of d e s c e n t b a s e d o n the c a l c u l a t e d r a d i o a l t i m e t e r c a l l o u t s show c l o s e c o r r e l a t i o n f o r the i n i t i a l two c a l l o u t s , but i n t h e final s e g m e n t the descent r a t e i s a p p r o x i m a t e l y double the
overall rate.
After c a r e f u l l y weighing t h e conflicting points s e t f o r t h above, the
B o a r d concludes t h a t t h e t h e o r y under c o n s i d e r a t i o n
namely, t h a t t h e
unrecognized d e s c e n t through MDA w a s the r e s u l t of using the r a d i o a l t i m e t e r
--
21/
Analysis of a i r c r a f t p e r f o r m a n c e data, the flight data r e c o r d e r , and
t h e cockpit c o n v e r s a t i o n l e a d s to the conclusion t h a t the a i r c r a f t was
r o t a t e d approximately 2 s e c o n d s a f t e r the callout of 400 feet.
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32
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f o r altitude r e f e r e n c e - - ispnot s u p p o r t e d by sufficient evidence to be t e r m e d
a c a u s a l f a c t o r i n t h i s accident.
One final m a t t e r , a i r p o r t f a c i l i t i e s , w a r r a n t s comment. Many of the
c i r c u m s t a n c e s of t h i s a c c i d e n t a r e typical o f the approach/landing a c c i d e n t s
t h a t o c c u r during n o n p r e c i s i o n a p p r o a c h e s . A s a r e s u l t , t h e B o a r d exa m i n e d the environmental conditions t h a t e x i s t e d i n t h i s c a s e to d e t e r m i n e
what a i d s would have a s s i s t e d t h e pilot i n making a n o n p r e c i s i o n approach.
The t e r r a i n under t h e a p p r o a c h path w a s i r r e g u l a r with n u m e r o u s hills
of varying heights. T h e r e w e r e few l i g h t s along the a p p r o a c h p a t h excepting
t h o s e of the r e f i n e r y which w e r e to the right of the inbound t r a c k . The l o w e r
clouds w e r e r a g g e d and t h e r e s t r i c t i o n s to visibility included d a r k n e s s , r a i n ,
fog, and smoke. The pilot h a d h i s b a r o m e t r i c a l t i m e t e r , v e r t i c a l s p e e d
i n d i c a t o r , a i r s p e e d i n d i c a t o r , and r a d i o a l t i m e t e r to a i d him i n establishing
the d e s i r e d d e s c e n t profile. However, t h e pilot had l i t t l e , i f any, i n f o r m a tion i n s t a n t l y a v a i l a b l e to h i m r e g a r d i n g t h e elevation and c h a r a c t e r of the
t e r r a i n below the a i r c r a f t o r the flightpath r e l a t e d t h e r e t o .
E x t e r n a l navigational a i d s u s e d to provide v e r t i c a l guidance to a
pilot during a n i n s t r u m e n t a p p r o a c h include P r e c i s i o n Approach R a d a r
( P A R ) , ILS glide slope, and VASI s y s t e m . T h e r e w a s no PAR i n s t a l l e d a t
Huntington n o r w a s the i n s t a l l a t i o n of one under consideration. The FAA
policy w a s to p r o v i d e VASI s y s t e m s p r i m a r i l y w h e r e no o t h e r e l e c t r o n i c
guidance w a s e i t h e r planned o r available. Since Huntington had been actively
negotiating f o r a glide s l o p e s i n c e 1957 no VASI s y s t e m w a s i n s t a l l e d . In
t h i s c a s e , t h e VASI s y s t e m would have been useful i f the pilot h a d been a b l e
to s e e t h e first 1, 500 f e e t of the runway. However, i f t h e pilot had not
visually a c q u i r e d contact with that m u c h of the runway he would not have been
a b l e to u s e t h e VASI s y s t e m f o r v e r t i c a l guidance.
It i s a l s o p o s s i b l e t h a t the n o n s t a n d a r d glide slope which w a s i n s t a l l e d
s u b s e q u e n t to t h e a c c i d e n t m i g h t have p r e v e n t e d t h i s a c c i d e n t i n t h a t the
pilot would have been provided with a p r i m a r y e l e c t r o n i c indication of his
position r e l a t i v e to the d e s i r e d glide path. This c r o s s - c h e c k a g a i n s t t h e
a l t i m e t e r i n f o r m a t i o n a v a i l a b l e would have a l e r t e d t h e c r e w to any d i s c r e p ancy between t h e intended and a c t u a l descent. Additionally, i f t h e a i r c r a f t
r e m a i n e d on t h e glide slope, it would have a r r i v e d at t h e MDA a p p r o x i m a t e l y
2 , 5 0 0 f e e t c l o s e r to t h e hill w h e r e i n i t i a l i m p a c t o c c u r r e d , and it would have
had to d e s c e n d a t an unusually s t e e p angle of about 10' to s t r i k e the t r e e s
f r o m t h a t point.
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-
In view of t h e a p p a r e n t s u c c e s s of t h e n o n s t a n d a r d glide s l o p e a t
Huntington, it i s unfortunate t h a t s u c h a n i n s t a l l a t i o n w a s not m a d e s o o n e r .
However, t h e e x p e r i e n c e gained with t h i s i n s t a l l a t i o n should p r o v i d e a b a s i s
f o r p o s s i b l e application to o t h e r a i r p o r t s w h e r e s t a n d a r d i n s t a l l a t i o n c r i t e r i a c a n n o t be m e t without m a j o r c o n s t r u c t i o n .
2. 2
Conclusions
( a ) Findings
The pilots w e r e p r o p e r l y c e r t i f i c a t e d and qualified to
conduct t h i s flight.
The a i r c r a f t w a s c e r t i f i c a t e d a n d m a i n t a i n e d i n a c c o r d a n c e
with t h e existing FAA r u l e s and company p r o c e d u r e s , and
was p r o p e r l y equipped f o r t h e intended flight.
The flight w a s conducted i n a c c o r d a n c e with t h e p r o v i s i o n s
of FAR 121.445 and with company p r o c e d u r e s a p p l i c a b l e
to "off r o u t e " c h a r t e r flights.
The c h a r t e r a r r a n g e m e n t s between S o u t h e r n A i r w a y s , Inc.
and M a r s h a l l U n i v e r s i t y w e r e a d j u s t e d and t h e a i r c r a f t
w a s l o a d e d within t h e o p e r a t i o n a l capability of t h e a i r c r a f t .
The c a r r i e r u s e d the s a m e a i r c r a f t , p i l o t s , d i s p a t c h e s ,
flight planning s e r v i c e s , and s u p e r v i s i n g p e r s o n n e l i n t h i s
o p e r a t i o n a s they u s e d i n t h e i r r e g u l a r l y s c h e d u l e d s e r v i c e .
The flight r e l e a s e to t h e Huntington a i r p o r t a n t i c i p a t e d t h a t
t h e runway would b e wet, and w a s p r e d i c a t e d o n t h e a v a i l ability of sufficient runway a s r e q u i r e d by FAR 121. 195(b).
T h e a i r c r a f t weight a n d c e n t e r of g r a v i t y w e r e within l i m i t s
f o r t h e i n t e n d e d landing a t Huntington.
The runway l e n g t h at t h e Huntington a i r p o r t w a s a d e q u a t e
f o r t h e intended landing, u n d e r t h e e x i s t i n g c i r c u m s t a n c e s .
The i n s t r u m e n t a p p r o a c h a i d s a t Huntington, which p r o v i d e d
l a t e r a l but not v e r t i c a l guidance to t h e runway, w e r e o p e r a t i n g
p r o p e r l y a t t h e t i m e of t h e a c c i d e n t .
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34
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( 1 0 ) The a i r p o r t lighting s y s t e m , which included high intensity
a p p r o a c h l i g h t s , sequence f l a s h e r s , a n d high intensity
runway l i g k t s , w a s i n o p e r a t i o n and p r o p e r l y set at t h e
t i m e of the accident.
(11) The m i n i m a f o r t h i s a p p r o a c h ( m i n i m u m d e s c e n t altitude of
1, 240 f e e t m. s . 1. and m i n i m u m visibility of 1 m i l e ) w e r e
the same a s t h o s e p r e s c r i b e d f o r any nonscheduled flight
into Huntington. T h e s e m i n i m a w e r e adequate f o r the
intended operation.
(12)
The w e a t h e r r e p o r t e d a t the field at t h e t i m e of t h e a c c i d e n t
was 300 f e e t s c a t t e r e d , m e a s u r e d 500 f e e t v a r i a b l e broken
ceiling, 1100 f e e t o v e r c a s t , visibility 5 m i l e s i n light r a i n ,
fog, and s m o k e ; however, t h e w e a t h e r i n t h e a p p r o a c h a r e a
was wo r s e.
(13) The investigation d i s c l o s e d no malfunction o r f a i l u r e i n the
a i r c r a f t s t r u c t u r e , p r i m a r y flight c o n t r o l s , o r powerplants.
(14) T h e r e w a s no physical evidence of a defect o r contamination
in the s t a t i c s y s t e m tubing o r p a r t s ; a s t a t i c s y s t e m e r r o r is
e x t r e m e l y unlikely u n l e s s t h e r e w a s a n offsetting e r r o r i n
the pitot s y s t e m .
( 1 5 ) The captain w a s using t h e autopilot throughout the a p p r o a c h
a n d t h e r e was no evidence of a significant autopilot malfunction.
(16) Based on the r e c o r d e d cockpit c o n v e r s a t i o n , the c r e w w a s
familiar with t h e a p p r o a c h p r o c e d u r e s a t Huntington and
with the MDA on the a p p r o a c h being flown.
(17) The c r e w deviated f r o m t h e o p t i m a l a p p r o a c h p r o c e d u r e s i n
s e v e r a l r e s p e c t s ; however, t h e effect of t h i s deviation on the
a c c i d e n t cannot be a s s e s s e d i n a s m u c h a s the cockpit c o n v e r s a t i o n i n d i c a t e d the c r e w had altitude a w a r e n e s s .
(18)
The flight descended through t h e MDA of 1 , 2 4 0 f e e t m. s.1.
a p p r o x i m a t e l y 2 miles f r o m the end of the runway and the
d e s c e n t continued f o r o v e r 300 f e e t b e f o r e the c r e w i n i t i a t e d
a m i s s e d a p p r o a c h o r go-around.
The copilot's c a l l of "Four hundred" is c o n s t r u e d to m e a n
t h a t an a l t i m e t e r i n d i c a t e d that the a i r c r a f t w a s at t h e MDA.
The c r e w 'was u n a w a r e that the a i r c r a f t had descended
through t h e a c t u a l MDA.
The c r e w sighted the glow f r o m the r e f i n e r y l i g h t s during
the approach, but n e v e r obtained v i s u a l contact with any
p a r t of the runway environment.
The probable r e a s o n for t h e unrecognized d e s c e n t through
MDA cannot be d e t e r m i n e d ; the two m o s t likely explanations
a r e ( a ) an e r r o r i n t h e s t a t i c s y s t e m which c a u s e d t h e
b a r o m e t r i c a l t i m e t e r s to i n d i c a t e a f i g u r e higher than the
a c t u a l altitude, o r ( b ) r e l i a n c e by the c r e w o n t h e radio
a l t i m e t e r as a p r i m a r y altitude r e f e r e n c e while executing
a n a p p r o a c h o v e r uneven t e r r a i n .
The accident might have been p r e v e n t e d i f t h e r e had been
available t h e nonstandard glide s l o p e which was i n s t a l l e d
at a l a t e r date.
(b) P r o b a b l e C a u s e
The National T r a n s p o r t a t i o n Safety B o a r d d e t e r m i n e s t h a t the
p r o b a b l e c a u s e of t h i s a c c i d e n t w a s t h e d e s c e n t below M i n i m u m Descent
Altitude during a nonprecision a p p r o a c h u n d e r a d v e r s e o p e r a t i n g conditions,
without v i s u a l contact with the runway environment. The B o a r d
h a s been unable to d e t e r m i n e t h e r e a s o n f o r t h i s descent,although the two
m o s t likely explanations a r e ( a ) i m p r o p e r u s e of cockpit i n s t r u m e n t a t i o n
data, o r (b) a n a l t i m e t r y s y s t e m e r r o r .
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36
-
3.
RECOMMENDATIONS
Although the Safety Board h a s been unable to d e t e r m i n e the p r o b a b l e
r e a s o n f o r the unrecognized d e s c e n t below MDA in this i n s t a n c e , the Board
w i s h e s t o r e i t e r a t e i t s c o n c e r n with the g e n e r a l p r o b l e m of landing and a p p r o a c h a c c i d e n t s and to r e e m p h a s i z e i t s i n t e r e s t i n the v a r i o u s p r e v e n t i v e
m e a s u r e s which might p r o v e u s e f u l i n reducing the r a t e of t h e s e kinds of
a c c i d e n t s . T h e r e is a need f o r a l l s e g m e n t s of the a v i a t i o n i n d u s t r y to
continue to focus attention on the unique d e m a n d s f o r c r e w c o o r d i n a t i o n
and vigilance during n o n p r e c i s i o n a p p r o a c h e s . A r e a navigation s y s t e m s ,
now in the f i n a l proving s t a g e s of d e v e l o p m e n t , will a p p a r e n t l y p r o v i d e
d e s c e n t guidance c a p a b i l i t y within the a i r c r a f t and should be s t a n d a r d
equipment on a l l f u t u r e t r a n s p o r t c a t e g o r y a i r c r a f t . The r e t r o f i t t i n g of
a i r c r a f t i n the i n v e n t o r y should be expedited a s m u c h a s p o s s i b l e .
The Safety B o a r d a l s o notes and s u p p o r t s the FAA i n i t s i s s u a n c e of
A i r C a r r i e r Operations Bulletin No. 71-9 which e m p h a s i z e s the c o m m o n
f a u l t s noted in n o n p r e c i s i o n a p p r o a c h e s and p r o p o s e s s e v e r a l r e c o m m e n d a tions to e l i m i n a t e t h e s e f a u l t s . (See Appendix F. )
In view of the foregoing, the Safety Board r e c o m m e n d s that:
1. All s e g m e n t s of the aviation i n d u s t r y continue to f o c u s
attention on the unique d e m a n d s f o r c r e w c o o r d i n a t i o n
and vigilance d u r i n g n o n p r e c i s i o n a p p r o a c h e s . P a r t i c u l a r e m p h a s i s should be p l a c e d on the a c c e l e r a t e d developm e n t of a r e a navigation s y s t e m s with v e r t i c a l guidance
c a p a b i l i t y and on h e a d s -up d i s p l a y s y s t e m s .
The B o a r d , on F e b r u a r y 13, 1968, s u p p o r t e d a Notice of P r o p o s e d Rule
Making which would r e q u i r e the i n s t a l l a t i o n of an altitude warning d e v i c e f o r
t u r b o j e t powered c i v i l a i r p l a n e s . The b a s i s f o r t h i s s u p p o r t , c i t e d in the
l e t t e r , was a s e r i e s of a i r c r a f t a c c i d e n t s involving a i r c a r r i e r a i r c r a f t that
had b e e n involved i n c o n t r o l l e d c r a s h e s into the ground d r w a t e r , Of the five
a c c i d e n t s c i t e d , t h r e e o c c u r r e d d u r i n g the f i n a l a p p r o a c h to landing. In the
o t h e r two c a s e s , the a i r c r a f t w e r e descending i n p r e p a r a t i o n f o r an a p p r o a c h
and landing.
On J a n u a r y 17, 1969, writing with r e f e r e n c e to a c c i d e n t s which o c c u r d u r i n g
the a p p r o a c h and landing p h a s e of flight, the B o a r d r e c o m m e n d e d , among o t h e r
things, the development and i n s t a l l a t i o n of audible and v i s u a l a l t i t u d e warning
d e v i c e s and the i m p l e m e n t a t i o n of p r o c e d u r e s f o r the u s e of s u c h d e v i c e s . The
FAA r e s p o n s e to t h i s r e c o m m e n d a t i o n w a s to c i t e i t s r u l e making dated Sept e m b e r 1968, which r e q u i r e d the i n s t a l l a t i o n of altitude a l e r t i n g d e v i c e s i n all
t u r b o powered c i v i l a i r c r a f t . T h i s d e v i c e would p r o v i d e both a u r a l and v i s u a l
indications to w a r n p i l o t s when they a p p r o a c h s e l e c t e d a l t i t u d e s d u r i n g c l i m b s ,
-
37
-
d e s c e n t s , and i n s t r u m e n t a p p r o a c h e s . However, the B o a r d h a s found t h a t
t h i s d e v i c e as i n s t a l l e d and o p e r a t e d d o e s not p r o v i d e a n y i n f o r m a t i o n r e g a r d ing the a i r c r a f t p r o x i m i t y t o the ground d u r i n g the f i n a l a p p r o a c h p h a s e of a
landing a p p r o a c h .
On November 10, 1971, in a n a i r c r a f t a c c i d e n t r e p o r t , NTSB-AAR-71-14,
the B o a r d r e c o m m e n d e d t h a t a ground p r o x i m i t y warning d e v i c e be developed
f o r u s e d u r i n g the a p p r o a c h and landing p h a s e of flight. T h e B o a r d f u r t h e r
r e c o m m e n d e d t h a t a p p r o p r i a t e o p e r a t i n g p r o c e d u r e s be developed and i m p l e mented.
The A d m i n i s t r a t o r ' s r e s p o n s e t o t h i s r e c o m m e n d a t i o n s t a t e d i n p a r t :
I t
. . . With r e s p e c t to t h e r e c o m m e n d a t i o n t o develop a ground p r o x i m i t y
warning s y s t e m f o r u s e d u r i n g a p p r o a c h and landing, we b e l i e v e t h e p r e s e n t
i n s t r u m e n t s and p r o c e d u r e s a r e s a f e and adequate. T h i s p r e s u p p o s e s that
p r o p e r cockpit d i s c i p l i n e s a r e maintained
We a r e , h o w e v e r , r e a s s e s s ing our s y s t e m r e q u i r e m e n t s f o r n o n p r e c i s i o n s t r a i g h t - i n a p p r o a c h s y s t e m s
with a view to providing additional a s s i s t a n c e to the pilot in the f o r m of a c c u r a t e p o s i t i o n i n f o r m a t i o n which w i l l m a k e his evaluation of the v i s u a l a p .'I
(See Appendix G . )
p r o a c h s e g m e n t l e s s s u s c e p t i b l e to h u m a n e r r o r
...
..
F i n a l l y , on F e b r u a r y 25, 1972, B o a r d R e p o r t NTSB-AAR-72-4 contained
a r e c o m m e n d a t i o n t h a t the A d m i n i s t r a t o r r e q u i r e all air c a r r i e r a i r c r a f t t o
be equipped with a functional ground p r o x i m i t y warning d e v i c e i n addition to
t h e b a r o m e t r i c a l t i m e t e r s . The A d m i n i s t r a t o r ' s r e s p o n s e continued t o s u p p o r t the e a r l i e r p o s i t i o n quoted above. (See Appendix G. ) In addition, the
F A A a d v i s e d the B o a r d that they w e r e developing new c r i t e r i a which they
p r o p o s e d t o apply t o n o n p r e c i s i o n a p p r o a c h e s . One c r i t e r i o n involves e s t a b l i s h i n g a f i n a l a p p r o a c h d e s c e n t fix. T h i s f i x would b e l o c a t e d a t a point on
the f i n a l a p p r o a c h f r o m which a n o r m a l d e s c e n t p a t h of a p p r o x i m a t e l y 3 O f r o m
MDA to touchdown could be c o m m e n c e d , provided the r e q u i r e d v i s u a l r e f e r e n c e
w a s e s t a b l i s h e d . P i l o t s would b e r e q u i r e d t o m a i n t a i n a n a l t i t u d e a t or above
the MDA until p a s s i n g t h i s d e s c e n t fix. Another c r i t e r i o n the FAA p r o p o s e d
w i l l be t o p r o v i d e VASI f o r e a c h runway s e r v e d b y a n o n p r e c i s i o n a p p r o a c h .
T h e VASI w i l l p r o v i d e v e r t i c a l guidance a t n o r m a l d e s c e n t r a t e s f o r the v i s u a l
s e g m e n t of the a p p r o a c h .
The B o a r d b e l i e v e s that t h e s e two i t e m s will aid i n p r e v e n t i n g a c c i d e n t s
that o c c u r d u r i n g n o n p r e c i s i o n a p p r o a c h e s and b e l i e v e s t h a t t h e s e p r o p o s a l s
a r e t i m e l y and a p p r o p r i a t e . The B o a r d a l s o u r g e s the FAA, w h e r e v e r p h y s i c a l l y p o s s i b l e and within the l i m i t s of a v a i l a b l e r e s o u r c e s , t o convert a p p r o a c h e s f r o m n o n p r e c i s i o n to p r e c i s i o n a t qualified a i r p o r t s t h r o u g h the
i n s t a l l a t i o n of a n ILS. In this connection, even the i n s t a l l a t i o n of a nons t a n d a r d glide s l o p e , s u c h as the one c u r r e n t l y i n u s e a t Huntington, i s a
s u b s t a n t i a l i m p r o v e m e n t in the a i d s a v a i l a b l e to a pilot in making h i s a p p r o a c h
descent.
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38
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With r e g a r d to the A d m i n i s t r a t o r ' s r e s p o n s e to our r e c o m m e n d a t i o n
t h a t he r e e v a l u a t e h i s position r e g a r d i n g the i n s t a l l a t i o n and u s e of ground
p r o x i m i t y warning devices, the Board notes that the d e c i s i o n i s b a s e d on
the a s s u m p t i o n that " p r o p e r cockpit d i s c i p l i n e s a r e maintained. I t We have
found in s e v e r a l c a s e s of t h i s type that cockpit d i s c i p l i n e s w e r e d i s r u p t e d
by unusual actions o r events and the c r e w was d i s t r a c t e d f r o m its t a s k of
monitoring the a i r c r a f t altitude. We b e l i e v e that a ground p r o x i m i t y w a r n ing d e v i c e would s e r v e to b r i n g the c r e w ' s attention b a c k t o the a l t i m e t e r s
a s the a i r c r a f t approached p r e s e l e c t e d a l t i t u d e s d u r i n g a n i n s t r u m e n t app r o a c h . T h e r e f o r e , the Board again r e c o m m e n d s that:
2.
The A d m i n i s t r a t o r evaluate the need f o r the i n s t a l l a t i o n and
u s e of ground p r o x i m i t y warning d e v i c e s on air c a r r i e r a i r c r a f t .
After c o n s i d e r a t i o n of the a i r p o r t qualifications e s t a b l i s h e d by FAR
121.443 and 121.445, the Board concludes that the r e q u i r e m e n t s of 12.445
a r e l e s s specific than those i n 121.443. The Board b e l i e v e s that P a r t
121.445, o r the c a r r i e r p r o c e d u r e s p r o m u l g a t e d t h e r e u n d e r , could be m o r e
s p e c i f i c , p a r t i c u l a r l y in the m a n n e r by which the pilot i s r e q u i r e d to show
that he h a s the r e q u i s i t e knowledge. T h e r e f o r e , the Board r e c o m m e n d s
that:
3.
The FAA continue to e m p h a s i z e the i m p o r t a n c e of the
p r o v i s i o n s of Part 121.445 in i t s s u r v e i l l a n c e and i n s p e c t i o n
of flight o p e r a t i o n s under P a r t 121. Such e m p h a s i s is needed
to a s s u r e that t h e s e o p e r a t o r s a r e (1) using the b e s t m e a n s
available t o enable pilots to qualify under 121.445, and ( 2 ) r e quiring p i l o t s t o show that they have a c q u i r e d the r e q u i s i t e
knowledge p r i o r to completion of a flight r e l e a s e .
F i n a l l y , the Board w i s h e s to acknowledge and e x p r e s s continuing s u p p o r t
f o r the long t e r m S t a t i c P r e s s u r e M e a s u r e m e n t s P r o j e c t u n d e r t a k e n by the
National A e r o n a u t i c s and Space A d m i n i s t r a t i o n at the L e w i s R e s e a r c h C e n t e r .
The Board b e l i e v e s that t h e s e t e s t s and similar e f f o r t s by o t h e r organizations
will provide significant d a t a on the flight and w e a t h e r conditions which might
lead to s t a t i c s y s t e m contamination and altitude m i s i n f o r m a t i o n , a subject
which is i n v a r i a b l y r a i s e d i n connection with landing and a p p r o a c h a c c i d e n t s .
The Board t h e r e f o r e u r g e s that s u c h testing be expedited and will await with
anticipation the r e s u l t s t h e r e o f , which hopefully will shed s o m e light on a n
a r e a that h a s too m a n y unknowns.
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39
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BY THE NATIONAL TRANSPORTATION SAFETY BOARD:
I sI
JOHNH. REED
Chairman
Is1
OSCAR M. LAUREL
Member
I sI
FRANCIS H. McADAMS
Member
I sI
LOUIS M. THAYER
Member
I sI
ISABEL A. BURGESS
Member
April 1 4 , 1972
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40
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APPENDIX A
INVESTIGATION AND HEARING
1.
Investigation
T h e B o a r d r e c e i v e d notification of t h e a c c i d e n t a t a p p r o x i m a t e l y 2025
on November 14, 1970, f r o m the F e d e r a l Aviation A d m i n i s t r a t i o n . An i n v e s t i g a t i n g t e a m w a s i m m e d i a t e l y d i s p a t c h e d to the s c e n e of the a c c i d e n t .
Working g r o u p s w e r e e s t a b l i s h e d f o r O p e r a t i o n s , A i r T r a f f i c C o n t r o l ,
W e a t h e r , W i t n e s s e s , Human F a c t o r s , S t r u c t u r e s , S y s t e m s , P o w e r p l a n t s ,
Maintenance R e c o r d s , and F l i g h t and Voice R e c o r d e r s . I n t e r e s t e d p a r t i e s
included the F e d e r a l Aviation A d m i n i s t r a t i o n ; S o u t h e r n A i r w a y s , Inc. ;
Douglas A i r c r a f t Division; McDonnell-Douglas C o r p o r a t i o n ; A i r L i n e
P i l o t s A s s o c i a t i o n ; and P r a t t & Whitney Division, United A i r c r a f t C o r p o r a tion. T h e o n - s c e n e i n v e s t i g a t i o n w a s c o m p l e t e d on November 23, 1970.
2.
Hearing
A public h e a r i n g w a s held a t Huntington, W e s t Virginia, on D e c e m b e r
14 - 16, 1970. P a r t i e s to t h e Investigation included t h e F e d e r a l Aviation
A d m i n i s t r a t i o n ; S o u t h e r n A i r w a y s , Inc. ; Douglas A i r c r a f t Division,
McDonnell-Douglas C o r p o r a t i o n ; and A i r L i n e P i l o t s A s s o c i a t i o n . T h e
h e a r i n g was r e c o n v e n e d J u n e 2 3 - 25, 1971, i n Washington, D. C.
3.
Preliminary Reports
A s u m m a r y of the t e s t i m o n y which w a s taken a t the f i r s t public h e a r i n g
w a s published by the B o a r d on J a n u a r y 2 5 , 1971. An additional s u m m a r y w a s
r e l e a s e d on July 28, 1971.
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41
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APPENDIX B
C r e w Information
Captain F r a n k H. Abbott, J r . , aged 47, was employed by Southern
A i r w a y s , I n c . , on July 21, 1949. He held airline t r a n s p o r t pilot c e r t i f i c a t e No. 507765 with r a t i n g s i n DC-3', DC-4, DC-9 and M-202/404,
and c o m m e r c i a l p r i v i l e g e s i n single-engine land a i r p l a n e . He a l s o held
a flight i n s t r u c t o r c e r t i f i c a t e with a i r p l a n e and i n s t r u m e n t r a t i n g s , He
had a c c u m u l a t e d a p p r o x i m a t e l y 18, 557 total flying h o u r s , including 2,194
h o u r s in the DC-9. He completed his l a s t p r o f i c i e n c y c h e c k on October
14, 1970, and h i s FAA f i r s t - c l a s s m e d i c a l c e r t i f i c a t e w a s i s s u e d on
October 22, 1970, with the l i m i t a t i o n t h a t the holder s h a l l w e a r c o r r e c t i n g
l e n s e s while e x e r c i s i n g the p r i v i l e g e s of the c e r t i f i c a t e .
F i r s t Officer J e r r y R. S m i t h , aged 28, was employed by Southern
A i r w a y s , I n c . , on A p r i l 12, 1965. He held c o m m e r c i a l pilot c e r t i f i c a t e
No. 1581568 with a i r p l a n e single-engine land and i n s t r u m e n t r a t i n g s . He
had a c c u m u l a t e d a p p r o x i m a t e l y 5, 872 total flying h o u r s , including 1,196
h o u r s in the DC-9. He completed his l a s t p r o f i c i e n c y c h e c k on July 14,
1970, and h i s FAA f i r s t - c l a s s m e d i c a l c e r t i f i c a t e was i s s u e d on November
5, 1969, without l i m i t a t i o n s . It was s t i l l valid as a s e c o n d - c l a s s m e d i c a l
c e r t i f i c a t e a t the t i m e of the accident.
Captain Abbott and F i r s t Officer S m i t h had r e s t p e r i o d s of a p p r o x i m a t e l y
20 and 18 h o u r s , r e s p e c t i v e l y , p r i o r to r e p o r t i n g f o r duty f o r this o p e r a t i o n .
At the t i m e of the accident, both had b e e n on duty five h o u r s , of which two
h o u r s , 21 m i n u t e s , w e r e flight t i m e .
S t e w a r d e s s P a t Vaught w a s employed by Southern A i r w a y s , I n c . , on
J u n e 11, 1962. Her l a s t r e c u r r e n t training was completed on October 21,
1970.
S t e w a r d e s s C h a r l e n e P o a t was employed by Southern A i r w a y s , I n c . , on
M a r c h 28, 1964. Her l a s t r e c u r r e n t t r a i n i n g was completed on October 2 2 ,
1970.
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42
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APPENDIX C
A i r c r a f t Information
N97S, a McDonnell-Douglas DC-9- 31, was d e l i v e r e d to S o u t h e r n
Airways on J u n e 20, 1969. It had b e e n flown a t o t a l of a p p r o x i m a t e l y
3, 667 h o u r s p r i o r to the accident. P r a t t & Whitney J T 8 D - 7 engines
w e r e i n s t a l l e d as follows:
Position
S e r i a l No.
Total Time
T o t a l No. C y c l e s
1
2
P-657140D
P-657297D
5, 030. 8
4,533.9
8,473
8,120
T h e a i r c r a f t weighed 95, 795 pounds 8 / a t takeoff and the c e n t e r of
g r a v i t y (,c.g. ) w a s 18.4 p e r c e n t MAC. T h e maximum allowable weight
l i m i t s w e r e 97, 344 pounds f o r takeoff ( b a s e d on runway length) and
93, 254 pounds f o r landing on a wet runway a t Hungtington. T h e c. g.
l i m i t s w e r e 6 p e r c e n t MAC and 32 p e r c e n t MAC. The computed landing
weight w a s 89, 235 pounds with a c . g. of 17.12 p e r c e n t MAC. In a c c o r d a n c e with c o m p a n y p r o c e d u r e s , the a c t u a l weights of the p a s s e n g e r s w e r e
u s e d i n the computation of t o t a l p a s s e n g e r weight.
The actual stopping p e r f o r m a n c e f o r the DC-9-30 w a s computed by
DAC 0 f o r the following conditions: (1) landing weight 89, 235 pounds ,
( 2 ) f i e l d elevation 828 f e e t , ( 3 ) runway w e t and g r a d i e n t z e r o , (4)
t h r e s h o l d s p e e d 126 knots and c o n t a c t s p e e d 1. 25/1. 30 t i m e s t h r e s h o l d
s p e e d , ( 5 ) t e m p e r a t u r e 49O, ( 6 ) 80 p e r c e n t w o r n t i r e s , and ( 7 ) both
engines at maximum continuous r e v e r s e t h r u s t until 60 knots and then
1 . 2 E P R r e v e r s e t h r u s t . C o r r e s p o n d i n g landing d i s t a n c e s w e r e a l s o
computed, a s s u m i n g touchdown 1, 000 feet f r o m t h e start of the runway.
Tailwind (knots)
Stopping D i s t a n c e
Landing D i s t a n c e
8/
0
2,634
3,634
5
2, 712
3, 712
3
2,686
3,686
T h i s weight is b a s e d on the actual o p e r a t i n g weight of the a i r c r a f t ,
r a t h e r than the published a i r c r a f t o p e r a t i n g weight. Consequently,
i t is s l i g h t l y h i g h e r than the 9 5 , 2 6 3 pounds computed by the c r e w .
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43
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TRANSCRIPTION OF COCKPIT VOICE RFCORDER W E
N g S , HUNTINGTON, WEST VIRGINIA, NOVEMBER 14,
-- DOUGLAS DC-9,
1970, E A 71-A-5
LEGEND
%
CAM
RDO
-1
-2
-3
-?
EmfS
IND
*
0
CRW
------
-
Break i n continuity
Cockpit area microphone sound source
Radio transmission from N97S
Voice i d e n t i f i e d as captain
Voice i d e n t i f i e d as f i r s t o f f i c e r
Voice i d e n t i f i e d as a d d i t i o n a l crewmember
Voice u n i d e n t i f i e d
Huntington Approach Control
Indianapolis Center
U n i n t e l l i g i b l e word o r phrase
Words within parentheses are sLibject t o
further interpretation
Charleston Tower
TIME
-
SOURCE
1916:59.9
RDo-1
Charleston Tower, this i s Southern nine thirty-two.
CRW
Southern nine thirty-two, Charleston Tower
RDO-1
We're going wer t o Huntington, we passed just
south of Charleston.
got down t h e r e now?
What kind of weather you
CRW
Charleston weather estimated c e i l i n g six thousand
broken, v i s i b i l i t y four, ground fog and smoke.
RDO-1
What's1 your spread?
CRW
Temperature f i v e zero, dew p o i n t f o u r nine.
RDO-1
Thank you.
RDO-1
Look l i k e i t ' s going t o hold up a w h i l e ?
CRW
Sure t h i n g .
CAM-2
Sounds l i k e a g a l .
CAM-1
It i s .
CAM-1
Broken up here a t Charleston.
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44
-
TIME
I
_
1919:00.2
comms
SOURCE
CAM-2
Yeah, i t ' s gotten a l o t b e t t e r . Maybe i t ' s g o t t e n
b e t t e r over here, i t ' s not t o o far away.
CAM4
You might t r y it again.
RDO
Sound of tuning of ADF.
m-2
Southern nine t h i r t y two out of eleven thousand
f i v e hundred
$%$
CAM-1
Approach p l a t e ' s two years o l d .
CAM-2
Yeah
CAM-2
On t h e s e c h a r t e r kits they don't keep those
****
things up l i k e t h e y ' r e supposed t o .
CAM
Sound of l a u g h t e r .
CAM-1
How many miles you got t o P u l a s k i ?
CAM-2
About t o run out
CAM-2
I t ' s p o i n t i n g that way, Frank.
on it, though.
CAM-1
Let's run t h e rest of t h e in-range check.
CAM-1
How many miles you got on it? I c a n ' t
***
Can't get a code
* * * it's
gone o f f .
1W:57.3
CAM-2
Yeah, i t ' s gone off
CAM-2
(Bugs) one two t h r e e .
CAM-1
Put Charleston on yours
mo-1
Center, Southern nine t h i r t y two
IND
Southern nine t h i r t y two, descend and maintain
five thousand, say a g a i n .
-
45
-
***
TJME
SOURCE
1922:02.7
mo-2
Okay, Southern nine thirty-two, we're out of
e i g h t now, we're going t o f i v e , and approximately
how far do you show us from t h e Huntington Airport?
1922:Og.T
IND
Nine thirty-two approximately twenty miles southeast of Huntington A i r p o r t .
RDO-2
Roger.
IND
Southern nine t h i r t y two squawk zero f o u r zero
zero, contact Huntington Approach Control one two
zero p o i n t niner, r a d a r s e r v i c e terminated.
RDO-2
One two zero point nine, g o d day s i r .
CAM-1
Here we go.
RDO-2
Huntington Approach, Southern nine thirty-two,
we're descending t o f i v e thousand.
HTS
Southern nine t h i r t y two, Huntington Approach
Control, you're cleazed f o r an approach, correction,
you're cleared f o r a l o c a l i z e r one one approach,
t h e surface wind's favoring runway two nine, wind
three f i v e zero degrees a t six, altimeter two nine
s i x seven, r e p o r t leaving f i v e thousand. I'll
give you t h e weather s h o r t l y .
m-2
Okay, we got t h e altimeter and w e ' l l check with
you leaving f i v e thousand, we plan on approach t o
one one.
HTS
Roger.
RDO
Sound of ILS l o c a l i z e r i d e n t i f i c a t i o n .
HTS
Southern nine t h i r t y -two, t h e Huntington weather
three hundred s c a t t e r e d , measured c e i l i n g five
hundred variable broken, one thousand one hundred
overcast, v i s i b i l i t y f i v e , l i g h t r a i n , fog, smoke.
Ceiling ragged, v a r i a b l e f o u r t o s i x hundred.
CAM-?
Phew:
RDO-2
Very w e l l , thank you s i r .
CAM-1
Very w e l l :
CONTENTS
-
46
-
SOURCE
CONTENT
CAM
Sound of l a u g h t e r -
CAM-1
Very well?
CAM-2
Four hundred and twelve.
CAM-1
Yeah, and a m i l e v i s i b i l i t y .
CAM-2
H e said t h e v i s i b i l i t y w a s
CAM-2
I'll ask him a g a i n -
RDO-2
What's your v i s i b i l i t y again?
CAM-1
* * * and
HTS
V i s i b i l i t y f i v e , l i g h t rain, fog, smoke.
mo-2
:
**
twenty-six hundred from a l l d i r e c t i o n s .
Right.
--------- r i g h t
on t h e minimums
***
CAM-1
Right on t h e
CAM-1
See i f you can g e t that t h i n g tuned i n a l i t t l e
b i t better, s o r t of wavering.
CAM-2
All r i g h t .
RDO-2
Southern nine t h i r t y two i s out of f i v e .
€ITS
Out of f i v e , r e p o r t o u t e r w k e r outbound.
FDO
Sound of ILS o u t e r compass l o c a t o r i d e n t i f i c a t i o n -
CAM-2
Localizer i s one oh nine nine,
inb ound
CAM-1
Wonder how many miles it i s t o Kanawha?
CAM-2
Stand by.
CAM-2
Charleston's not b u t about f i f t y miles
CAM-1
You got Charleston s e t on yours?
CAM-2
Charleston's set on
CAM-1
Damn close.
---- one fourteen
I
-
,
k,
47
-
***
about t h i r t y
* * *.
TIME
-
coNTm
CAM-2
Ought t o be g e t t i n g p r e t t y damn close 'cause he
gave us twenty miles r i g h t back there. T h a t ' s
been f o u r o r f i v e minutes.
CAM-2
You're g e t t i n g s l a n t
CAM-2
***
CAM-2
Marker's i d e n t i f i e d .
---- s l a n t range on it.
%%%
1926 9 4 . 5
1926:43.1
1927:58 99
How many you got?
CAM-2
Forty-two DME.
CAM-1
Thirty-seven.
CAM-1
Coming over middle marker.
CAM-2
Middle marker t h e r e .
CAM-3
Frank, you want full f u e l load out of here?
CAM-1
Might as w e l l
CAM-2
M i n i m u m i s nineteen
charge us?
CAM-3
Well, we get contract price, whatever t h a t i s ,
whatever we pay for i t .
CAM-2
We got a mile o r two t o go, Frank, 's a l l .
CAM-?
Yeah.
CAM-1
We're showing on t h e l o c a l i z e r .
CAM-3
Hope we don't have t h i s a l l t h e w a y i n .
CAM-2
There she i s .
mo-2
Southern nine t h i r t y two, we're over t h e marker
now, proceeding outbound.
HTS
Southern nine thirty-two,
marker inbound
(Note:
CAM-1
---- wonder how much t h e y ' l l
I t ' s rough.
Fager, report t h e
Underlined words above and below spoken
s imdtaneous l y )
--S l a t s and f i v e .
-
48 -
CONTENT
RDO-2
Very well.
1928: 11.0
CAM-1
S l a t s and five.
1928:35 06
CAM-1
( F r m t h e ) l i g h t s on t h e ground (it looks l i k e ) fog.
CAM-2
Makes it sorry, doesn't i t ?
CAM-1
You checked t h e missed approach?
CAM-2
A l l r i g h t , you p u l l up t o twenty-seven hundred
f e e t by t h e east course of t h e ILS t o Shoals,
Shoals Fan Marker, report Shoals then s t r a i g h t
out
***
CAN-1
*
*
CAM-2
Sound of Laughter.
CAM-2
Well, I don't know.
1930:03 00
CAM-2
(I b e l i e v e ) half those l i g h t s should be off t o
our l e f t . Kinda hard t o say, though.
1930:43.6
CAM-^
We're i n a rahshower, a l l r i g h t .
CAM-2
Yeah, I know it.
w-1
W
e sure are.
CAM-2
Yeah, ah, t M t r a i n i s (mixed) i n wZth fog.
CAM
Sound of windshield wipers commences.
CAM
Sound of landing gear i n transit commences
CAM-2
Okay, you got t h e no smoking, i g n i t i o n , radar
standby, auto shutoff armed, waiting on t h e gear
got t h e s p o i l e r s ?
CAM-?
1930: 49.6
The temp ( i s dropping).
-----
1931:26.2
CAM-1
Armed
CAM
Sound of c l i c k similar t o that of arming spoilers.
CAM-2
Checked, out.
CAM4
T h a t t h i n g captured!
-
49
-
How did it capture?
TIME
-
SOURCE
CAM-2
Yeah, it ought t o .
CAM-1
You g e t t i n g a g l i d e slope capture and you a i n ' t
got a g l i d e s l o p e .
CAM-?
1931:49.8
CONTENT
*
CAM-2
I might capture on the, ah, on ILS, ah, Frank,
regardless of g l i d e slope. I don't have no
capture, though.
CAM-1
Okay, give me, ah, twenty-five
CAM-2
Yeah, i t ' s good, i t ' s got t h e capture.
CAM-?
*
CAM-1
I got it cut off t h e r e now.
CAM-2
Got twenty-five f l a p s , a l l i s squared.
CAM-1
W e ought t o be over the outer marker a t twenty
two hundred f e e t
CAM-2
Yeah
CAM-3
I ' m sorry, Frank.
CAM-1
You going t o c a l l out minimums?
CAM-2
Yeah, I sure w i l l .
CAM-2
As you g e t on down it, ah, this rough a i r ought
t o give us a l i t t l e break.
CAM-1
Well, i f i t ' s l i k e he s a i d , i t ' s not blowing any
harder than he says it i s , why
*
*
Ill1 s i n g ' e m out t o you.
--I-
CAM-2
Down d r a f t .
CAM-1
It took us down t o t h e marker level.
CAM-?
Yeah, that's enough.
CAM-?
Yeah
1933:17 9
CAM-1
M u s t be a l i t t l e rainshower.
1933:19 9
CAM-2
Back i n t h e soup.
-
50
-
---
TIME
-
SOURCE
CONTENT
CAM-1
Jerry, I'm going t o be f l y i n g about one t h i r t y .
CAM-2
I ' m going t o check t h e t i m e for you. I t ' l l b e
about two minutes from the, ah, outer marker *
Sound of outer marker begins.
Sound of outer marker ceases abruptly.
Southern nine thirty-two the marker inbound.
*
Southern nine thirty-two i s cleared t o land.
You can advise on t h e l i g h t s , t h e wind i s now
three f o u r zero degrees seven.
1933:59.1
1934:09.2
193k32.4
CAM
Sound sirnilax t o c l i c k of f l a p s e l e c t o r .
RDO-2
Okay, t h e l i g h t s be good about s t e p three, I guess.
H!PS
Roger, that's where they are, with t h e r a b b i t .
Advise when you want them cut.
RDO-2
Very good.
CAM-2
On t h e bug.
CAM-3
* rough-
CAM-1
T h i s autopilot a i n ' t responding just r i g h t
Sluggish*
CAM-2
Yeah.
CAM-1
Might catch up.
CAM-;!
Okay, I got the t i m e for you.
CAM-2
A thousand f e e t above t h e ground, rate and speed
good-
CAM-2
Speed a l i t t l e fast, looks good,
bug and twelve.
See sanething?
-
51
-
_---
(1934:45.2) got
TIME
_
I
_
SOURCE
-
CONTENT
CAM-2
No, not yet. I t ' s beginning t o l i g h t e n up a
L i t t l e b i t on t h e ground here a t , ay, ah,
(1935:01.6) seven hundred feet.
1935:03.2
CAM-2
Bug and f i v e .
1935: 06.8
CAM-2
We're two hundred above.
1935:i o .6
CAM-3
B e t '11 be a missed approach.
1935:18.2
CAM-2
Four hundred.
1935:1-9 3
CAM-1
That t h e approach?
CAM-2
Yeah.
1935 :21.3
CAM-2
Hundred and twenty s i x ,
1935:25.7
CAM-2
HUNDRED
1935:26.5
CAM
Sounds of impact begin.
1935:32 5
End of recording.
-
52
-
APPENDIX E
EFFECT OF STATIC SYSTEN RESTRICTION OR
BLOCKAGE ON AIRSPEED INDICATION
The magnitude of t h e e r r o r i n i n d i c a t e d a i r s p e e d which w i l l e x i s t as
a result of a s t a t i c system pressure e r r o r i s c a l c u l a t e d f o r two assumed
values of i n d i c a t e d a l t i t u d e error.
Condition 1:
The nonstandard day Q,NH altimeter s e t t i n g i s 29.67 inches Hg.
The a l t i t u d e of t h e a i r c r a f t i s 916 f e e t m.s.1.
t o a l t i t u d e of i n i t i a l impact).
(which corresponds
The i n d i c a t e d a l t i t u d e i s 1,240 f e e t
m.s .l. (which corresponds t o t h e published m i n i m u m descent a l t i t u d e ) .
If this e r r o r i s a result of a pressure d i f f e r e n c e between ambient
and t h a t measured within t h e a i r c r a f t s t a t i c system, t h e corresponding
i n d i c a t e d a i r s p e e d error i s found as follows:
The airspeed i n d i c a t i o n i s based upon t h e following equation:
Where:
qc
=
d i f f e r e n t i a l pressure, inches Hg.
Pt = f r e e stream t o t a l ( P i t o t ) pressure, inches Hg.
ambient ( s t a t i c ) pressure, inches Hg.
Pa
standard day s e a l e v e l pressure, 2 9 . 9 l i n . Hg.
Vc
=
a
- s e a l e v e l speed of
c a l i b r a t e d airspeed, knots
s 1-
S u b s t i t u t i n g Vc
qC
or
661.48 knots
= 130 knots i n t o equation
= .8168
Pt :Pa
sound,
/
i n . Hg.
.8168 i n . Hg.
-
53
-
(1)y i e l d s
APPENDIX E
From the United States Standard Atmosphere Table:
Pa”as 1 f o r 1,240 f e e t m.s.1.
For a nonstandard day when &NH
P
a
f o r 1,240 f e e t m.s.1.
A l s o Pa/Pasl
e
equals .9560
29.67 i n . Hg.
z .9560 x 29.67
-
28.364 i n . Hg.
f o r 916 feet m.s .l. equals .9673
For t h e same nonstandard day:
Pa f o r 916 f e e t
=
.$73
x
29.67 :28.700 i n . Hg.
Thus for the airspeed i n d i c a t o r t o read 130 knots when the s t a t i c
system senses a pressure of 28.364 i n . Hg. (1,240 f e e t ) , the P i t o t
system pressure m u s t be (from eq. 2 )
Pt
Pt
=P
{ .8168
“1,240
29.1813 i n . Hg.
I
= 28.364 { .8168
Assuming that t h e aircraft now descends t o
916 f e e t m.s.1.
and t h e
s t a t i c system continues t o sense a pressure equivalent t o 1,240 f e e t
(28.364 i n . Hg.),
m.s.1.
i f t h e p i l o t controls the aircraft s o that
his airspeed i n d i c a t o r continues t o read
130 knots, the P i t o t system
pressure Pt m u s t a l s o remain constant (29.1813 i n . Hg.).
To determine the a c t u a l a i r c r a f t velocity, i.e.,
the airspeed that
would be i n d i c a t e d i f the s t a t i c system w a s sensing the correct pressure
corresponding t o 916 f e e t (28.700 i n . Hg.),
Pt
=
P
= 28.700 i n . Hg.
29.1813 i n . Hg.
“916
or
qc
qC
-
Pt
- P“916 = 29.1813 - 28.700
.4813 i n . Hg.
-
54
-
f i n d 4,:
APPENDIX E
S a s t i t u t i n g i n t o eq. (1)and s o l v i n g f o r
vc =
vC
yields:
100 knots
Thus for conditions s t a t e d , t h e actual v e l o c i t y of t h e a i r c r a f t
would be 100 knots, a n e r r o r of -30 knots.
Condition 2:
For t h e same nonstandard day, QNH altimeter s e t t i n g e q u a l 29.67
inches Hg., t h e a c t u a l v e l o c i t y of t h e a i r c r a f t i s c a l c u l a t e d f o r a
corresponding a l t i t u d e e r r o r of 200 feet.
From equation (1)above, f o r Vc :130 knots
qC
= .8168
pa/Pasl
a
'
i n . Hg.
for 1,240 f e e t m.s.1.
equals .9560
:28.364 i n . Hg.
1,240
From t h e United S t a t e s Standard Atmosphere Table:
Pa'Pas 1 f o r 1,040 feet m.s.1.
For t h e &NH
=
equals .9629
29.67 i n . Hg. condition:
pa f o r 1,040 feet
=
=
.9629 x 29.67
28.570 i n . Hg.
'a 1,040
From condition (1)above :
+ .8m =
pt
= 29.1813
28.364
/
.a168
i n . Hg.
Assuming that t h e a i r c r a n descends t o 1,040 f e e t m.s.1.
and t h e
s t a t i c system continues t o sense a pressure equivalent t o 1,240 f e e t
m.s.1.
(28.364 i n . Hg.), i f t h e p i l o t c o n t r o l s t h e a i r c r a f t s o that
-
55
-
APPENDIX E
his airspeed i n d i c a t o r continues t o read 130 knots, t h e a c t u a l a i r c r a f t
v e l o c i t y i s found as follows:
29.1813 in. Hg.
pt
P
0
28.570 i n . Hg.
040
qc
:.
6 ~ 3in Hg.
S u b s t i t u t i n g i n t o eq. (1)and solving f o r V, y i e l d s :
vc =
112.5 knots
Thus f o r conditions s t a t e d , the a c t u a l v e l o c i t y of t h e a i r c r a f t
would b e 112.5 knots, an e r r o r of
-17.5 knots.
- 56 -
Appendix F
page
113
A I R CARRIER OPERATIONS BULLETIN NO. 71-9
SUBJECT:
T r a i n i n g Emphasis on N o n - P r e c i s i o n Approach P r o c e d u r e s and
I n t e r p r e t a t i o n o f Low V i s i b i l i t y Weather R e p o r t s .
R e c e n t a i r c a r r i e r a c c i d e n t s which o c c u r r e d d u r i n g n o n - p r e c i s i o n a p p r o a c h e s
p i n p o i n t t h e need f o r a c t i o n t o improve t h i s t y p e o f o p e r a t i o n . A s t u d y
was i n i t i a t e d sometime back w i t h a g o a l t o examine e x i s t i n g c r i t e r i a and
make recommendations f o r c h a n g e s t o c r i t e r i a . The s t u d y g r o u p must
d e t e r m i n e i f improvements c a n be made which w i l l a i d t h e p i l o t i n making
a d e c i s i o n t o d e s c e n d below MDA d u r i n g a n o n - p r e c i s i o n a p p r o a c h . Meanwhile,
t h e r e i s a need t o r e e m p h a s i z e t r a i n i n g i n n o n - p r e c i s i o n a p p r o a c h e s as w e l l
a s i m p r o v i n g t h e knowledge and u n d e r s t a n d i n g o f t h e i m p l i c a t i o n s , . o f r e p o r t e d
low v i s i b i l i t y w e a t h e r .
A c c i d e n t i n v e s t i g a t o r s from t h e NTSB and i n s p e c t o r s from t h e Washington
O f f i c e have q u e s t i o n e d a i r c a r r i e r p i l o t s a b o u t t h e meaning and i m p l i c a t i o n
of r e p o r t e d o b s c u r a t i o n i n w e a t h e r s e q u e n c e s . The p i l o t r e s p o n s e r e f l e c t e d
i n a d e q u a t e knowledge o f t h e s u b j e c t . Of p a r t i c u l a r i n t e r e s t i s t h e f a c t
t h a t p a r t i a l o b s c u r a t i o n i s d e s c r i b e d i n t h e r e m a r k s e c t i o n and c a n be
a n y t h i n g from 1/10 t o 9/10 c o v e r a g e a n d s t i l l be c o n s i d e r e d p a r t i a l . The
i m p l i c a t i o n o f a 7/10 o r 8/10 o b s c u r a t i o n i s t h a t a p i l o t c o u l d r e a s o n a b l y
e x p e c t t o e n c o u n t e r r e s t r i c t i o n s t o v i s i b i l i t y a s he d e s c e n d s from a
p o s i t i o n below c l o u d l e v e l toward t h e runway e n v i r o n m e n t . However, p i l o t s
q u e s t i o n e d were n o t aware o f t h i s b e c a u s e t h e y d i d n o t r e l a t e t h e remarks
information t o t h e obscuration.
I n v i e w o f t h e l a c k o f knowledge on t h e p a r t o f t h e p i l o t s i n t e r v i e w e d ,
o p e r a t i o n s i n s p e c t o r s s h o u l d a s s u r e t h a t t r a i n i n g programs a d e q u a t e l y c o v e r
w e a t h e r s e q u e n c e s and i n t e r p r e t a t i o n s t h a t may be made from t h e low
v i s i b k l i t y d a t a s u p p l i e d on t h e weather sequence.
The FAA Academy h a s p r e p a r e d a p a p e r on n o n - p r e c i s i o n a p p r o a c h e s which cont a i n s e x c e l l e n t material t o a s s i s t i n u p g r a d i n g t h e p r o f e s s i o n a l i s m r e q u i r e d
d u r i n g a n o n - p r e c i s i o n a p p r o a c h . The material i s r e p r o d u c e d i n p a r t a s
follows:
THE NON-PRECISION INSTRUMENT APPROACH
MORE P1XCISION I S NEEDED
-
-
The a b i l i t y t o c o n d u c t t h e n o n - p r e c i s i o n a p p r o a c h i n a p r o f e s s i o n a l manner
h a s g i v e n way i n l a r g e p a r t t o the computed and a u t o m a t e d a p p r o a c h e s ; i . e . ,
f l i g h t d i r e c t o r and a u t o c o u p l e d a p p r o a c h e s . The i n s t r u m e n t p i l o t o f t o d a y
i s b e i n g t r a i n e d i n a manner which e m p h a s i z e s t h e p h i l o s o p h y o f t h e p r e c i s i o n
- 57 -
Appendix F
Page 114
ILS a p p r o a c h t o C a t e g o r y I , XI and I11 p r o c e d u r e s and w e a t h e r minima, b u t
de-emphasizes t h e b a s i c n o n - p r e c i s i o n i n s t r u m k n t a p p r o a c h p r o c e d u r e s . H i s
t r a i n i n g no l o n g e r stresses t h e need f o r p r e c i s e t i m i n g , c l o s e l y c o n t r o l l e d
r a t e s o f d e s c e n t , t h o r o u g h knowledge o f t h e p r o c e d u r e , and t h e b a s i c s k i l l s
and t e c h n i q u e s o f u s i n g t h e raw d a t a i n f o r m a t i o n d i s p l a y e d i n t h e c o c k p i t .
A s a r e s u l t , he h a s become i n f a r t o o many cases, s o m e t h i n g l e s s t h a n a prof e s s i o n a l i n conducting t h e non-precision approach.
What can be done t o r e v e r s e t h i s t r e n d ? One way would be t o re-emphasize
t h e need t o know and practice t h e b a s i c s k i l l s and t e c h n i q u e s a s s o c i a t e d
w i t h t h e n o n - p r e c i s i o n a p p r o a c h . A n o t h e r c o u l d be t o r e c o g n i z e t h e need f o r
more p r e c i s i o n d u r i n g t h e s o - c a l l e d n o n - p r e c i s i o n a p p r o a c h . Even a name
change f o r t h i s t y p e p r o c e d u r e ( s ) may be i n o r d e r . P e r h a p s we s h o u l d s t o p
u s i n g t h e p h i l o s o p h y o f n o n - p r e c i s i o n and face up t o t h e need f o r s t a n d a r d s
t h a t a l l p h a s e s o f f l i g h t s h o u l d be based upon p r e c i s i o n a n d p r o f e s s i o n a l i s m .
S t i l l a n o t h e r area i n t h e c o n d u c t o f n o n - p r e c i s i o n a p p r o a c h h a s t o d o w i t h
t h e a t t i t u d e , c o c k p i t d i s c i p l i n e and crew c o o r d i n a t i o n o f t h e f l i g h t crew.
Recent e v e n t s s t r o n g l y i n d i c a t e a w i d e s p r e a d l a c k o f a p p r e c i a t i o n f o r t h e
importance o f t h e s e f a c t o r s . S u b s t a n d a r d a t t i t u d e , d i s c i p l i n e and c o o r d i n a t i o n are a p p a r e n t t o t h e d e g r e e t h a t many a p p r o a c h e s a r e b e i n g flown i n a
h i t - o r - m i s s f a s h i o n r a t h e r t h a n i n a d i s c i p l i n e d by-the-book p r o c e d u r e . The
r e s u l t s i n f a r t o o many i n s t a n c e s have 6 e e n making newspaper h e a d l i n e s . T h i s
area i n p a r t i c u l a r is i n g r e a t need o f added e m p h a s i s .
I n a d d i t i o n t o t h e p r e c e d i n g p o i n t s , more o p e r a t i o n a l knowledge o f t h e
c o n s t r u c t i o n o f t h e n o n - p r e c i s i o n a p p r o a c h as s p e l l e d o u t i n t h e TERPS
Handbook 8 2 b O . U , is needed. Such t h i n g s a s o b s t r u c t i o n c l e a r a n c e s , d e s c e n t
g r a d i e n t s , f i n a l c o u r s e a l i g n m e n t c r i t e r i a , and t h e p r i m a r y b o u n d a r i e s o f the
a p p r o a c h segments are need-to-know f a c t o r s f o r t h e p r o f e s s i o n a l a i r m a n .
What a r e some o f t h e shortcomkngs and common f a u l t s f r e q u e n t l y n o t e d i n t h e
execution of non-precision approaches?
1.
F a i l u r e t o c o n d u c t comprehensive b r i e f i n g on t h e a p p r o a c h p r o c e d u r e
and t e c h n i q u e s t o be u s e d .
2.
F a i l u r e t o e x e c u t e t h e p r o c e d u r e s as p u b l i s h e d ; i . e . , c u t t i n g t h e
p r o c e d u r e s h o r t , e s p e c i a l l y when t h e i n i t i a l phase i s on t o p o f t h e
r e s t r i c t i o n t o v i s i b i l i t y . T h i s c o r n e r c u t t i n g carries o v e r i n t o
t h e f i n a l a p p r o a c h phase where a l l a t once e v e r y t h i n g p i l e s up and
t h e crew is n o t a l w a y s e q u a l t o t h e t a s k .
3.
F a i l u r e t o c r o s s - c h e c k a l t i m e t e r s and o t h e r f l i g h t i n s t r u m e n t s
d u r i n g t h e i n i t i a l and f i n a l a p p r o a c h e s .
#
4. Using p r o c e d u r e s and t e c h n i q u e s which g i v e t h e p i l o t t o o much t o
d o a t t h e s t a r t o f t h e f i n a l a p p r o a c h segment; i . e . , c h e c k i n g t h e
f i n a l a p p r o a c h f i x p a s s a g e ; c a l l i n g f o r g e a r down and b e f o r e l a n d i n g
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58
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F
c h e c k l i s t ; c a l l i n g f o r a p p r o a c h o r l a n d i n g f l a p s as a p p r o p r i a t e ;
commencement o f t i m i n g i f r e q u i r e d ; commencement of t h e r e q u i r e d
a t least
d e s c e n t rate; e s t a b l i s h m e n t o f c o r r e c t a i r s p e e d ; e t c . ,
s i x t h i n g s which must be accomplished i n s h o r t o r d e r . E x p e r i e n c e
h a s shown t h a t one o r more of t h e s e items a r e o f t e n u n i n t e n t i o n a l l y
d e l a y e d o r f o r g o t t e n , u s u a l l y t o t h e d e g r a d a t i o n of t h e o v e r a l l
q u a l i t y of the approach.
-
5.
F a i l u r e t o t u n e and p r o p e r l y i d e n t i f y t h e a p p r o a c h f a c i l i t y ( s ) .
6.
F a i l u r e t o p r e c i s e l y n o t e FAF p a s s a g e .
7.
F a i l u r e t o commence t i m i n g a t t h e FAF.
#
8.
F a i l u r e t o promptly commence a p r o p e r l y c o n t r o l l e d and c o r r e c t
r a t e o f d e s c e n t so as t o a r r i v e a t MDA i n a p o s i t i o n t o s i g h t
t h e runway environment and c o n t i n u e a normal a p p r o a c h t o a l a n d i n g
so as t o a v o i d e x c e s s i v e l y h i g h r a t e s o f d e s c e n t a t a n y p o i n t
d u r i n g t h e f i n a l a p p r o a c h segment.
9.
I n a t t e n t i o n t o t h e d e t a i l s o f t h e t a s k a t hand; e . g . , c o n v e r s a t i o n
and a c t i o n s c o n c e r n i n g u n r e l a t e d and i r r e l e v a n t t h i n g s .
10. O p p o s i t e c o r r e c t i o n s t o t a i l ADF b e a r i n g s .
11.
Poor q u a l i t y o f ADF maintenance and dpkeep; e . g . , t h e o f t - h e a r d
remark t h a t , " t h e ADF i s no good i n t h e modern j e t s , " when a l l i t
l i k e l y needs i s t o be G r i t t e n up and c a r e f u l l y r e p a i r e d .
12. Lack o f a p p r e c i a t i o n o r knowledge f o r t h e d i f f e r e n t scale v a l u e s
o f t h e l o c a l i z e r and VOR as d i s p l a y e d on t h e Course I n d i c a t o r .
13.
F a i l u r e t o c a r r y o u t p r o p e r crey c o o r d i n a t i o n procedures,.
E s p e c i a l l y , when t h e c o p i l o t i s f l y i n g t h e C a p t a i n o f t e n f a i l s t o
e x e c u t e t h e normal c o p i l o t f u n c t i o n s and d u t i e s .
14. Not s t a y i n g on i n s t r u m e n t s ; i . e . , b o t h pi1,ots l o o k i n g o u t f o r t h e
runway t h r e s h o l d r a t h e r ' t h a n one s t a y i n g on i n s t r u m e n t s and t h e
o t h e r c r o s s - c h e c k i n g and l o o k i n g o u t f o r t h e runway e n v i r o n m e n t .
15.
I n a t t e n t i o n t o p r e c i s e c o u r s e i n t e r c e p t i o n , and c r o s s - c h e c k i n g on
secondary instruments.
16.
Failure t o level off
17.
Persistence i n continuing a substandard approach r a t h e r than
promptly e x e c u t i n g t h e missed a p p r o a c h . There seems t o be a
s t r o n g - f e e l i n g f a l s e p r i d e a g a i n s t e x e c u t i n g a missed a p p r o a c h .
o r s l i g h t l y above MDA.
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59
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Appendix F
Page 116
18. Not u s i n g a s t a b i l i z e d approach c o n c e p t .
19.
Not p r e p l a n n i n g how t o conduct t h e approach so as t o f l y t h e a i r p l a n e through t h e wdndow (key p o i n t ) a t MDA a p p r o x i m a t e l y one m i l e
from t h e runway t h r e s h o l
9.
20. Not s t r i v i n g f o r a h i g h d e g r e e o f a c c u r a c y and p r e c i s i o n i n t h e
conduct o f t h e n o n - p r e c i s i o n a p p r o a c h .
21.
Not g i v i n g due c o n s i d e r a t i o n t o t h e ' p o s s i b l e a d v e r s e e f f e c t o f
remote-source w e a t h e r and a l t i m e t e r s e t t i n g i n f o r m t i o n .
RECOMMENDATIONS.
1. Emphasize t h e need f o r more d i s c i p l i n e , crew c o o r d i n a t i o n and
precision i n the various non-precision approaches.
2.
Develop new and more s p e c i f i c crew-concept p r o c e d u r e s f o r
n o n - p r e c i s i o n a p p r o a c h e s similar t o t h e p r o c e d u r e s b e i n g used on
t h e f u l l ILS a p p r o a c h e s . F o l l o w i n g a r e some examples which
a p p a r e n t l y are a p p r o p r i a t e .
,
a.
Complete i n - r a n g e c h e c k l i s t s and comprehensive i n s t r u m e n t
approach b r i e f i n g p r i o r t o i n i t i a t i n g the approach. Careful
c a l c u l a t i o n o f f i n a l a p p r o a c h ground s p e e d .
b.
Extend l a n d i n g g e a r and approach f l a p s and complete b e f o r e l a n d i n g c h e c k l i s t a f t e r i n t e r c e p t i n g inbound c o u r s e and p r i o r
t o FAF p a s s a g e . E s t a b l i s h a l t i t u d e a t t h e minimum recommended
v a l u e so as t o a v o i d s u b s e q u e n t h i g h r a t e s o f d e s c e n t .
c.
Use e s t a b l i s h e d altimeter, f l i g h t i n s t r u m e n t and warning f l a g
c r o s s - c h e c k p r o c e d u r e s j u s t p r i o r t o t h e FAF.
d.
Note FAF p a s s a g e , s t a r t t i m i n g and promptly commence p r e d e t e r m i n e d r a t e of d e s c e n t . S e t l a n d i n g f l a p s i f a p p r o p r i a f e .
e.
Make a l t i t u d e and c o u r s e d e v i a t i o n c a l l o u t s d u r i n g f i n a l d e s c e n t .
f.
c a r e f u l l y monitor t i m i n g and d e s c e n t so as t o a r r i v e a t o r
s l i g h t l y above MDA p r i o r t o t h e KEY POINT (Normally one mile
from t h e runway t h r e s h o l d ) .
The KEY POINT may be determined
by t i m i n g ( u s u a l l y 30 s e c o n d s p r i o r t o MAP), by DME, by c r o s s
b e a r i n g , o r o t h e r type f i x .
g.
POSITIVELY m o n i t o r MDA l i m i t s and d o n o t descend below u n t i l
t h e runway environment i s i n s i g h t and t h e a i r p l a n e is in
p o s i t i o n f o r a NORMAL a p p r o a c h t o a l a n d i n g . Assuming a HAT
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Appendix F
Page 117. o f 300' t o 400', t h i s s h o u l d o c c u r a t t h e KEY POINT and
a p p r o x i m a t e l y one m i l e from the threshold.
Abandon t h e a p p r o a c h and e x e c u t e t h e missed a p p r o a c h p r o c e d u r e
if t h e a p p r o a c h is s u b s t a n d a r d o r if g . above is n o t p o s s i b l e .
It is NOT n e c e s s a r y t o c a r r y o u t t h e t i m i n g t o t h e f i n a l MAP.
3.
C o n s i d e r r e v i s i n g t h e i n s t r u m e n t p r o c e d u r e s and a p p r o a c h p l a t e
d i s p l a y by e s t a b l i s h i n g a KEY POINT FIX (KPF), a p p r o x i m a t e l y one
m i l e from t h e t h r e s h o l d or f a r t h e r o u t where MDA and v i s i b L l i t y
minima are above s t a n d a r d . The f i x may be d e t e r m i n e d by DME, MM,
NDB, i n t e r s e c t i o n , o r by t i m i n g .
4. # C a l c u l a t e and d i s p l a y on a p p r o a c h p l a t e s t h e t i m i n g from FAF t o t h e
Key P o i n t F i x (KPF).
5.
C a l c u l a t e and d i s p l a y on a p p r o a c h p l a t e s t h e r e c o m e n d e d r a t e o f
d e s c e n t r e q u i r e d on f i n a l a p p r o a c h t o r e a c h MDA a t o r b e f o r e t h e
KPF
.
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m
C
0
P
Y
I
XG
NATIONAL TRANSPOR'f'ATION SAFETY BOARD
DEPARTMENT OF TRANSPORTATION
WASHINGTON, D.C.
20591
January 1 7 , 1969
Mr, David D. Thomas
Acting Adcninis t r a t r :
Fed e r a 1 Av i a t i on Adm i n i s t r a t ion
Department of T r a n s p o r t a t i o n
Washington, D. C. 20530
Dear M r . Thomas:
Accidents which occur during t h e approach and landing phase of f l i g h t
continue t o be among t h e most nunerous. They a r e again h i g h l i g h t e d by some
of t h e events of t h e p a s t month t h a t have aroused nationwide i n t e r e s t i n
air s a f e t y . Most approaclh and landing a c c i d e n t s have been a t t r i b u t e d
t o improper o p e r a t i o n z l procedures, techniques, d i s t r a c t i o n s , and f l i g h t
management. In! many cases v e r t i c a l / h o r i z o n t a l wind s h e a r , forms of
turbulence, and a l t i m e t r y d i f f i c u l t i e s were, o r could have been c o n t r i b u t i n g
f a c t o r s . The phenomenon of brea!cing out i n r o v i s u a l f l i g h t conditions and
subseyuentiy becoming involved i n patches of fog, haze, r a i n , blowing snow
and snow showers and other v i s i b i l i t y obscuring forms oE p r e c i p i t a t i o n seems
t o be f a i r l y comnon occurrence, The sensory i l l u s i o n problem a s s o c i a t e d
w i t h n i g h t approaclics over u n l i g h t e d t e r r a i n o r water is another l i k e l y
f a c t o r about which more i s bcing l e a r n e d dailjr.
.Other r e l a t e d f a c t o r s a r e t h e handling c h a r a c t e r i s t i c s of a u r t r a n s p o r t
type a i r c r a f t i n day-to-day o p e r a t i o n s , t h e absence o r outage of: glide. slope
f a c i l i t i a s , cockpit proccdurcs, p o s s i b l e e f f e c t s of snow o r r a i n on dual
s t 2 t i c p o r t systens a s they could a f f e c t a l t i m e t r y accuracy, and a l t i t u d e
avarelics.6. These are a l l f a c t o r s which may e x i s t s i n g u l a r l y o r i n combina-.
t i o n . The i n a b i l i t y t o d e t e c t o r o b t a i n p o s i t i v e evidence, p a r t i c u l a r l y such
e v i d m c c as i c e ac.cret.ion o r moisture which becones l o s t i n wreckage, makes i t
d i f f i c u l t , LE n o t impossible, i n many c a s e s to reach conclusions based upon
s u b s t a n t i a l evidence. I t i s c l e a r t h a t had a l l ground and airborne navigat i o n a l systems beer, o p e r a t i n g a c c u r a t e l y & had t h e f l i g h t crews been p i l o t i n e
w i t h meticulous reference to properly i n d i c a t i n g f l i g h t instruments, t h e s e
a c c i d e n t s r~orildn o t have occurred.
In t h i s l i g h t , and with t h e number and frequency of approach and l n n d i i i g
phase accidents urid.zr s i m i l a r weather and o p e r a t i n g environaants, we b o l i eve
t h a t c e r t a i n ir:.:i-.u'iate a c c i d c n t prevcntion measures need t o be taken. W
e
believe. t h a t prelitxinary t o t h c s u c c e s s f u l completion of our i n v e s t i g a t i o n s
i n t o t h c f a c t o r s azd causcs of t h e r e c e n t rash of a c c i d e n t s , renewed a t k e n t i o n
t o , and mtpharts on recognized good p r a c t i c e s wi'l tend t o reduce t h e possib i l i t i e s of f u t u r e a c c i d e n t s .
--
P i l o t s , @perktors and t h e r e g u l a t o r y agencies should renew cn:?hasis on
an2 inq)zo;le sihcre\*cr p o s s i b l e
cockpit procedures, c r e v d i s c i p l i n e , and
f l i g h t r!2iIL1Sct1',ilt,
It is r c c o m x c n d d that bot!l tlie a i r carrier i n d v s t r y a1!;1
t h e FA4 revicw p o l i c i s s . procedures, p r a c t i c e s , and training toward incrc?.sin;
--
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62
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APPENDIX G
- 2 -
M r . David D. Thomas
crew e f f i c i e n c y and reducing d i s t r a c t i o n s and n o n e s s e n t i a l crew
f u n c t i o n s during t h e approach and landing phase of t h e f l i g h t . It i s
s p e c i f i c a l l y recoximanded t h a t crew f u n c t i o n s n o t d i r e c t l y r e l a t e d t o the
approach and l a n d i r ? , be reduced o r e l i m i n a t e d , c.specially during the l a s t
1000 f e e t of descent. Accomplishment of t h e in-range and landing check
l i s t s as f a r as p o s s i b l e i n advance of t h e l a s t 1,000-foot descent w i l l
allow f o r more i n t e n s e and perhaps more a c c u r a t e c r o s s checking and monitor. i n g of t h e descent through t h e s e c r i t i c a l a l t i t u d e s .
It is a l s o recommended t h a t d u r i n g t h e f i n a l approach one p i l o t maint a i n continuous v i g i l a n c e of f l i g h t instruments
i n s i d e t h e cockpit
u n t i l p o s i t i v e v i s u a l reference i s established.
-
-
I n o r d e r t o induce a renewed a l t i t u d e awareness during approaches where
less than f u l l p r e c i s i o n f a c i l i t i e s e x i s t , i t i s recomended t h a t t h e r e be
a requirement t h a t during t h e l a s t 1000' of f i n a l approach t h e p i l o t -not
I
f l y i n g c a l l out a J t i t u d e s i n 100-foot decrements above a i r p o r t e l e v a t i o n ( i n
a d d i t i o n t o a i r s p e e d and r a t e - o f - d e s c e n t ) .
To f u r t h e r enhance a l t i t u d e
awareness h i t h i n t h e c o c k p i t , i t i s reconmended t h a t t h e r e be a requirement
t o r e p o r t i n d i c a t e d a l t i t u d e t o A i r T r a f f i c Control a t v a r i o u s p o i n t s i n
t h e apprcach procedure such as t h e outbound procedure t u r n and a t t h e o u t e r
marker p o s i t i o n .
Consistent mith and i n support of t h e concept i n h e r e n t i n your R o t i c e
t h e Board urges t h e a v i a t i o n comnunity
t o consider e x p e d i t i n g dev2lopment and i n s t a l l a t i o n of a u d i b l e and v i s i b l e
a l t i t u d e warning devices 3nd t h e implementation of procedures f o r t h e i r u s e .
A d d i t i o n a l imqrovcments, although d e s i r a b l e now, are a t t a i n a b l e only through
continued r e s c a r c h and development.
of Proposed Rulecaking No. 67-53,
The reassessment of a l t i m e t r y systems w i t h p a r t i c u l a r regard t o t h e i r
s u s c e p t i b i l i t y t o i n s i d i o u s i n t e r f e r e n c e by forms of p r e c i p i t a t i o n needs t o
be t h e s u b j e c t of a t t e n t i o n by t h e h i g h e s t l e v e l of a e r o n a u t i c a l r e s e a r c h
f a c i l i t i e s and personnel. Toward t h i s end, we are meeting w i t h members of
your s t e . f f , t h e N a t i c n a l Aeronautics and Space Administration and various
segments of the a v i a t i o n comiunity t o i n i t i a t e an assessment of possible.
f a i l u r e modes and e f f e c t s w i t h i n t h e s t a t i c system.
-
The p o s s i b i l i t y of developzient of a d d i t i o n a l a l t i t u d e warning systems
e x t e r n a 1 , t o the a i r c r a f t -needs t o be cxplored by the a v i a t i o n comrmnity.
One such p o s s i b i l i t y would be a high i n t e n s i t y v i s u a l warning red l i g h t beam
p r o j e c t e d up along and s l i g h t l y belov the d e s i r e d approach g l i d e slope
t o warn of f l i g h t bn.low t h e d e s i r e d path.
-
Likewise, development is needed i n t h e f i e l d s of r a d i o / r a d a r , and
i n e r t i a l a l t i m e t r y and CltT/microviave p i c t o r i a l d i s p l a y approach a i d s as
p o s s i b l e improvcb replaccment of the baro:netric a l t i m e t r y system i n t h e ?near
future,
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63
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Mr. David D, Thomas
Modified use of e x i s t i n g approach r a d a r should be f u r t h e r s t u d i e d
w i t h regard t o i t s a d a p t a b i l i t y a s a surveillance--accident prevention-t o o l f o r n o n p r k c i s i m instrument approach.
During t h e t i m e t h a t w e p r e s s f o r answers as t o t h e causes of a number
of t h e s e r e c e n t a c c i d e n t s , t h e Board urges increased s u r v e i l l a n c e , more
frequent and more r i g o r o u s i n s p e c t i o n and maintenance of a l t i m e t r y systems
by both t h e a i r c a r r i e r o p e r a t o r s and t h e FAA; and urges, a l s o t h a t the FAA
reexamine c e r t i f i c a t i o n requirements and procedures t o determine i f t h e r e i s
a p o s s i b i l i t y of a s i n g l e f a i l u r e mode of nominally d u a l systems which,
when combined w i t h an a l r e a d y e x i s t e n t p a s s i v e f a i l u r e o r inadequate cockpit
procedures, can i n v a l i d a t e d u a l f a i l u r e p r o t e c t i o n f e a t u r e s .
Whereas t h e s e problems have been h i g h l i g h t e d by a i r carrier a c c i d e n t s ,
they should n o t be construed as being unique t o a i r c a r r i e r a v i a t i o n . The
S a f e t y Board considers t h a t they a r e a p p l i c a b l e t o a l l forms of a i r t r a n s por t a t i o n ..
We know t h a t your Administration, as well as o t h e r r e s p o n s i b l e segments
of t h e a v i a t i o n c m m n i t y , have been working e x t e n s i v e l y i n a l l of these
areas.
We appreciatje your coritinuing emphasis on t h e s a f e t y of a i r c a r r i e r
o p e r a t i o n s a s evigenced by r e c e n t communications with your i n s p e c t o r s and a i r l i n e management.
Your views regarding t h e iniplementaiion of our suggestions w i l l be
welcome.
S i n c e r e l y yours,
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DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
Honorable Joseph J. O'Connell, Jr.
Chairman, National T r a n s p o r t a t i o n S a f e t y Board
Department of T r a n s p o r t a t i o n
Washington, D.C. 20591
OFFICE OF
THE ADMINISTRATOR
Dear M r . Chairman:
I havc your letter of January 17, 1969, which contained suggestions and
recommendations f o r t h e prevention of a c c i d e n t s during t h e approach and
landing phase of f l i g h t .
My l e t t e r of January 28, 1969, commented on a number of t h e items covered
in your January 17 letter. Therefore, I w i l l n o t r e p e a t them here, except
t o reiterate t h a t our immediate concern and followup a c t i o n s are d i r e c t e d
t o t h e areas of adherence t o e s t a b l i s h e d procedures, a l t i t u d e awareness,
w i n t e r o p e r a t i n g procedures, and cockpit d i s c i p l i n e and v i g i l a n c e .
Our comments concerning t h e matters discussed i n your l d t t e r are as follows:
1. Reduce d i s t r a c t i o n s and non-essential crew f u n c t i o n s during approach
and landinp. I n s t r u c t i o n s t o our i n s p e c t o r s r e q u i r e them t o review on a
continuing b a s i s cockpit check lists and procedures t o assure t h a t minimum
checking w i l l be done during t h e more critical periods of f l i g h t such as
departures, approaches, and landings.
2. Use of in-ranpe and landing check lists. We b e l i e v e t h e a i r l i n e s
r e q u i r e a l l cockpit check procedures, p a r t i c u l a r l y t h e in-range check list,
t o - b e completed well b e f o r e t h e last 1,000 f e e t of descent. However, we
w i l l request our i n s p e c t o r s t o doublecheck and t a k e a c t i o n where warranted.
3.
Cockpit v i g i l a n c e . The i n s t r u c t i o n s t o our i n s p e c t o r s r e f e r r e d t o i n
item 1 above a l s o r e q u i r e them t o a s s u r e t h a t cockpit check procedures are
arranged so t h a t t h e p i l o t f l y i n g devotes f u l l a t t e n t i o n t o f l i g h t instruments.
As s t a t e d i n my l e t t e r of January 28, 1969, crew v i g i l a n c e and cockpit
d i s c i p l i n e i s one of t h e areas s t r e s s e d i n my wire t o t h e a i r l i n e presidents.
4, A l t i t u d e awareness.
Over two and one-half
(2%) y e a r s ago, i n s t r u c t i o n s
were issued t o o u r i n s p e c t o r s t o be s u r e t h e a i r l i n e s emphasized i n t r a i n i n g
and included i n company manuals a l t i t u d e awareness procedures t o be used
d u r i n g climbs, descents, and instrument approaches. This is one of t h e
areas on which we asked our i n s p e c t o r s t o place emphasis during t h e
a c c e l e r a t e d i n s p e c t i o n s mentioned i n my January 28 letter.
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2
Your l e t t e r recommended t h a t during t h e last 1,000 f e e t of t h e f i n a l
approach the p i l o t not f l y i n g be required t o c a l l out a l t i t u d e s i n 100
foot increments. The a l t i t u d e awareness procedures t h a t we have asked
t h e carriers t o adopt r e q u i r e the p i l o t not f l y i n g t o c a l l out, during
t h e f i n a l 1,000 f e e t of the approach, 500 f e e t above f i e l d elevation,
100 f e e t above minimums, and minimums. We believe t h i s procedure i s
preferable, s i n c e it serves t o keep cockpit conversation t o a minimum
and a t t h e same t i m e , a s s u r e s p i l o t a l t i t u d e awareness. This procedure
a l s o reduces p i l o t workload.
5 . P i l o t r e p o r t s t o ATC of a l t i t u d e s during instrument approaches.
Adoption of t h i s suggestion would s i g n i f i c a n t l y i n c r e a s e frequency congestion
e b e l i e v e our e f f o r t s i n the
and increase crew and c o n t r o l l e r workload. W
areas of p i l o t t r a i n i n g and education w i l l prove t o be t h e most b e n e f i c i a l
course of action.
6 . A l t i t u d e a l e r t i n g devices. I appreciate your support of t h e r u l e which
became e f f e c t i v e on September 28, 1968, which w i l l r e q u i r e by February 28,
1971, both v i s u a l and a u r a l a l t i t u d e a l e r t i n g s i g n a l s t o warn p i l o t s of
j e t a i r c r a f t when approaching s e l e c t e d a l t i t u d e s during climbs, descents,
and instrument approaches.
7. A l t i m e t r y systems. With r e s p e c t t o your suggestion t h a t an assessment
be made of possible f a i l u r e modes of altimeter s t a t i c systems, we plan t o
p a r t i c i p a t e with NASA and t h e a v i a t i o n industry t o assist i n such a program.
Development and t e s t i n g t o v a l i d a t e such improvements w i l l be required.
A t t h i s t i m e , we know of no p r a c t i c a l replacement f o r t h e barometric
altimeter.
8. Additional a l t i t u d e warninp systems. Your suggestion concerning v i s u a l
g l i d e path warning would not provide complete information concerning t h e
optimum g l i d e path as does t h e Visual Approach Slope I n d i c a t o r (VASI) systems
which are i n s t a l l e d a t many runways throughout the country. We plan t o
continue t o i n s t a l l these systems i n accordance with c u r r e n t criteria
within t h e l i m i t s of funds appropriated f o r t h i s purpose.
9 . Development t o replace barometric altimeter systems. The use of i n e r t i a l
a l t i m e t r y could be i n v e s t i g a t e d , but must be considered as a long range R&D
program. CRT/microwave p i c t o r i a l d i s p l a y (radar mapping) has been evaluated
by t h e m i l i t a r y as an a d d i t i o n a l approach a i d monitor. The FAA as y e t does
not have d e t a i l e d information, s i n c e t h i s equipment, u n t i l recently, was
c l a s s i f i e d , However, we plan t o o b t a i n a d d i t i o n a l information and w i l l
look i n t o t h e matter f u r t h e r .
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3
10, Modified use of e x i s t i n g approach r a d a r , I would a p p r e c i a t e r e c e i v i n g
from you a d d i t i o n a l d e t a i l s on t h e modified use you had i n mind, so t h a t
we can more properly e v a l u a t e and respond t o your suggestion.
11. I n s p e c t i o n and maintenance of altimeter systems. On January 2 9 , 1969,
r e p r e s e n t a t i v e s of our F l i g h t Standards S e r v i c e met with ATA's Engineering
and Maintenance Advisory Committee t o review and d i s c u s s altimetry problems,
The a i r l i n e s are monitoring t h e o p e r a t i o n of t h e s e systems and reviewing
t h e i r maintenance procedures, ATA advised us at t h i s meeting t h a t few
t r o u b l e s are being experienced o r r e p o r t e d by t h e f l i g h t crews. This is
confirmed by our a n a l y s i s of t h e MRR r e p o r t s . Nevertheless, ATA has agreed
t o r e a c t i v a t e i t s Altimetry and S t a t i c System Maintenance Subcommittee t o
f u r t h e r explore t h i s area and i n t e n d s t o review and update material previously
published on t h i s subject.
12. C e r t i f i c a t i o n of altimeter systems. On August 16, 1968, we issued a
Notice of Proposed Rule Making proposing r e v i s i o n s t o P a r t 25 of the Federal
Aviation Regulations t o r e q u i r e i n systems design means t o a s s u r e continued
s a f e o p e r a t i o n following any s i n g l e f a i l u r e or combination of f a i l u r e s n o t
shown t o be extremely improbable. I n d u s t r y comments are now being reviewed
and analyzed.
Your i n t e r e s t i n t h e s e problems is appreciated and I can a s s u r e you we w i l l
continue t o p r e s s f o r s o l u t i o n s t o them.
I
D. D. Thomas
Act i ng Admi n i s tr a tor
NATIONAL MSPORTATION SAFETY BOARD
WASHINGTON, D. C. 20591
MTRACT FROM AIRCRAFT ACCIDENT REPORT
SOUI'HEBN AIRWAYS, I N C
D O U G ~ SDC- 9- 15, ~ 9 2 s
GULFPORT, MISSISSIPPI
FEBRUARY 17, 1971
REPORT NUMBER:
NPSB-AAR-71-14
RECOMMEXDATIONS
The Board fiinds t h a t a l t i t u d e a l e r t i n g equipnent now i n s t a l l e d on
air c a r r i e r a i r c r a f t i s not used as a ground proximity warning device
which has been previously recommended and, t h e r e f o r e , t h e Board recommends t h a t t h e Federal: Aviation Administration:
1. Develop a ground proximity warning system f o r use i n t h e
approach and landing phases of operation which w i l l warn
f l i g h t c r e w s of excessive r a t e s of descent, unwanted/inadv e r t e n t descent below Minimum Descent A l t i t u d e s , o r
descent through Decision Height. It would be d e s i r a b l e
i f t h e equipment now i n s t a l l e d could meet t h i s need; and
2. Develop and implement a p p r o p r i a t e o p e r a t i o n a l procedures
t o provide t h i s type of warning t o f l i g h t c r e w s for use
during t h e approach and landing phase of f l i g h t .
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DEPARTMENT OF TRANSPORTATIOF
APPENDIX G
FEDERAL AVIATION ADMINISTRATION
1 5 NOV 1971
OFFICE OF
THE ADMINISTRATOR
Honorable John 8. Beed
Chairman, National T r a n s p o r t a t i o n
Safety Board
Department of T r a n s p o r t a t i o n
Washington, I). C. 20591
Dear Mr. Chairman:
Thio is I n raeponee t o tbe t e c o m e n d e t i o n s contained i n Report Nunbor
NT~P-1blR-71-14, an a i r c r o f t a c c i d e n t report concerning a Southern
Airway8 DC-9 a t Gulfport, Missiasippi, on 17 February 1971 and r e f e r r e d
t o in your 1 o t t e r ; d a t e d 3 November 1971.
With r e e p e c t t o the rocanmotadation t o develop a ground proximity warning
systen f o r use durixq approach and landing, we believe the present
instrumentation and pxocedure~tare s a f e and adequate. This preeupposes proper cockpit Jiociplines are cwintained. On t h i s f l i g h t
t h e Captain s t a t e d that d u r i w tho epproach ha read the altimeter
a t 300 f e e t . The voica r e c o r d e r t r a n s c r i p t shows the Captain
c a l l e d 150 f e e t and advised the c o p i l o t who wag flying t h e a i r c r a f t
t o "bring It up."
The report brings out that the radar altimeter was
s e t f o r 400 f e e t a d tho yellow warning l i g h t waa observed by the p i l o t .
We b e l i e v e t h e p i l o t was w e l l aware that he w a s below t h e Minimum Descent
A l t i t u d e (IDA). We f a i l to 8ee has a ground proximity warnis could
have contributed furthr to w h a t we believe was already known.
We are, however, r e a s s e s s i n g our syatem requirements f o r nonprecision
atr8ight-in-appmach syatems w i t h a view t o providing additional
a s e l s t a n c e t o the p i l o t in the form of accurate p o s i t i o n information
which w i l l make his e v a l u a t i o n of the visual approach segment less
s u s c e p t i b l e t o hupraa error.
W i t h respect t o the recomaendation t o have o p e r a t i o n a l procedures t o
provide ground proximity warning, t h e agency has, f o r any years,
had an a l t i t u d e awareness program. Operators develop and publish
ln their manuals caapany procedures to i n s u r e altitude awareness during
approaches. Southern Mnaays d i d have such a procedure, but it was not
followed d u r i n g the approach in question. Additionally, as t h e m n p r e c i s i o n
8traight-in-approach syetenr is r e v i s e d we w i l l conaidor new o r a d d i t i o n a l
procedures t o iprplcrppsat the systea.
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APPENDIX G
W i t h reapcct t o the recolzPnradaClon t o comnaiselon the f u l l XLS a t
Gulfport, grading nacded t o rolve the Biting problem i a being
aceqliahed by the oponoor. We elcpscrt the e y s t w t o be
C O d 8 8 i O X m d Fn early 1972.
(sigr'ed)K. M. smith,
Acting Admiristratof
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DEPARTMENT OF TRANSPORTATION
=DERAI.
AVIATION ADMINISTRATION
1 5 MAR 1972
Honorable John H. Reed
Chairman, National T r a n s p o r t a t i o n S a f e t y Board
Department of T r a n s p o r t a t i o n
OFFICE OF
THE ADMINISTRATOR
Dear Mr.
This is i n response t o t h e recommendations contained i n your Report
Number AAR-72-4, a n a i r c r a f t i n c i d e n t r e p o r t , involving a Northeast
A i r l i n e s , Inc., DC-9 a t Martha's Vineyard, Massachusetts, on 22 June
1971.
As you state t h e s e recommendations p a r a l l e l those regarding t h e
Southern Airwavs DC-9 a c c i d e n t a t Gulfport, Mississippi. Our p o s i t i o n
i n t h i s renard is t h e same as s t a t e d i n our l e t t e r of 15 November 1971
concerning t h e Gulfport accident. W e b e l i e v e t h a t c u r r e n t instrumentation
and procedures a r e s a f e and adequate assuming t h a t proper cockpit d i s c i p l i n e s are maintained. I n t h i s i n c i d e n t , as i n t h e Southern a c c i d e n t ,
according t o your r e p o r t s t h e company a l t i t u d e awareness and c a l l o u t
procedures f o r nonprecision approaches were not followed. Thus, i t
appears t h a t i f t h e s e procedures had been followed, t h e i n c i d e n t would
not have happened.
Nevertheless, we have reassessed our system requirements f o r s t r a i g h t i n nonprecision approaches and are developing new c r i t e r i a which w e
propose t o be a p p l i e d t o t h e s e type approaches. One c r i t e r i o n which we
are working on involves e s t a b l i s h i n g a f i n a l approach descent f i x such
as a f a n marker or o t h e r s u i t a b l e f a c i l i t y f o r each s t r a i g h t - i n nonp r e c i s i o n approach procedure. This descent f i x would be located a t a
p o i n t on t h e f i n a l approach from which a n o m 1 descent path of approximately 3O from MDA t o touchdown can be commenced, provided t h e required
v i s u a l r e f e r e n c e is e s t a b l i s h e d . The p i l o t would be required t o maintain
a n a l t i t u d e a t o r above t h e MDA u n t i l passing t h e descent f i x . Another
c r i t e r i o n which we propose will be t o provide VAS1 f o r each runway served
by t h i s type approach. The VAS1 w i l l provide v i s u a l v e r t i c a l guidance
a t normal descent rates f o r t h e v i s u a l segment of t h e approach. These
new c r i t e r i a should r e s u l t i n a g r e a t e r degree of a l t i t u d e awareness
throughout t h e procedure.
Sincere 1y ,
W.S. GOVERNMENT PRINTING OFFICE: 1972 721-491/750 1-3
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