DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
This training is extracted from a presentation by Orrin "Kurt" Anderson, an Air
Safety Investigator with the National Transportation Safety Board. The
presentation was given in the Puget Sound area, sometime around 2003 (my best
guess). Mr. Anderson has investigated a very large number of general aviation
accidents that involved density altitude as one of the causal factors. This
presentation describes a number of things, all involving to some degree density
altitude, that pilots should, but often don't know.
Although most of his examples involve flying in the mountainous areas of the
Pacific Northwest, the lessons are certainly applicable to pilots across the country.
This training is presented on 27 pages, each consisting of Mr. Anderson's audio
narrative, and the accompanying text or graphic.
Navigation controls are located at the top of the screen. Pressing the left arrow or
right arrow will take you back for forward one slide.
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Nine Deadly Sins
•
•
•
•
•
•
•
•
•
Turn diameter
Induced power requirement
Best position in a canyon
Landing ground speed
How to figure real takeoff performance
How to adjust Vy and Vx
What flap position to use
Climb gradient
When to use short/soft/obstacle clearance takeoffs
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
Density Altitude Accident Videos
Unfortunately, I was unable to locate two of the videos that Mr. Anderson mentions in
his presentation. However, I have substituted another video (Cameron Park) in which
density altitude seems to a contributing factor.
•
Cameron Park (in place of the Cessna 172 in the box canyon).
•
L-19 accident. This is the one described by Mr. Anderson.
After he completes his narration, go on to the next slide to see the videos.
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The First Deadly Sin : Not Knowing Your Turn Diameter
At 8,000 Feet
95 Degrees
150 Indicated Air Speed
At Sea Level
True Air Speed = 180
55 Degrees
150 Indicated Air Speed
True Air Speed = 150
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The First Deadly Sin : Not Knowing Your Turn Diameter
•
•
•
•
The turn radius depends on the aircraft's speed and the bank angle.
Turn Radius = V 2 / 11.26 tan Phi
Where V is the aircraft velocity (True Airspeed)
Phi is the Bank Angle
•
•
•
•
In the examples, the Bank Angle is assumed to be 45 degrees.
The tangent of 45 degrees = 1
So, the equation is simplified to:
Turn Radius = V 2 / 11.26
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The First Deadly Sin : Not Knowing Your Turn Diameter
•
•
Turn Radius = V2/ 11.26
(When bank angle = 45 degrees)
•
•
•
For 150 (knots or MPH)
r = 1502 / 11.26
r = 1,998 feet
•
•
•
For 180 (knots or MPH)
r = 1802 / 11.26
r = 3,240 feet
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The First Deadly Sin : Not Knowing Your Turn Diameter
•
Turn Radius at Sea Level = 1,998 Feet
•
Turn Radius at 8,000 Feet = 3,240 Feet
•
(When bank angle = 45 degrees)
•
But, Radius is only half of the distance!
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The First Deadly Sin : Not Knowing Your Turn Diameter
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The First Deadly Sin : Not Knowing Your Turn Diameter
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Second Deadly Sin : Not Knowing Your Induced Power
Requirement
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Second Deadly Sin : Not Knowing Your Induced Power
Requirement
Bank Angle
Load Factor
Percent Increase in
Induced Drag from
Level Flight
0
1.000
0
15
1.036
7.2
30
1.154
33.3
45
1.414
100
60
2.00
300
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Second Deadly Sin : Not Knowing Your Induced Power
Requirement
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Second Deadly Sin : Not Knowing Your Induced Power
Requirement
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Second Deadly Sin : Not Knowing Your Induced Power
Requirement
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Second Deadly Sin : Not Knowing Your Induced Power
Requirement
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Third Deadly Sin: Not Knowing Your Best Position
In A Canyon
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Fourth Deadly Sin: Not Knowing Your Landing
Ground Speed
8,000 Feet at 95 Degrees
Variable Winds 10G18
Recommended Speed: 70 - 75 MPH
75 Indicated = 90 True Air Speed
??? Add 1/2 of Gust (18 MPH) ???
1/2 of 18 = 9 = 11 True Air Speed
90 + 11 = 101 MPH
Over the Threshold at 101 MPH
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Fifth Deadly Sin: Not Knowing How to Compute Real
Takeoff Performance
At Sea Level & 59°
At 2500 ft. & 50°
At 5000 ft. & 41°
At 7500 ft. & 32°
Gross
Weight
Pounds
IAS at
50' MPH
Head
Wind
Knots
Ground
Run
Total to
clear 50
ft obs.
Ground
Run
Total to
clear 50
ft obs.
Ground
Run
Total to
clear 50
ft obs.
Ground
Run
Total to
clear 50
ft obs.
2300
68
0
865
1525
1040
1910
1255
2480
1565
3855
10
615
1170
750
1485
920
1955
1160
3110
20
405
850
505
1100
630
1480
810
2425
0
630
1095
755
1325
905
1625
1120
2155
10
435
820
530
1005
645
1250
810
1685
20
275
580
340
720
425
910
595
1255
0
435
780
520
920
625
1095
765
1370
10
290
570
355
680
430
820
535
1040
20
175
385
215
470
270
575
345
745
2000
1700
63
58
NOTE 1: Increase distance 10% for each 25° F above standard temperature for particular altitude.
NOTE 2: For operation on a dry, grass runway, increase distances (both "ground run" and "total to clear 50 ft. obstacle") by
7% of the "total to clear 50 ft. obstacle" figure.
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Fifth Deadly Sin: Not Knowing How to Compute Real
Takeoff Performance
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Sixth Deadly Sin: Not Knowing How to Adjust Vy and Vx
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Sixth Deadly Sin: Not Knowing How to Adjust Vy and Vx
The actual charts to which Mr. Anderson refers were not available. However, you can see the same relationships between
altitude, weight, and IAS for best rate of climb from this chart, which is for a typical light aircraft.
Maximum Rate-Of-Climb Data
At Sea Level & 59° F
At 5,000 ft. & 41° F
At 10,000 ft. & 23° F
At 15,000 ft. & 5° F
GW
IAS
MPH
Rate of
climb
Gal. of
fuel
used
IAS
MPH
Rate of
climb
Fuel
used
from SL
IAS
MPH
Rate of
climb
Fuel
used
from SL
IAS
MPH
Rate of
climb
Fuel
used
from SL
2300
82
645
1.0
81
435
2.6
79
230
4.8
78
22
11.5
2000
79
840
1.0
78
610
2.2
76
380
3.6
75
155
6.3
1700
77
1085
1.0
76
825
1.9
73
570
2.9
72
315
4.4
Note1: Flaps up, full throttle, mixture leaned for smooth operation above 3000 ft.
Note2: Fuel used includes warm up and take-off allowance.
Note3: For hot weather, decrease rate of climb 20 ft./min. for each 10° F above standard day temperature for particular altitude.
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Seventh Deadly Sin: Not Knowing What Flap Position to Use
Item
Altitude
Flaps
Outside Air Temperature
0° F
20° F
40° F
60° F
80° F
100° F
40°
Landing Distance * (Ft.)
Sea Level
1035
1070
1110
1145
1180
1215
40°
To land over 50 ft. obstacle
at 67 MPH TIAS approach
(Roll 40% distance shown)
2000 ft
1100
1140
1175
1210
1245
1280
4000 ft
1165
1205
1240
1280
1315
1415
6000 ft
1235
1270
1310
1345
1380
1415
7000 ft
1270
1305
1345
1380
1415
1450
40°
40°
40°
UP
Take-off Distance * (Ft.)
Sea Level
1460
1580
1700
1820
1930
2050
UP
To clear 50 ft. obstacle at
76 MPH TIAS (Ground run
approximately 40%
distance shown)
2000 ft
1780
1910
2050
2190
2340
2500
4000 ft
2140
2290
2450
2610
2790
3000
6000 ft
2550
2740
2930
3140
3360
3620
7000 ft
2820
3040
3260
3500
3750
4040
UP
UP
UP
20°
Take-off Distance * (Ft.)
Sea Level
1230
1350
1480
1625
1795
1995
20°
To clear 50 ft. obstacle at
67MPH TIAS (Ground run
approximately 40%
distance shown)
2000 ft
1540
1600
1860
2050
2250
2350
4000 ft
1920
2110
2340
2580
2855
3140
6000 ft
2450
2720
3000
3300
3620
3990
7000 ft
2780
3100
3420
3735
4080
4455
89
Sea Level
760
740
715
690
670
345
86
2000 ft
670
645
625
600
580
555
84
4000 ft
580
555
535
510
485
465
81
6000 ft
490
365
440
420
395
370
370
345
325
20°
20°
20°
UP
UP
UP
UP
UP
Norm
al
Rate
of
Climb
FPM
Best
Climb
Speed
TIAS
79
7000 ft
Copyright
© 2012
David R. Hunter
445
420
395
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Eighth Deadly Sin: Not Knowing Your Climb Gradient
8,000 Feet & 95 Degrees
90 MPH (108 True)
200 Ft/Min
111 Ft/Mile
4.5 miles to 500 feet
8,000 Feet & 95 Degrees
80 MPH (96 True)
200 Ft/Min.
125 Ft/Mile
Sea Level @ 55 Degrees
90 MPH
700 Ft/Min.
466 Ft/Mile
4.0 miles to 500 feet
1.07 miles to 500 feet.
Copyright © 2012 David R. Hunter
(9 miles to pattern altitude)
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
The Ninth Deadly Sin: Not Knowing When to Use Short-SoftObstacle Clearance Takeoffs
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
Conclusion
1. Turn diameter
2. Induced power requirement
3. Best position in a canyon
4. Landing ground speed
5. How to figure real takeoff performance
6. How to adjust Vy and Vx
7. What flap position to use
8. Climb gradient
9. When to use short/soft/obstacle clearance takeoffs
Copyright © 2012 David R. Hunter
DENSITY ALTITUDE: THE NINE DEADLY SINS
WHAT PILOTS DON’T KNOW THAT WILL KILL THEM
THE END
I hope you found this presentation interesting, and that it makes
you a more proficient, safer pilot.
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Copyright © 2012 David R. Hunter