Rules of thumb
General Briefing G2
AIRLINE TRAINING CENTER, INC.
V2.0
Content – G2
 1 in 60 rule
 Speed factor, ground factor, air factor
 Rate of descent, angle of descent,
descent gradient
 Rate of climb, angle of climb, climb
gradient
 Descent planning
 Wind and time corrections
AIRLINE TRAINING CENTER, INC.
Content – G2
 1 in 60 rule
 Speed factor, ground factor, air factor
 Rate of descent, angle of descent,
descent gradient
 Rate of climb, angle of climb, climb
gradient
 Descent planning
 Wind and time corrections
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Mathematics
Most angles are defined in degrees, but you can define an angle
also in radians (rad).
For an angle of one radian the arc length along the edge of the
circle is equal in length to the radius.
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Mathematics
Circumference of a circle = 2 x π x r
2 x π (6,28) radii in the circumference of a circle
2 x π radians in a circle, in 360°
Conclusion: 1 rad = 360° / 2 x π = 57,3° ≈ 60°
≈ 60°
AIRLINE TRAINING CENTER, INC.
r
1 in 60 rule
• Mathematics
1 rad ≈ 60° with arc length = radius
For an angle of 1°, arc length ≈ radius / 60
1°
r / 60
r
not to scale
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• The 1 in 60 rule
1 NM ≈ 6000ft
1°
60 NM
≈ 100ft
1°
1 NM
≈ 300ft
Standard ILS
3°
1 NM
AIRLINE TRAINING CENTER, INC.
not to scale
1 in 60 rule
• Exercises
B
α
A
• at 60 NM, 3°  B ≈ … NM ?
• at 60 NM, 2 NM off  α ≈ ?
• at 15 NM, 5°  B ≈ … NM ?
• at 12 NM, 4 NM off  α ≈ ?
• at 25 NM, 2°  B ≈ … NM ?
• at 20 NM, 6 NM off  α ≈ ?
• at 1 NM, 3°  B ≈ … ft ?
• at 1 NM, 200ft off  α ≈ ?
• at 10 NM, 3°  B ≈ … ft ?
• at 5 NM, 2000ft off  α ≈ ?
• at 5 NM, 4°  B ≈ … ft ?
• at 6 NM, 1800ft off  α ≈ ?
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
B
α
A
• at 60 NM, 3°  B ≈ 3 NM
• at 60 NM, 2 NM off  α ≈ 2°
• at 15 NM, 5°  B ≈ 1,25 NM
• at 12 NM, 4 NM off  α ≈ 20°
• at 25 NM, 2°  B ≈ 0,8 NM
• at 20 NM, 6 NM off  α ≈ 18°
• at 1 NM, 3°  B ≈ 300 ft
• at 1 NM, 200ft off  α ≈ 2°
• at 10 NM, 3°  B ≈ 3000 ft
• at 5 NM, 2000ft off  α ≈ 4°
• at 5 NM, 4°  B ≈ 2000 ft
• at 6 NM, 1800ft off  α ≈ 3°
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. You are on a VFR navigation, flying a leg from point A to point
B (distance 20 NM). Halfway between A and B you verify your
position with a landmark and with the chart you notice that you
drifted 2 NM off track. What is your drift angle?
drift angle ≈ 12°
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. You are on a VFR navigation, flying a leg from point D to point
E (distance 35 NM) at 120kts. 6 minutes after passing point D,
you verify your position with a landmark and with the chart you
notice that you drifted 3 NM off track. What is your drift angle?
drift angle ≈ 15°
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. Airport elevation is 1500ft, mountain ridge (top 5500ft) at 20NM
from airport. What minimum angle do we need to pass the ridge
without any margin?
5500ft
minimum angle ≈ 2°
1500ft
20NM
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. 2 NM after the departure end of the runway is a building
extending up to 400ft. You pass the end of the runway at 100ft
during your take-off. What angle of climb do we need to pass the
building with at least 500ft clearance?
required angle = 4°
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. We want to follow a 3° descent path from 12500ft to 2500ft.
How many miles do we need to descent to 2500ft.
33 NM
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. How many nautical miles is the green segment of this DME arc?
Procedure is flown at 120 KTAS.
12DME arc
turn radius = TAS/200
7,4 NM
R090
Arc distance between R050 and R090 = 8.0NM
Turn radius = 0.6NM
Green segment = 8.0 – 0.6 = 7.4 NM
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. At which altitude approximately should you start the descent
at the FAF arriving via FLORA?
≈ 2920 ft
Distance threshold to FAF = 8.8NM ≈ 9NM
1 in 60 rule: 9NM with a 3° ≈ 2700ft
2700ft + TCH (≈60ft) + apt. elev. (≈160ft)
AIRLINE TRAINING CENTER, INC.
1 in 60 rule
• Exercises
Q. At which altitude should you cross 2.5DME ILST?
≈ 1425 ft
AIRLINE TRAINING CENTER, INC.
Content – G2
 1 in 60 rule
 Speed factor, ground factor, air factor
 Rate of descent, angle of descent,
descent gradient
 Rate of climb, angle of climb, climb
gradient
 Descent planning
 Wind and time corrections
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Definitions
Speed factor is a general term indicating the distance travelled
per minute, expressed in nautical miles per minute. Sometimes
the term speednumber is used instead of speed factor.
Ground factor (GF) is the ground distance (ground miles)
travelled per minute.
GS
GF 
60
Air factor (AF) is the air distance (air miles) travelled per minute.
TAS
AF 
60
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Air factor
Another good approximation for air factor is:
Mach number x 10
Most of the times this equation can be used on bigger airplanes
where Mach is indicated on the flightdeck.
air factor ≈ ?6 NM/min
example
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. Calculate the air factor for the given TAS / Mach number?
• 90 KTAS  AF = ?
• M .78  AF ≈ ? (A320)
• 120 KTAS  AF = ?
• M .84  AF ≈ ? (B747)
• 150 KTAS  AF = ?
• M .72  AF ≈ ? (AVRO RJ)
• 180 KTAS  AF = ?
• 100 KTAS  AF = ?
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. Calculate the air factor for the given TAS / Mach number?
• 90 KTAS  AF = 1,5 NM/min
• M .78  AF ≈ 8 NM/min
• 120 KTAS  AF = 2 NM/min
• M .84  AF ≈ 8,5 NM/min
• 150 KTAS  AF = 2,5 NM/min
• M .72  AF ≈ 7 NM/min
• 180 KTAS  AF = 3 NM/min
• 100 KTAS  AF ≈ 1,7 NM/min
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. Calculate the ground factor for the given TAS and wind?
• 120 KTAS, 20kts HW  GF ≈ ?
• 105 KTAS, 15kts TW  GF = ?
• 130 KTAS, 25 kts TW  GF ≈ ?
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. Calculate the ground factor for the given TAS and wind?
• 120 KTAS, 20kts HW  GF ≈ 1,7 NM/min
• 105 KTAS, 15kts TW  GF = 2 NM/min
• 130 KTAS, 25 kts TW  GF ≈ 2,5 NM/min
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Navigation exercises:
AIRLINE TRAINING CENTER, INC.
• AB
− leg distance: 30 NM
− 110 KTAS
− TW 15 kts
− ETE
?
15 min
• BC
− leg distance: 50 NM
− 120 KTAS
− TW 25 kts
− ETE
?
20 min
Speed factor, ground factor, air factor
• Exercises
Navigation exercises:
AIRLINE TRAINING CENTER, INC.
• C  D diversion
− leg distance: 45 NM
− 145 KTAS
− HW 20 kts
− ETE
?
22 min
• C  E diversion
− leg distance: 70 NM
− 140 KTAS
− HW 30 kts
− ETE
?
35 min
Speed factor, ground factor, air factor
• Exercises
IFR navigation exercises:
• Under radar vectors to final on base leg. Speed 120 KTAS,
HW 15 kts. How much time left before intercepting final?
3,5 min
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
IFR navigation exercises:
• Under radar vectors to final on base leg. Speed 100 KTAS,
TW 10 kts. How much time left before intercepting final?
2 min
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. ATC request ETA overhead point EXIBA, distance to EXIBA is
80 NM. Speed 145 KTAS, HW 20 kts.
13:45
14:25
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. ATC request ETA overhead point DOBAL, distance to DOBAL
is 30 NM. Speed 110 KTAS, HW 20 kts.
16:32
16:52
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. What is you air factor, ground factor and at what time will you
arrive overhead TILLE?
AF ≈ 4 NM/min
GF ≈ 3 NM/min
TILLE @ 11:37Z
AIRLINE TRAINING CENTER, INC.
Content – G2
 1 in 60 rule
 Speed factor, ground factor, air factor
 Rate of descent, angle of descent,
descent gradient
 Rate of climb, angle of climb, climb
gradient
 Descent planning
 Wind and time corrections
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Mathematics - AoD
Y

X
For small angles tan(α) ≈ α (with α expressed in radians)
Y
tan  [rad ]   [rad ] 
X
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Mathematics - AoD
altitude ft 

distance NM 
altitude [ft]
tan  [rad ]   [rad ] 
distance [ft]
 [rad ] 
AIRLINE TRAINING CENTER, INC.
altitude [ft]
distance [NM]  6000
Rate of descent, angle of descent,
descent gradient
• Mathematics - AoD
 [rad ] 
 []
altitude [ft]
distance[NM]  6000

altitude [ft]
distance[NM]  6000
 [] 
altitude [ft]
distance[NM] 100
60
altitude [FL] 100
 [] 
distance[NM] 100
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Mathematics - AoD
altitude ft 

distance NM 
altitude [FL] 100
 [] 
distance[NM] 100
FL
 [] 
distance[NM]
AIRLINE TRAINING CENTER, INC.
≈ angle of descent [ ° ]
Rate of descent, angle of descent,
descent gradient
• Mathematics - RoD
RoD [ft/min]
AoD[]
GS NM / hr 
FL
AoD[] 
distance[NM]
RoD[FL/hr]
AoD[] 
GS[NM/hr]
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Mathematics - RoD
RoD[FL/hr]
AoD[] 
GS[NM/hr]
60
RoD[ft/min] 
100
AoD[] 
GS[NM/hr]
100
RoD[ft/min]  AoD[]  GS[kts]
60
RoD[ft/min
Rate of descent
[ ft/min] ]  AoD[]  GF[NM/min]100
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Descent gradient
descent gradient [%]
 AoD 2  1
3° ≈ ?5 %
4° ≈ ?7 %
example
Rate of descent [fpm]
AIRLINE TRAINING CENTER, INC.
≈ descent gradient [%] x GS
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. Calculate angle of descent, descent gradient and rate of
descent?
Altitude to loose
2000ft
3000ft
1200ft
in distance of
6 NM
5 NM
3 NM
with GS
120 kts
100 kts
150 kts
AoD
?
?
?
descent gradient
?
?
?
RoD
?
?
?
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. Calculate angle of descent, descent gradient and rate of
descent?
Altitude to loose
2000ft
3000ft
1200ft
in distance of
6 NM
5 NM
3 NM
with GS
120 kts
100 kts
150 kts
AoD
3,5°
6°
4°
descent gradient
6%
11%
7%
RoD
720 fpm
1100 fpm
1050fpm
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. You are flying enroute at 11.000ft, ATC requests you to
descent and reach waypoint TANGO at 5000ft. TANGO is at 12
NM and your groundspeed is 160 kts. What rate of descent will
you need?
RoD ≈ 1300 fpm
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. What AoD and RoD do we need to fly to pass the step down
fix at 12.0 NM and 7.0 NM at the minimum altitude? What will be
our final RoD (from
to the touchdown point)? GS is 90kts.
6200ft
5000ft
4000ft
AoD ≈ 2°
AoD ≈ 4°
RoD ≈ 300 fpmRoD ≈ 600 fpm
Final RoD ≈ 450 + 100fpm
1900ft
AIRLINE TRAINING CENTER, INC.
7.0
12.0
15.0
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. What is the AoD and RoD required to reach the stepdown
fixes at the minimum altitudes? GS is 75 kts.
KCHD, VOR Rwy 4R
4°
500 fpm
AIRLINE TRAINING CENTER, INC.
3°
375 fpm
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. What is the final RoD required to the MDA? GS is 75 kts.
KSDL, VOR A
450 + 200 fpm
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. What RoD is required to stay on the glide of a standard ILS
approach, at 90 – 100 – 120 – 150 kts GS?
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. Airport elevation is 2500ft, mountain ridge at 30 NM from the
airport with a top of 8000ft. What RoC and AoC do we need to
clear the top of the mountain with 1000ft clearance at 90KIAS
(no wind)?
8000ft
2°
300 fpm
2500ft
30NM
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. What is the angle of descent and rate of descent required to
follow the published final approach?
AoD ≈ 4°
RoD ≈ 800 fpm
AIRLINE TRAINING CENTER, INC.
Rate of descent, angle of descent,
descent gradient
• Exercises
Q. What is the descent gradient and required rate of descent of
this non-precision approach?
Descent grad. ≈ 6%
RoD ≈ 540 fpm
AIRLINE TRAINING CENTER, INC.
Content – G2
 1 in 60 rule
 Speed factor, ground factor, air factor
 Rate of descent, angle of descent,
descent gradient
 Rate of climb, angle of climb, climb
gradient
 Descent planning
 Wind and time corrections
AIRLINE TRAINING CENTER, INC.
Rate of climb, angle of climb,
climb gradient
• thumbrules
Same as for descent.
angle of climb [ ° ]
rate of climb [fpm]
FL

distance
FL

 GF 100
distance
≈ climb gradient [%] x GS
climb gradient [%]
AIRLINE TRAINING CENTER, INC.
 AoC 2  1
Rate of climb, angle of climb,
climb gradient
• Exercises
Q. What RoC do we need to climb on a SID with a standard
gradient? Climb speed 105 kts.
350 fpm
AIRLINE TRAINING CENTER, INC.
Rate of climb, angle of climb,
climb gradient
• Exercises
Q. Due to obstacles in the departure area, a SID requires 7% up
to 3000ft. At 105 kts climb speed, what RoC do we need?
750 fpm
AIRLINE TRAINING CENTER, INC.
Rate of climb, angle of climb,
climb gradient
• Exercises
Q. At 3 NM from the departure end of the runway is a church
located on a small hill. The top of the church is at 700ft above
airport elevation. What is the AoC, climb gradient en RoC
required to cross the top with a 500ft clearance? During takeoff
you cross the end of the runway at 150ft at 90 kts.
AoC: 3,5°
Climb gradient: 6%
RoC: 525 fpm
700ft
150ft
AIRLINE TRAINING CENTER, INC.
Content – G2
 1 in 60 rule
 Speed factor, ground factor, air factor
 Rate of descent, angle of descent,
descent gradient
 Rate of climb, angle of climb, climb
gradient
 Descent planning
 Wind and time corrections
AIRLINE TRAINING CENTER, INC.
Descent planning
• non-pressurized aircraft
 500 feet/min rate of descent is the standard, unless there is a
good reason to descend at a higher rate.


altitude to loose
2
Minutes to descend =
1000
altitude to loose
Distance to descend =
 2  GF
1000
 Remember not to calculate your descent until ground but til
your pattern altitude!
AIRLINE TRAINING CENTER, INC.
Descent planning
• Exercises
Q. How many miles to loose 3000ft at 120 kts GS?
AIRLINE TRAINING CENTER, INC.
12 NM
5000ft
100 kts
17 NM
4000ft
150 kts
20 NM
Descent planning
• Exercises
Q. Calculate TOD in nautical miles and minutes?
present alt.
airport elev.
airspeed
wind
8500ft
KSDL - 1500ft
110 kts
10 TW
5500ft
KRYN - 2500ft
100 kts
15 HW
11500ft
KFLG - 7000ft
145 kts
20 HW
! Reach the airport at TPA (normally 1000ft AGL).
• 12 min – 24 NM before KSDL
• 4 min – 6 NM before KRYN
• 7 min – 14 min before KFLG
AIRLINE TRAINING CENTER, INC.
Descent planning
• Exercises
Q. At which distance from KFFZ will you start the descent?
Descent speed 90 kts (no wind).
A/FD KFFZ
pattern alt. 800ft
TOD = 20 NM before KFFZ
AIRLINE TRAINING CENTER, INC.
Content – G2
 1 in 60 rule
 Speed factor, ground factor, air factor
 Rate of descent, angle of descent,
descent gradient
 Rate of climb, angle of climb, climb
gradient
 Descent planning
 Wind and time corrections
AIRLINE TRAINING CENTER, INC.
• wind component
headwind
Wind and time corrections
crosswind
tailwind
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• crosswind component
1
3
AIRLINE TRAINING CENTER, INC.
2
3
3
3
Wind and time corrections
• crosswind component
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• tail-/headwind component
2
3
3
3
TAIL
AIRLINE TRAINING CENTER, INC.
1
3
2
3
HEAD
3
3
Wind and time corrections
13kts
• tail-/headwind component
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• wind component
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• Exercises
Q. Calculate crosswind and head/tailwind component?
wind: 340/15
300/10
015/20
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• Exercises
Q. Calculate crosswind and head/tailwind component?
wind: 080/20
230/30
360/15
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• time correction
 HW / TW component divided by AF = time correction [sec] per
minute flight time
 time correction per minute x leg time = time correction for the
leg
B
Q: new flight time with
20kts headwind?
A
11min 40 sec
AIRLINE TRAINING CENTER, INC.
example
This is an approximation (thumb rule), if you calculate it
exactly, you will found 12 min. as new flight time
Wind and time corrections
• drift/wind correction angle
crosswindcomponent
AF
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. Calculate crosswind and head/tailwind component?
Crosswind comp. = 8 kts (2/3)
Headwind comp. = 8 kts (2/3)
Wind, 300°/13kts
AIRLINE TRAINING CENTER, INC.
Speed factor, ground factor, air factor
• Exercises
Q. How many ground miles will you fly in a minute?
16kts
Reported wind:
090°/22kts
2 NM/min
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• Exercises
Q. Calculate the heading correction, 90 KTAS?
wind: 340/15
300/10
150/20
AIRLINE TRAINING CENTER, INC.
3° L
5° L
7° R
Wind and time corrections
• Exercises
Q. Calculate the heading correction, 120 KTAS?
wind: 080/20
230/30
360/15
AIRLINE TRAINING CENTER, INC.
4° L
15° R
8° L
Wind and time corrections
• Exercises
VFR navigation
• PA 28 – 110 KTAS
• wind 120/15
• diversion to alternate airport: course 060°, distance 36 NM
Q. What will be your ETE and heading to your alternate airport?
Heading: 067°
ETE: 21 min
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• Exercises
VFR navigation
• DA 42 – 145 KTAS
• wind 060/25
• diversion to alternate airport: course 210°, distance 45 NM
Q. What will be your ETE and heading to your alternate airport?
Heading: 205°
ETE: 16 min
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• Exercises
Q. Which heading to fly and what will be your estimated leg
time?
Track: 160°
Distance: 11 NM
Wind: 030/18
HDG: 154°
Leg time: 5,5 min
AIRLINE TRAINING CENTER, INC.
Wind and time corrections
• Exercises
Q. Calculate the time correction? 100KTAS, leg time 3 min.
wind: 340/15
300/10
150/20
AIRLINE TRAINING CENTER, INC.
+ 30 sec.
+ 9 sec.
- 30 sec.
Wind and time corrections
• Exercises
Q. Calculate the flight time outbound SNOWL and the heading
and time correction outbound in the procedure turn (course
167°). 100 KTAS.
Extra info: Outbound timing SNOWL  1 to 3
minutes (ICAO), we take 3 minutes (no wind)
with a speed of 100 KTAS and we stay within
10NM from SNOWL
2,5 min.
+ 0 sec / 11° R
Stay within
10 NM from
SNOWL
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