g2 - rules of thumb

7/31/2019 G2 - Rules of Thumb

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AIRLINE TRAINING CENTER, INC.

Rules of thumb

General Briefing G2

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




Content – G2

1 in 60 rule








1 in 60 rule

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.

• Mathematics




1 in 60 rule

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°

• Mathematics

≈ 60°

r




1 in 60 rule

1 rad ≈ 60 ° with arc length = radius

For an angle of 1°, arc length ≈ radius / 60

• Mathematics

1°

not to scale

r

r / 60


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1 in 60 rule

• The 1 in 60 rule

1°

60 NM

1 NM

1°

1 NM

≈ 100ft

≈ 6000ft

3°

1 NM

≈ 300ft Standard ILS

not to scale



1 in 60 rule

• Exercises

A

B

α

• at 60 NM, 3° B ≈ … NM ?

• at 15 NM, 5° B ≈ … NM ?

• at 25 NM, 2° B ≈ … NM ?

• at 1 NM, 3° B ≈ … ft ?

• at 10 NM, 3° B ≈ … ft ?

• at 5 NM, 4° B ≈ … ft ?

• at 60 NM, 2 NM off α ≈ ?

• at 12 NM, 4 NM off α ≈ ?

• at 20 NM, 6 NM off α ≈ ?

• at 1 NM, 200ft off α ≈ ?

• at 5 NM, 2000ft off α ≈ ?

• at 6 NM, 1800ft off α ≈ ?



1 in 60 rule

• Exercises

A

B

α

• at 60 NM, 3° B ≈ 3 NM

• at 15 NM, 5° B ≈ 1,25 NM

• at 25 NM, 2° B ≈ 0,8 NM

• at 1 NM, 3° B ≈ 300 ft

• at 10 NM, 3° B ≈ 3000 ft

• at 5 NM, 4° B ≈ 2000 ft

• at 60 NM, 2 NM off α ≈ 2°

• at 12 NM, 4 NM off α ≈ 20°

• at 20 NM, 6 NM off α ≈ 18°

• at 1 NM, 200ft off α ≈ 2°

• at 5 NM, 2000ft off α ≈ 4°

• at 6 NM, 1800ft off α ≈ 3°




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 °




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?

1500ft

5500ft

20NM

minimum angle ≈ 2 °




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°




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




1 in 60 rule

• Exercises

Q. How many nautical miles is the green segment of this DME arc? Procedure is flown at 120 KTAS.

R090

12DME arc

turn radius = TAS/200

7,4 NM

Arc distance between R050 and R090 = 8.0NM Turn radius = 0.6NM

Green segment = 8.0 – 0.6 = 7.4 NM




1 in 60 rule

Q. At which altitude approximately should you start the descent at the FAF arriving via FLORA?

• Exercises

≈ 2920 ft

Distance threshold to FAF = 8.8NM ≈ 9NM 1 in 60 rule: 9NM with a 3°≈ 2700ft 2700ft + TCH (≈60ft) + apt. elev. (≈160ft)




1 in 60 rule

Q. At which altitude should you cross 2.5DME ILST?

≈ 1425 ft

• Exercises





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 ≈ ?

• Air factor

6 NM/min

example




Q. Calculate the air factor for the given TAS / Mach number?


• Exercises

• 90 KTAS AF = ?

• 120 KTAS AF = ?

• 150 KTAS AF = ?

• 180 KTAS AF = ?

• 100 KTAS AF = ?

• M .78 AF ≈ ? (A320)

• M .84 AF ≈ ? (B747)

• M .72 AF ≈ ? (AVRO RJ)




Q. Calculate the air factor for the given TAS / Mach number?


• Exercises

• 90 KTAS AF = 1,5 NM/min

• 120 KTAS AF = 2 NM/min

• 150 KTAS AF = 2,5 NM/min

• 180 KTAS AF = 3 NM/min

• 100 KTAS AF ≈ 1,7 NM/min

• M .78 AF ≈ 8 NM/min

• M .84 AF ≈ 8,5 NM/min

• M .72 AF ≈ 7 NM/min




Q. Calculate the ground factor for the given TAS and wind?


• Exercises

• 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




Navigation exercises:


• Exercises

• 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




Navigation exercises:


• Exercises

• 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




IFR navigation exercises:


• 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




IFR navigation exercises:


• Exercises

• Under radar vectors to final on base leg. Speed 100 KTAS,TW 10 kts. How much time left before intercepting final?

2 min




Q. ATC request ETA overhead point EXIBA, distance to EXIBA is 80 NM. Speed 145 KTAS, HW 20 kts.


• Exercises

13:4514:25




Q. ATC request ETA overhead point DOBAL, distance to DOBAL is 30 NM. Speed 110 KTAS, HW 20 kts.


• Exercises

16:3216:52




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

• Exercises




Content – G2

1 in 60 rule









[ft]distance

[ft]altitude][][tan

rad rad

NMdistance

ftaltitude

• Mathematics - AoD

6000[NM]distance

[ft]altitude][

rad





6000M]distance[N

[ft]altitude][

rad


100M]distance[N

100[FL]altitude][

6000M]distance[N

[ft]altitude

60

][

100M]distance[N

[ft]altitude

][





M]distance[N

FL][

≈ angle of descent [ ° ]


ftaltitude

NMdistance

100M]distance[N

100[FL]altitude][





• Mathematics - RoD

]AoD[

hr / NMGS

RoD [ft/min]

M]distance[N

FL][AoD

GS[NM/hr]

RoD[FL/hr]][AoD





• Mathematics - RoD

GS[NM/hr]

RoD[FL/hr]][AoD

GS[NM/hr]

100

60]RoD[ft/min

][AoD

60100GS[kts]][AoD]RoD[ft/min

100GF[NM/min]][AoD]RoD[ft/min Rate of descent [ ft/min]





• Descent gradient

descent gradient [%] 12AoD

3°≈ ?

4°≈ ? 7 %

5 %

example

Rate of descent [fpm] ≈ descent gradient [%] x GS




Q. Calculate angle of descent, descent gradient and rate of descent?


•Exercises

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 ? ? ?




Q. Calculate angle of descent, descent gradient and rate of descent?


•Exercises

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




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?


•Exercises

RoD ≈ 1300 fpm




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.


•Exercises

6200ft

7.0 15.012.0

5000ft

4000ft

Final RoD ≈ 450 + 100fpm

AoD ≈ 4°

RoD ≈ 600 fpm

1900ft

AoD ≈ 2 °

RoD ≈ 300 fpm




Q. What is the AoD and RoD required to reach the stepdown fixes at the minimum altitudes? GS is 75 kts.


•Exercises

KCHD, VOR Rwy 4R

4°500 fpm

3°375 fpm




Q. What is the final RoD required to the MDA? GS is 75 kts.


•Exercises

KSDL, VOR A

450 + 200 fpm




Q. What RoD is required to stay on the glide of a standard ILS approach, at 90 – 100 – 120 – 150 kts GS?


•Exercises




Q. What is the angle of descent and rate of descent required to follow the published final approach?

AoD ≈ 4°RoD ≈ 800 fpm


•Exercises




Q. What is the descent gradient and required rate of descent of this non-precision approach?

Descent grad. ≈ 6% RoD ≈ 540 fpm


•Exercises




Content – G2

1 in 60 rule




Descent planning

Wind and time corrections




Rate of climb, angle of climb,climb gradient

• thumbrules

climb gradient [%] 12AoC

≈ climb gradient [%] x GS

Same as for descent.

distance

FL

angle of climb [ ° ]

100GFdistance

FL

rate of climb [fpm]




Q. What RoC do we need to climb on a SID with a standard gradient? Climb speed 105 kts.

350 fpm


• Exercises



i i




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.


• Exercises

150ft

700ft

AoC: 3,5°Climb gradient: 6%

RoC: 525 fpm




Content – G2

1 in 60 rule




Descent planning





Descent planning

500 feet/min rate of descent is the standard, unless there is a good reason to descend at a higher rate.

Minutes to descend =

Distance to descend =

Remember not to calculate your descent until ground but til your pattern altitude!

• non-pressurized aircraft

21000

loosetoaltitude

GF2

1000

loosetoaltitude




Q. How many miles to loose 3000ft at 120 kts GS?

5000ft 100 kts

4000ft 150 kts

Descent planning

12 NM

•Exercises

17 NM

20 NM




Q. Calculate TOD in nautical miles and minutes?

Descent planning

•Exercises

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




Q. At which distance from KFFZ will you start the descent? Descent speed 90 kts (no wind).

Descent planning

A/FD KFFZ pattern alt. 800ft

TOD = 20 NM before KFFZ

•Exercises




Content – G2

1 in 60 rule




Descent planning






• wind component

crosswind

h e a d w i n d

t ai l wi n d





3

1

3

2

• crosswind component

3

3





• crosswind component





3

2

3

3

• tail-/headwind component

3

3

3

2

HEADTAIL

3

1





1 3 k t s

• tail-/headwind component





• wind component





•Exercises

Q. Calculate crosswind and head/tailwind component?

wind: 340/15

300/10 015/20





•Exercises


wind: 080/20

230/30 360/15





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

• time correction

example

A

B

Q: new flight time with 20kts headwind?

11min 40 sec

This is an approximation (thumb rule), if you calculate it

exactly, you will found 12 min. as new flight time





• drift/wind correction angle

AF

componentcrosswind






Wind, 300°/13kts

Crosswind comp. = 8 kts (2/3)

Headwind comp. = 8 kts (2/3)

•

Exercises




Q. How many ground miles will you fly in a minute?


Reported wind: 090°/22kts

2 NM/min

1 6 k t s

•

Exercises





•

Exercises

Q. Calculate the heading correction, 90 KTAS?

wind: 340/15

300/10 150/20

3° L

5° L7° R





•

Exercises

wind: 080/20

230/30 360/15

Q. Calculate the heading correction, 120 KTAS?

4° L

15° R 8° L





•

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





•

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




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

•

Exercises






•

Exercises

Q. Calculate the time correction? 100KTAS, leg time 3 min.

wind: 340/15

300/10 150/20

+ 30 sec.

+ 9 sec.- 30 sec.





•

Exercises

Q. Calculate the flight time outbound SNOWL and the heading and time correction outbound in the procedure turn (course 167°). 100 KTAS.

2,5 min.+ 0 sec / 11° R

Stay within

10 NM from

SNOWL

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

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g2 - rules of thumb

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