How to - Fuel Planning

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An abbreviated method is provided to calculate the fuel required for your flight. Note that the values mentioned below are for total fuel required for both engines assuming Maximum Take Off Weight.

An example calculation is provided for reference.

Taxi Fuel
30 lbs / minute.

Take Off Fuel
200 lbs required until reaching 1,000 ft.

Climb Fuel
2,800 lbs per hour at a climb speed of 150 KIAS, approximately 1,000 FPM.
Equivalent True Airspeed for 150 kt Indicated Airspeed:

Altitude (ft)	IAS (kt)	TAS (kt)
20,000	150	210
15,000	150	195
10,000	150	180
5,000	150	165

Cruise Fuel 
Cruise power setting 14,200 RPM. The fuel flow remains approximately stable at 2,600 lbs/hr. 

Altitude (ft)	IAS (kt)	TAS (kt)	Fuel Flow (lbs/hr)
20,000	190	265	2,600
15,000	190	250	2,600
10,000	190	230	2,700
5,000	190	210	2,700

Descent Fuel
1,800 lbs per hour. Speed of 200 KIAS, approximately 1,000 FPM at 12,500 RPM.
Equivalent True Airspeed for 200 kt Indicated Airspeed:

Altitude (ft)	IAS (kt)	TAS (kt)
20,000	200	280
15,000	200	260
10,000	200	240
5,000	200	220

Approach Fuel
200 lbs fuel required from 2,000 ft AGL at 200 KIAS, execute the approach and a Go Around until reaching 1,000 ft AGL in clean configuration.
Holding/Reserve Fuel
2,800 lbs per hour, holding at 1,000 ft AGL at 200 KIAS.

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Example Calculation
For this example, we will consider a 200 NM flight
•    Departure airport elevation: Sea Level
•    Departure airport taxi time: 10 minutes
•    Arrival airport elevation: 2,000 ft
•    Cruise level: FL150
•    Average climb wind: 20 kt headwind
•    Average cruise wind: 30 kt headwind
•    Average descend wind: 10 kt headwind

 

Total Fuel Required

Taxi: 300 lbs
Take Off: 200 lbs
Climb: 654 lbs
Cruise: 997 lbs
Descent: 420 lbs
Approach fuel: 200 lbs
Reserve Fuel: 1,400 lbs
Contingency Fuel (5% of Take Off + Climb + Cruise + Descent + Approach): 124 lbs
Total: 4,295 lbs

 

Calculation Breakdown

Taxi Fuel
10 minutes taxi at 30 lbs per minute: 300 lbs.

Take Off Fuel
Fuel required to reach 1,000 ft AGL: 200 lbs.

Climb Fuel
150 KIAS will be maintained throughout the climb, leading to an increasing TAS as the altitude increases. For climbing it is common practice to consider the TAS at a point two thirds of the desired cruise altitude. 

In our case climbing from sea level to 15,000 ft, 2/3 would equal 10,000 ft. 
Extracting the TAS from the Climb table at 10,000 ft gives 240 KTAS.

An average climb rate of 1,000 FPM will be assumed for calculation purposes. 
Take Off fuel accounts for fuel up to 1,000 ft AGL, therefore we will take 14 minutes to climb the remaining 14,000 ft to reach our cruise level of 15,000 ft.

In this example we are assuming a climb headwind component of 20 kt, obtaining a resulting Ground Speed of 220 kt (240 KIAS – 20 kt).
We will now compute the distance taken on the climb: 14 minutes at 220 kt = 51 NM.

During the climb the average fuel flow is 2,800 lbs per hour. The climb will take 14 minutes, therefore requiring 654 lbs.

Cruise Fuel
Using the table provided we extract at 15,000 ft a cruise TAS of 250 kt and a fuel flow of 2,600 lbs per hour.
Before we can compute our cruise fuel, we need to know the length of our cruise segment. The distance required to climb was calculated previously (51 NM), we now need to calculate the descent distance in order to compute the remaining cruise distance.

Our arrival airport is at an elevation of 1,000 ft. From 15,000 ft we will need to descend 14,000 ft.
Assuming a rate of descent of 1,000 FPM this equates to 14 minutes. Our TAS is required and this can be extracted from the table located in the Descent Fuel section. 

When descending we will consider the TAS at the halfway point throughout the descent. We will be descending 14,000 ft, half equates to 7,000 ft and we add the arrival elevation to this figure giving an altitude of 8,000 ft for our TAS. At a descent speed of 200 KIAS this corresponds to approximately 230 KTAS. 
The average descend wind is 10 kt headwind, giving a resulting Ground Speed of 220 kt.
14 minutes descending at 220 kt Ground Speed will cover 51 NM.

Total flight distance of 200 NM, minus climb distance (51 NM), minus descent distance (51 NM) = 98 NM cruise distance.

At our cruise level the expected headwind component is 30 kt. TAS 250 kt – 30 kt = 220 kt Ground Speed.
98 NM at a Ground Speed of 220 kt takes 27 minutes.
23 minutes at a fuel flow of 2,600 lbs per hour requires 997 lbs.

 

Descent Fuel

The descent distance and time was computed in the Cruise Fuel section: 14 minutes and 51 NM covered.

Average descent fuel flow is 1,800 lbs per hour. On a 14 minute descent the fuel required is 420 lbs.

Approach Fuel

Standard Approach fuel required is 200 lbs.

Reserve Fuel

30 minutes reserve fuel: 1,400 lbs.