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Refer to figure or Flight Planning Manual MRJT 1 Figure 4.5.3.1. 
Given:

Flight leg: Top of Climb TOC to enroute point B 
Flight time from TOC to B: 48 minutes 
Flight regime: Long Range Cruise, FL280 
Temperature: ISA -5°C 
Take off Mass: 65 000 kg 
Climb Fuel: 1100 kg

Calculate: Fuel consumption from take-off to enroute point B.

  • A
    2000 kg
  • B
    3370 kg
  • C
    3870 kg
  • D
    2270 kg

Refer to figure.
Airplane mass at TOC = 65 000 - 1100 = 63 900 kg
Range of the airplane = 5184 NM

Get the TAS = 443 kts
Apply ISA deviation correction:

  • Note: Decrease TAS by 1 knot per degree C below ISA

TAS = 443 - 5 = 438 kts

Distance in 48 minutes with TAS (438 kts) = 438 x (48 / 60) = 350 NM

Deduct 350 NM from the range (5184 NM) to get the range after the flight (4834 NM)
Find the mass of the airplane corresponding to the range (4834 NM) => interpolate between 61 600 kg and 61 700 kg = 61 650 kg

Airplane mass after the flight = 61 650 kg
Cruise Fuel consumption = airplane mass at takeoff — climb fuel — airplane mass after the flight
Cruise Fuel consumption = 65 000 kg - 1100 kg - 61 650 kg = 2250 kg

Apply ISA deviation correction:

  • Note: Decrease fuel required by 0.6 percent per 10 degrees C below ISA.
  • Therefore, we must apply a correction of 0.3% => 2250 x 0.3% = 6.75 kg

2250 kg – 6.75 kg = 2243 kg
Fuel consumption = 2243 kg + 1100 kg = 3343 kg

Closest Answer = 3370 kg

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