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Refer to figure or CAP 758 figure 3.14.
Given the following information, determine the fuel required to cover a ground distance of 99 NM:

Pressure altitude: 7 500 ft
OAT: ISA
Mass: 7 500 kg
TAS: 145 kt
Wind: 315°(M)/20 kt
Track: 135°M
  • A
    241 kg
  • B
    253 kg
  • C
    24.8 kg
  • D
    248 kg

Refer to figure.
Firstly, calculate the Fuel flow at 7 500 ft for Mass 7 500 kg:

  1. Enter the graph from pressure altitude 7 500 ft.
  2. Move horizontally to the right until crossing the mass 7 500 kg curve (7.5 solid line).
  3. Continue vertically down and read Fuel Flow: 413 kg/hr

Secondly, calculate the flight time to cover 99 NM:

  1. The angle difference between wind direction and track is: 315° - 135° = 180°, which means that the helicopter experiences a tailwind of 20 kt.
  2. So, its Groundspeed is: TAS + 20 kt = 165 kt.
  3. Thus, the flight time is: Distance / GS = 99 NM / 165 kt = 0.6 hr.
Therefore, the fuel required in kg to cover the distance of 99 NM is: Flight time x Fuel Flow = 0.6 hr x 413 kg/hr = 248 kg.

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