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Refer to figure or Flight Planning Manual MRJT 1 Figure 4.5.2 and 4.5.3.4. 
Given:

Distance C to D: 540 NM 
Cruise 300 KIAS at FL 210 
Temperature Deviation from ISA: +20°C 
Headwind component: 50 kt 
Gross mass at C: 60000 kg

The fuel required from C to D is:

  • A
    3680 kg
  • B
    4620 kg
  • C
    4228 kg
  • D
    3350 kg

Refer to figure.

First Step: Find out TAS - top right corner of chart and apply ISA Dev based on "Note".
TAS = 406 kt
Note: "INCREASE TAS BY 1 KNOT PER DEGREE ABOVE ISA"

  • ISA Deviation = +20ºC
TAS = 406 + 20 = 426 kts
Second Step: Calculate Groundspeed from TAS and Headwind component.
  • GS = 426 kt - 50 kt = 376 kts
Third Step: Using the formula: NAM = NGM x TAS/GS; Convert NGM into NAM to enter the table.
  • NAM = 540 x 426/376 = 612 NAM
Fourth Step: Enter the table with a mass of 60 000 kg by finding the value corresponding to the intersection of "60 000" taken from the first column and "0" from the first row.
  • Read the corresponding value of 3898 NAM.
Fifth Step: From 3898 NAM subtract 612 NAM = 3286 NAM and find the mass corresponding to this value on the table.
There is no distance of 3286 NAM on the table - Interpolation is needed between 3284 NAM and 3299 NAM.
- 3284 NAM corresponds to a mass of: 55 800 kg
- 3299 NAM corresponds to a mass of: 55 900 kg
By interpolation, we get to an approximate value of 55 813 kg for 3286 NAM.
Sixth Step: Find fuel required by deducting 55 813 kg from the inital mass of 60 000 kg = 4187 kg.
Don't forget to correct this value for ISA dev based on the "Note: Increase fuel reuired by 0.5 percent per 10 degrees C above ISA"
ISA +20ºC => add 1%
4187 kg x 1% = approx. 42 kg
4187 kg + 42 kg = 4229 kg.

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