Hello Fellas,
I am trying attempt Exercise 5.6, No2 in the performance book and I am a bit confused with the Gross weight used to get the TAS from table 4.4 of the supplement. In the answer the value of TAS has been extracted by interpolating the values in ISA +20 between 15000 and 20000. However, in the question the Take off weight limit used is 2870 so, should the TAS values been interpolated between the 2950kg and 2500kg?
Hi Nixor,
The difference between the TAS at 2950kg and 2500kg at FL 150 and FL200, 65%MCP varies from 3 to 4 knots. So the TAS at 2870kg is going to be within 1 knot of that at 2950kg. By using the TAS for 2950kg you are assured of having sufficient fuel for the flight.
Interpolating for 2870kg is probably outside the design of the question.
Cheers W
