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Rhazeltine created the topic: PNR calculation
On page 4.49 of the cpl performance book there is an example of a PNR calculation. The example calculates the safe endurance but includes the 120 liters holding fuel as flight fuel. Ie it then divides by the 1.15. If holding fuel is not flight fuel, surely the 120 l should be subtracted after the division. Please help as I sit my exam very soon and this is doing my head in.
No, the 120 litres of holding fuel is not flight fuel, that is why you take it out beore you divide by 1.15. If you start with the total fuel on board [680 litres in this case], and put aside the taxi fuel, the fixed reserve and the holding fuel, you are left with 455 litres. That now represents 115% of the flight fuel.
So the flight fuel will be 455 diveded by 1.15 which is 396 litres.