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Alternate Fuel in Safe Endurance Calculation
RMaya83
Topic Author
RMaya83 created the topic: Alternate Fuel in Safe Endurance Calculation
Hi Everyone,
Just wanted to ask if anyone can help me understand how alternate fuel would factor into Safe Endurance for the PNR calculation?
For air transport when calculating trip fuel for the PNR calculation I would do the following:
(Fuel on Board Start - Taxi - Final Reserve - Holding at departure aerodrome - Alternate) / 1.1 = Trip Fuel
I would then convert Trip Fuel to Safe Endurance.
However I saw in another post that alternate fuel should be added back to trip fuel to get Safe Endurance for PNR?
(Fuel on Board Start - Taxi - Final Reserve - Holding at departure aerodrome - Alternate) / 1.1 = Trip Fuel + Alternate Fuel
Is the second formula appropriate to get the safe endurance where alternate fuel is concerned?
bobtait replied the topic: Alternate Fuel in Safe Endurance Calculation
This seems to be a common point of confusion. If you are calculating a PNR, the ONLY thing that concerns you is the total fuel on board when you dip the tanks before start-up. Forget all about the planned trip (destination holding and destination alternates have nothing to do with it). The departure aerodome IS your destination as far as a PNR is concerned.
If the DEPARTURE AERODROME has an OPR for holding or provision of an alternate, then that fuel must be taken out along with the usual reserves when you are calculating the safe endurance.
When it comes to your FLIGHT PLAN, then you must consider the trip fuel required to the destination along with the normal final reserve and contingency fuel and any destination holding and alternate requirements. However, that's a completely separate calculation and has nothing to do with the PNR.
RMaya83 replied the topic: Alternate Fuel in Safe Endurance Calculation
That makes sense Bob thanks. I finally managed to pass my Performance Exam with a good score after failing the first time. For the second time sitting the exam the PNR questions did not include any alternate requirements. Nonetheless thanks for clarifying this question as it's good to know how alternate fuel is factored into Safe Endurance for PNR calculations.
