Question Bank Flight Planning Q5274

[JDTC]

Hi, wondered if anyone knew how on earth the answer 51,860Kg was derived here? There doesn't seem to be enough information in the question to determine if the landing weight correction needs to be applied...? Any help would be greatly appreciated - ta.:ugh:

[cefey]

What QB are you using? Just write the whole question and Im sure someone will help you;)

[JDTC]

This is ATPL Online - in order to see the question properly you need to see the tables on the 'additional information' section. Question: The flight crew of a turbojet aeroplane prepares a flight using the following data: Flight leg ground distance: 4 000 NM, Flight level FL 370; "Long range" flight regime, Effective wind at this level: head wind of 50 kt. Temperature: ISA, Centre of gravity (CG): 37 %, Pack flow : LOW (LO), Anti ice: OFF, Reference landing mass: 140 000 kg, Taxi fuel: 500 kg, Final reserve fuel: 2 400 kg. The fuel quantity which must be loaded on board the aircraft is:? :hmm:

[cefey]

Question: The flight crew of a turbojet aeroplane prepares a flight using the following data:
Flight leg ground distance: 4 000 NM,
Flight level FL 370;
"Long range" flight regime,
Effective wind at this level: head wind of 50 kt.
Temperature: ISA,
Centre of gravity (CG): 37 %,
Pack flow : LOW (LO),
Anti ice: OFF,
Reference landing mass: 140 000 kg,
Taxi fuel: 500 kg,
Final reserve fuel: 2 400 kg.
The fuel quantity which must be loaded on board the aircraft is:?



I like to break questions down to "1 info per line", which saves you a lot of time later on, when you start solving them. But you dont have to write down things like "cg 37%" or "landing mass", that will be "standard" for the tables.

You have to use 2 different tables here.
1. First of all, you need to convert ground-distance into air-distance, using table (Long Range Cruise Above FL250).
Air distance is 4479NM.

2. Now, you go to the other table, (Flight Planing From Break Release To Landing).
Make sure that you are using right table (RLM 140.000kg, ISA, CG37%)!
You have to interpolate between 4400NM and 4500NM:
((49401-48233)/2) + 48233)=49156kg.
Dont forget to correct it for LOW PACK FLOW (see correction on the bottom of the table), by -0.4%. Which will give us total fuel consumption of 48960kg.

The total fuel load therefore is: Trip fuel 48960kg + Final Reserve Fuel 2400kg + Taxi Fuel 500kg = 51860kg

Be aware of tricky things such as "fuel required from break release until landing", then you have not account for taxi fuel. And of course, you right flight level, dont forget anti ice and pack flow correction!

[JDTC]

Thank you so much for the above. We must be looking at different tables though as I get NAM = 4473 opposed to 4479 and the integrated values I get for 4400 and 4500 are 49,555 and 50,739 respectively opposed to 49,401 and 48,233 respectively. It's very strange as I follow your explanation but the data in the question bank seems to be different.