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Thread: Q5290

  1. #1
    Junior Member
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    Jan 2013
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    Q5290

    hi, i don't get that step
    From the table,150 000 kg read 2464 NAM 2464 - 2000 = 464 NAM
    From the table, 464 NAM read 133 250 kg <== Where does this come from?

    Neither this next
    FUEL = 150 000 - 130 325 = 19 675 kg <== Where does 130325 come from?

    Thanks in advance

  2. #2
    Senior Member
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    Good morning,

    If you could post the entire question and any images that come with the question I would be glad to help you out.

    Sincerely,
    Patrick van Harten
    ATPL(A) Student

  3. #3
    Junior Member
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    Mar 2013
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    27
    Good evening!

    The explanation for the question is a bit sketchy and not entirely correct so I'll try to be a bit more thorough...

    150 000 kg -> 2464 NAM
    2464 NAM - 2000 NAM = 464 NAM

    464 NAM is between two weights (130 200 kg -> 451 NAM and 130 400 kg -> 472 NAM) but not in the middle, which would be 461.5 NAM, i.e. we need to find the weight increments per change in NAM:
    (130 400 kg - 130 200 kg) (472 NAM - 451 NAM) = 200 kg 21 NAM = 9.52 kg/NAM

    Difference from 130 200 kg -> 451 NAM to the weight corresponding to 464 NAM is:
    (464 NAM - 451 NAM) x 9.52 kg/NAM = 123.76 kg

    Since 464 NAM is higher than 130 200 kg -> 451 NAM, the weight difference above must be added to the 130 200 kg:
    130 200 kg + 124 kg = 130 324 kg

    Total uncorrected fuel consumption: 150 000 kg - 130 324 kg = 19 676 kg.

    Corrections then has to be made from the climb and descent correction tables on the side.

    For climb, the correction given in the climb correction table is in 1000 kg and reading from FL350 -> 150 000 kg gives 2.1 or 2100 kg.
    For descent, the correction given in the descent correction table is in 100 kg and reading from FL290 and above -> 130 324 gives near enough 0.6 or 60 kg.

    Total correction to be made is: 2100 kg + 60 kg = 2160 kg.

    Total fuel consumption is: 19 676 kg + 2160 kg = 21 836 kg.

    So, we've ended up at a random number where 21 760 kg is the closest alternative. The discrepancy according to the explanation given to the question is in the descent correction. I'm using the appendix in the question database where the table clearly states "CORRECTION ON FUEL CONSUMPTION (100 KG)" and not 1000 kg as has been used in the explanation. I haven't got the relevant CAP handy, so if anyone could check whether that differ from the table in question it will sort where the error is.

    If the CAP reads as the image, 21 760 kg is the correct alternative, and if the CAP reads different to the image, 22 360 kg is the correct alternative as my answer will be 540 kg, i.e. the difference between 60 kg and 600 kg, too low (21 836 kg + 540 kg = 22 376 kg).

    Hope this helps regarding solving the question and applying appropriate corrections...
    Last edited by TJ-ProPilot; 08-21-2013 at 09:29 PM.

  4. #4
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    Jan 2013
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    thanks a lot

  5. #5
    Junior Member
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    Mar 2015
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    ...and it still hasn't been corrected!!!!

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