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Performance - ID 320138

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  • Performance - ID 320138

    Can someone help me with this question(3201338), even though the question is asking for the distance on dry runway but the calculated answer is taking wet runway factor into account.
    I have a exam next week, and need some help with this question.
    I understand there is a bit slippage with some of the questions, so this could be a case of a wrong answer on the question bank ? For a turboprop powered aeroplane, a 2200 m long runway at the destination aerodrome is expected to be "wet". The "dry runway" landing distance, should not exceed:


  • #2
    The given answer is correct!
    The oddity is with the wording of question, "the dry runway" bit! Very confusing!
    I'll try and explain how I think the examiner has arrived at this terminology.
    Ops states that a turboprop must plan to land and stop within 70% of the LDA on a dry runway (or a factor of 1.43) the remaining 30% is the safety factor required under the regulations.
    If the runway is wet (or expected to be wet) an additional 15% (or a factor of 1.15) safety factor is required. This equates to planning to land and stop within 61% of the LDA and the remaining 39% accounts for the wet condition and regulation.
    It's this 61% that the examiner considers to be the "dry runway" element of the calculation!
    So using the factors we get.... The total factor for the 'wet runway' = 1.43 x 1.15 = 1.64.
    2200m / 1.64 = 1341m
    So we can say that the dry runway element of the 2200m LDA is 1341m and the remaining 859m accounts for the wet factor and the regulation factor.
    Please remember we don't write the questions. This particular one is pretty old and may well have been rewritten in a more sensible presentation.


    • #3
      That makes more sense Colin, many thanks for the explanation.
      I will stick with this explanation and appeal anything that isn't clear enough.



      • #4
        Hi Navi, I too struggled with this question! Hoping your exams went well... I'm doing PERFORMANCE next week, if there is anything you can remember - or can help with any of the recent questions I've posted then please feel free to let me know. Thank you, Ali.