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A crew plan for a full flap landing (30°) but, due to distraction, fail to extend flaps from the approach to the landing setting until a few seconds before touchdown. Which of the following statements is correct assuming the correct glidepath was flown to touchdown?

  • A

    The aircraft is likely to float and touch down further along the runway.

  • B

    There is no problem if the aircraft attitude is not changed.

  • C

    There is less risk of a hard landing.

  • D

    A go-around is unnecessary.

Refer to figures.
Note: There are quite a few factors which affect an aircraft's landing performance and handling. The question and available options do not take into account these different factors. That is to say that the examiner has been very closed minded in writing this question, using a "tunnel vision" approach.

The current correct option is simply the only answer that makes any sense. It is the "most correct" out of a bad bunch, and in itself is arguable, but depending on the circumstances we have not been told, may be true, whereas the other answers are not true in any circumstance.

For a given runway length and airplane weight, selecting a greater flap setting will increase the wing’s effective camber and the lift coefficient, which reduces the stalling speed.
  • As a consequence, the take-off speeds are reduced (the same lift will be created at smaller air speed due to greater lift coefficient). This will reduce the take-off run.
  • Flap extension during landings provides several advantages by:
  • producing greater lift and permitting lower landing speed;
  • producing greater drag, permitting a steep descent angle without airspeed increase, therefore Reducing the length of the landing roll.

Therefore, the answer here is that using less flaps than expected will cause significantly less drag than expected, so the aircraft may float for a while longer, and therefore have a longer landing roll (that is assuming that the pilot rotates enough during the flare, which has not been specified in the question).

As mentioned above, none of the other answers could be correct:

  • There will be a large difference to the handling characteristics, even if the attitude remains the same.
  • There is arguably a higher risk of a hard landing due to the lower "cushioning" effect of the lower flap setting. This one takes longer to explain but most pilots know it naturally from experience.
  • A go-around is very much advised if you realise the flaps are incorrectly set at a low altitude where this cannot be fixed.

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