During takeoff in a B737-800 when there is predicted wind shear you can only use flaps 5,10 and 15.

Why is this? If possible to provide a reference for it.

  • 1
    $\begingroup$ I can't really give you the reference to my manuals, because they're proprietary to the company that I fly for... but the limitation you refer to isn't there. I doubt the planning software would use Flaps 25 if it had an option for something less, but I've seen a solution using Flaps 1 for such a case -- which isn't "predicted windshear" (you shouldn't take off if you predict that you will encounter windshear immediately after takeoff). What operation are you referring to that says that those settings either "are recommended" (question title) or "can only use" (question body)? $\endgroup$
    – Ralph J
    Nov 12 at 3:24
  • $\begingroup$ One thing: Lower flap settings have a larger speed margins - so a sudden change in airspeed will not so easily exceed the limits. $\endgroup$
    – tsg
    Nov 12 at 17:27
  • $\begingroup$ @MikeSowsun 737-800 $\endgroup$ Nov 14 at 23:23


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