Is Flap down command is same as setting the flap angle to 25degrees. Recently I am reading the information related to Flap and got confused with different terminology. Trying to get relation between flap angle and Down/Up commands. On the same line I read that EGPWS uses the flap down signal, and why EGPWS need this signal.

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    $\begingroup$ It isn’t clear to me what you are asking. Most aircraft, even simple GA airplanes, have several different angles they can be set at. So, for example if the flaps were up, you could command them down to 10 degrees, or 25 if there was such an increment on your airplane. I don’t know what this has to do with EGPWS other than the tone might be inhibited with flaps down under the assumption that landing is intended. What specific airplane are you asking about? $\endgroup$ – Michael Hall Jun 9 at 15:59
  • $\begingroup$ Hi @MichaelHall, just trying to understand the impact of flap signal on EGPWS behavior and at the same wanted to get my self clarity on what angles are flaps down and up. Thank you for the information. Now I got clarity. $\endgroup$ – Balaramakrishna Rachumallu Jun 16 at 15:17
  • $\begingroup$ Hi @ManuH I corrected the tittle, thanks for pointing that out. $\endgroup$ – Balaramakrishna Rachumallu Jun 16 at 15:18
  • $\begingroup$ Thanks, I was able to discern that from the answer. Freeman is smarter than me! $\endgroup$ – Michael Hall Jun 16 at 15:28

Depending on the aircraft, flaps can be set at one of several different settings anywhere from 5° to 40° (or more, from what I understand). All of these settings are considered "down". (The exact flap angle depends on the aircraft, current weight, air temp and other factors and more than one is "appropriate" for take off or landing depending on these conditions.)

The EGPWS (Enhanced Ground Proximity Warning System) needs to know whether flaps are up or down (among other things) so that it knows if the plane is configured for landing. If you're 50' AGL and configured for landing, the EGPWS is going to assume that your intent is to land, so it won't tell you "pull up". If you're not configured for landing, but you're still 50' AGL, it's going to yell at you in an attempt to keep you from flying into the ground.

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  • $\begingroup$ Thank you @FreeMan for the answer, this clarified my doubts. $\endgroup$ – Balaramakrishna Rachumallu Jun 16 at 15:18

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