Yesterday I've seen an A320 standing at the gate with flaps 1. While this question answers, why the flaps should be up, is there any reason to retract the flaps to 1 instead of up?

In addition it seems to apply only in high temperatures (30°C, and rising yesterday). As well in this pilot eyes video the FO confirms the temperature (31°C) before setting flaps to 1 as they taxi to the gate.

I've seen this only on the A320 (yesterday) and on the A330 (in the video). Does this apply only on Airbus aircraft or as well on others?

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    $\begingroup$ Never heard of anything like that in the 737. I'm entirely mystified as to what that might accomplish. $\endgroup$
    – Ralph J
    Jun 9, 2019 at 16:45
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    $\begingroup$ Are you positive that you saw the flaps, and not the slats? (Compare ymb1's answer, which discusses the slats.) $\endgroup$
    – user
    Jun 9, 2019 at 21:21
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    $\begingroup$ @aCVn: Config 1 selected on ground is called 1+F, comes with a bit of flaps. See aviation.stackexchange.com/q/51338/14897 $\endgroup$
    – user14897
    Jun 9, 2019 at 21:53

2 Answers 2


From the A320 Flight Crew Operating Manual (FCOM):

enter image description here

And the image to text:

On ground, hot weather conditions may cause overheating to be detected around the bleed ducts in the wings, resulting in “AIR L (R) WING LEAK” warnings. Such warnings may be avoided during transit by keeping the slats in Configuration 1 when the OAT is above 30 °C.

(Emphasis mine)

Basically it lets the leading edge anti-ice [hot air] leak sensors breathe, and not display a false positive.

Note that moving the lever to 1 from 0 or 2 at slow speeds (on ground) is called config 1+F, which deploys the flaps as well as the slats (see below).

enter image description here

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    $\begingroup$ So when do you retract the flaps to 0? When you leave the gate, are ready for takeoff, in the air, or ? $\endgroup$ Jun 9, 2019 at 21:11
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    $\begingroup$ @BobJarvis: It would depend on the takeoff configuration, it varies. More than config 1 could be needed. Flaps and slats are set for takeoff usually after pushback. And note the above applies to a transit, i.e., not the last day's flight. $\endgroup$
    – user14897
    Jun 9, 2019 at 21:45

I’ve been flying several types of Airbuses for the past decade and have never seen this kind of procedure before. There certainly is no such limitation in the manuals.

In general, it sometimes happen that there has been such a practice in a previous aircraft type the company has operated and these kind of procedures carry on as best practices or company procedures without any “real” reason.

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    $\begingroup$ Well, I stand corrected! See correct answer above. $\endgroup$
    – busdriver
    Jun 9, 2019 at 21:47
  • $\begingroup$ Thank you, extrapolating procedures from an aircraft model to another does not comply with the rules of the art. $\endgroup$
    – user40476
    Jun 10, 2019 at 9:33

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