What is the meaning of the 'XX' in amber below the 1 (in green) within the Slat Flap Trim section on the A350 PFD when the flaps are set to 1 with the correct speed (below 255kts)?

See picture attached. If the flaps would have failed, it would indicate XX without the 1. So, what else could this XX indicate? enter image description here


2 Answers 2


The number below the flap indication is not the position of the flaps/slats, but the position of the flap lever. When the lever is moved, the number becomes cyan indicating that the flaps/slats are in transit and when they have reached the selected position the number becomes green.

Edit: As per FCOM, there is no mention of amber XX indication for flap lever position at all. Checked in a simulator that total computer failure will not cause indication to turn XX.

  • $\begingroup$ This sounds quite reasonable. Do you have some references to support your claim? $\endgroup$
    – FreeMan
    Apr 19, 2019 at 19:58
  • $\begingroup$ I edited my answer. The reference is FCOM DSC-27-20-30. Don't know if there is one available online. Other buses have similar architecture and indications, so you might want to check those from www.smartcockpit.com, for example. $\endgroup$
    – busdriver
    Apr 19, 2019 at 20:21
  • $\begingroup$ Did you try holding the lever in between detents? $\endgroup$
    – user71659
    Apr 19, 2019 at 21:32

Thats your landing gear indication. The display unit is not receiving data for it. Normally when the gear is up nothing is shown.

  • 1
    $\begingroup$ You should add references and links to support your answer. Note that this links may provide further reading to dig into the subject of this question. $\endgroup$
    – Manu H
    Apr 19, 2019 at 10:53
  • 1
    $\begingroup$ Why so many downvotes on a post by a new contributer. I can't judge the correctness of the answer, it could very well be right. Yes, references should be included, but that's hardly a reason to downvote. If somebody has the evidence that this answer is faulty, they should leave a comment with the evidence. @A350Mechanic, welcome to aviation.stackexchange.com $\endgroup$
    – DeltaLima
    Apr 20, 2019 at 8:45

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