Just out of interest whilst travelling aboard a British Airways A320-232 G-MIDT on the 9.45 BA shuttle service (LGW-GLA) in seat 10F I noticed a placard above the window of seat 9F. Given this seat was two rows forward of an overwing exit I was wondering if it was related in any way.

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    $\begingroup$ From non authoritative sources online, it may indicate a window from where wing extensions (flaps, slats) are visible and can be checked visually (position and ice formation). Color is brown or black. $\endgroup$
    – mins
    Commented Jul 4, 2017 at 20:22
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    $\begingroup$ Hm, I am pretty sure I've already seen a question here about exactly the same marks in some other aircraft type. The search is not good enough to bring it up as related unfortunately. $\endgroup$
    – Jan Hudec
    Commented Jul 4, 2017 at 20:58
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    $\begingroup$ On quora.com someone said “The black triangle marks the location of what has been called "William Shatner's Seat," the seat with the clearest view of the wing.” $\endgroup$
    – PerlDuck
    Commented Jul 5, 2017 at 11:12
  • $\begingroup$ This video has the answer to your question. Cheers. $\endgroup$ Commented Jul 9, 2017 at 18:59

1 Answer 1


If there is a problem on-board and the crew is unsure about the condition of the aircraft, the triangle indicates what window should be used to inspect flaps, slats or engines or look out for icing.

This saves important time in case of an emergency, as the crew doesn't has to search the right window to look out.

For example if there is a failure of the flaps condition display, it has to be verified visually that the flaps are extended properly. From the window with the triangle, this can be seen:

Window View

Source, added square

Now the crew can compare the position of the flaps switch in the cockpit, with the actual extension of the flaps.

There are usually four of these triangles in the cabin. One to inspect the forward of the wing for icing, the slats and the engine on each side and one at the back of the wing for the flaps.

I have searched for cabin pictures and found this 360° cabin view by SAS.

The following picture shows the triangle on an Airbus A330 at the front of the wing. You can see a part of the engine through the window.

Front Triangle

Source, added squares

And this picture shows the rear triangle.

Rear Triangle

Source, added squares

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    $\begingroup$ But that sign looks like easily detachable. Any asshole can pry it off the plane. Also, are there similar signs in Boeing planes? $\endgroup$
    – Firee
    Commented Jul 6, 2017 at 16:30
  • $\begingroup$ Yes, in Boeing planes it's the exact same sign. And yes, I agree, it looks like it's only a sticker. Maybe it's part of the flight attendants cabin inspection to verify all triangles are intact. $\endgroup$ Commented Jul 6, 2017 at 17:16
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    $\begingroup$ Yes, @Firee, it could be pried off, but doing so would be pretty obvious to the cabin crew during flight and to surrounding passengers during (un)loading. The CC, I'm sure, would put a quick stop to it in-flight, and probably request police presence at the gate upon landing. One would hope that other passengers would, if not directly intervene with someone tampering with the aircraft, at least report it to the CC prior to take-off or when disembarking. I know I'd say something to the crew. $\endgroup$
    – FreeMan
    Commented Jul 7, 2017 at 14:01
  • $\begingroup$ Some decal adhesive is designed to be much more difficult to remove than typical decal adhesive. I was thinking about the kind of decals that are used for asset tags on expensive equipment: they are quite difficult to remove (and tamper-evident). If one really wanted to ensure that a decal stays in place, one could stick it down with epoxy and put a clear layer of epoxy over it as well. $\endgroup$
    – rclocher3
    Commented Nov 30, 2021 at 2:37

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