I recently flew in a Boeing 737-800 in Thailand. My seat was 53K so I thought: "That's a big plane for such small domestic travel." When I entered the plane however I discovered that seats start at number 31, so 53 was actually the 22nd row instead of the 53rd.

But even stranger was that the letters on one side were A,B,C but on the other side were H,J,K (not only skipping several letters but not even consecutive letters). The plane was a standard middle corridor with 3 seats in each side.

Is there any logic in numbering seats like this?

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    $\begingroup$ Welcome to Av.SE. This question may be a better fit on Travel.SE, since they're more focused on the "passenger" side of things, while this forum is more focused on the "pilot" side. That said, let's see if you get a good answer here before having a moderator migrate the question. $\endgroup$
    – Ralph J
    Commented Apr 5, 2019 at 5:49
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    $\begingroup$ This is a good question and answerable but i feel it more belongs to travel.se $\endgroup$
    – vasin1987
    Commented Apr 5, 2019 at 6:24

1 Answer 1


I would imagine this is related to having a common factor across all fleet types, eg I would imagine that Economy class across all aircraft types, both Narrow and Widebody, start at 31.

Similarly if you booked an 'A' or 'K' seat you would be assured of a window, or a 'C' / 'D' seat would always be an aisle in the window block.

HJK is not consecutive because I and O are generally unused where they can be confused with the numbers 1 and 0(zero).

  • $\begingroup$ Makes sense. Thanks $\endgroup$
    – Elerium115
    Commented Apr 5, 2019 at 13:50

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