Dtyjlui

I'm flying United, and at time of booking I can select my seat.

On one flight the aircraft is designated as a 777-200. The seat selection diagram shows a 3-4-3 seat layout, ABC-DEFG-HJK. At time of writing there are plenty of seats so I've happily picked an aisle seat in column G. The weird thing is that for the entire length of the Economy section of the place the F column is not selectable. It's not marked occupied, just greyed out.

Question: what does this imply? Could the airline be considering using a different plane? Is there any possibility that my aisle seat could be resignated a non-aisle seat? Seems too good to be true that I've effectively picked a seat with no neighbour.

Apparently some United 777-200s are configured with 3+3+3 seating in economy.

They may be keeping open the option of using one of those aircraft. Or perhaps their seat selector dialogue does not deal well with 3+3+3 at all.

You may find when you get your boarding card that your aisle seat is actually designated F rather than G, but there's probably not a significant risk that it won't be aisle.

If you are lucky it means that the plane actually has a 3-3-3 configuration. United has 5 versions of the 777-200, three of which have 3-3-3 and two have 3-4-3.

The 3-4-3 is a miserable experience. The seat width is only 17" or so whereas the average male shoulder width is about 18.25". You can't sit straight without jamming into your neighbors shoulders and so I often twist sideways which is murder on the back, especially on a long haul.

The 3-3-3 is quite comfortable and much preferred.

United Airlines has multiple versions seat layout on the 777-200, and are in the process of refitting more and more of their planes to the newer layouts.

Some of these layouts contain economy seats in a 3/3/3 format, with the seats labelled ABC-DEF-JKL (or on some, ABC-DEG-HJK, although these are very quickly disappearing). Others are a 3/4/3 layout, with seats ABC-DEFG-JKL.

For flights more than few days away, the airline may not be sure which specifically plane will be flying a route, so they won't be completely sure which of those seat layouts a flight might have. In order to handle this, United has been using the seat layout you describe - it shows as a 3/4/3 layout, but one of the seats is "blocked" and thus not selectable.

Once they defermine which type of layout will fly a specific route the seatmap will update, and either the 'G' seat will become available to be booked (it's a 3/4/3), or the G seat will disappear entirely (if it's a 3/3/3)