With more people flying, there's also been a noticeable increase of in-flight fights. Inspired by news of a physical altercation resulting from armrest conflict, Jason Torchinsky reminds us of the sane rules for armrest allotment that travelers with even a modicum of experience or common sense have been abiding by for quite some time. In summary, the aisle seat passenger the outside armrest. The window seat passenger gets the window armrest. And the middle seat?
This seat gets the both armrests. The center seat has none of the benefits of the aisle or window, and as such is compensated with the use of both the armrests that border the seat.
It is generally agreed to be the worst seat in the row, and as such deserves the compensatory extra armrest.
"These Are The Definitive Rules For Airplane Armrest Allocation" (Jalopnik)