What's the etiquette on armrests? On the occasions that I've had to endure a middle economy seat (never by choice), my window and aisle travellers seem to assume both middle armrests are theirs, even extending to elbows straying into the centre seat space. I know economy seating can be cramped for even a small person, but the middle seat goes from bad to horrible if there's no armrest on either side and encroaching neighbours.