Travel Etiquette Dos and Don'ts
How to Cope With a Space-Hogging Seatmate
…assert your territory early on: claim your overhead and under-seat space, and put the armrests down.
…be sensitive about passengers of size. Alert your flight attendant discreetly; you may be able to switch seats.
…resort to dirty looks, or subtle little pushes. Being passive-aggressive only escalates the problem.
…be greedy. Airplane etiquette says that the middle-seat passenger has rights to both inner armrests.