Air O is a Japanese airline in Kill bill and Death Proof. Unlike most real life airline companies who don't allow passengers to carry weapons onboard, Air O lets katana owners bring their swords with them in the cabin. First-class seats even have built-in sword holders for this purpose. Its known routes include flying to El Paso, Okinawa, and Tokyo. It is an international airline. It is unknown what the O in Air O stands for.
There is known to be other aircraft, but only an Air O 747 is seen.