The Need to be Loved
Ted Striker is a pilot who, well, is terrified to fly. After returning from the war, he hasn't adjusted to society so well. To make things worse, his girlfriend Elaine has decided to leave him. Nonetheless, Ted isn't giving up on her, so he purchases a ticket from Los Angeles to Chicago upon the same airplane she works as a stewardess in order to reconcile their relationship. His need for love is the reason everyone lives as if he didn't get on the plane there would have been no one with any flying experience left.
Heightened Reality
Airplane! has become a classic comedy because of its use of heightened reality within the film. It isn't that the characters are acting absurd for the sake of humor, but that because their circumstances are heightened to the maximum degree they begin to act and react in ways that seem completely absurd. This approach is what creates the incredible comedy within the realistic elements of the film.
Disaster
The entire film is based on the idea that a disaster is impending, that no one will live. First, the co-pilots get wiped out from food poisoning, then the captain along with multiple passengers. This leaves no one to pilot the plane, except for an ex-war fighter pilot who is terrified of flying. It is the tension created by those who know disaster is coming keeping this knowledge from the passengers that drives the plot forward until there is nothing left to do but tell the truth to everyone on board: they are going to crash.
