HOW HIGH CAN THEY FLY?

It may be scant consolation to frequent flyers coping with Ouija-board ticket prices, jammed cabins and Munchkin-friendly coach seats, but the U.S. airline industry has reached cruising altitude. Last year it posted a $2.5 billion profit. Compare that with the $13 billion in losses the carriers had piled up since 1990--roughly equivalent to all the profits earned in the history of American commercial aviation--and the industry ought to be smiling, or at least unbuckling its seat belt and raising a $5 martini in a plastic cup.

Instead, the major carriers can see something potentially distressing: a swarm of alien aircraft invading...