Airline Security
In Educated Guesswork, Eric Rescorla writes about one way tickets and the search criteria.
The CAPPS program was created by Northwest airlines, who set the criteria for inclusion. They included one way tickets to enforce their bizarre pricing schemes. This is the same reason they started asking for ID: to cut down on the resale of the other half of a round-trip ticket, which cost the same as a one-way.
CAPPS, incidentally, has been renamed the “free wheelchairs for paraplegic children” program, to make it harder to argue against, and to get around a congressional mandate that the program not be deployed until someone actually thinks it through.
In his comment, Kevin Dick gets it mostly right–there are other items that you want to keep off the planes (pepper spray, for example), but the right technique in a free society involves enabling passengers to fight for their lives, and fortifying the flight deck. There’s a lot that could be done that hasn’t been. For example, consider an “airlock” system, with two doors at the front of the plane, with a restroom inside. The doors open one at a time. There may be an air marshall inside. (A curtain prevents anyone from seeing.) Now hijackers need to get through two doors. They can’t storm the cockpit while the pilots are being fed or using the restroom. This is very expensive. It would require a new bathroom for the high-revenue business travelers up front. It makes a section of plane unusable for reveune generation. But it is entirely free of civil liberties implications for fliers.