If we can't afford sky marshalls, how about allowing cops to fly free? Now, maybe not all cops, but those with a relatively clean record (complaints) and at least 5 years on the job.

It's worked on the LIRR on Long Island after Colin Ferguson went on a shooting rampage.

Then again, I never dismissed out of hand, Archie's Bunker suggestion of arming eveyone on board (only kidding)