As I'm sure others have said, arming flight attendants or hiring armed guards may only arm the hijackers with more powerfull weapons. As I am a pilot in training, I couldn't imagine if the cockpit were locked and I was told to open it or passengers would be killed.

The only thing that I think could and should be done(at least for larger planes) is a bit of programming to the aircrafts computers. Most large planes are push button operated. Meaning taking off and landing are pretty much controlled by the computer. In the event of a hijacking, the pilot is supposed to contact the tower and change his transponder to 7700(emergency signal). I'm not positive, but I believe there is also the equivalent to a "silent alarm" button, like a bank, that alerts the tower of a hijacking. This is not enough. What needs to happen, is if this button is pressed, the control tower takes control of the aircraft and puts it into a circle pattern.

What this would mean(and let the hijackers know this before hand!) is that the plane would be uncontrollable to the pilot or anybody else on that plane. Without computer control, it would be impossible to created the nightmare that happened to the WTC Towers and the Pentagon. While I don't like the idea of letting the computer land an aircraft, it has been done before with some success and in a time of need ,such as those that just occured, I wouldn't mind taking the chance. Alright, I'm tired and rambling so I'll leave you to think about this. Bottom line, no weapons on board, no locked cockpit, NO CONTROL in the plane after hijackers are suspected(under any circumstance: even if the captain radios the tower and tells them its a false alarm)

-touch