1.   Even a knife used to cut meat at a restaurant might be passed on to a potential hijacker.

2.   First, it would add to the uncertainty potential hijackers face.

3.   The government and the airline industry want to persuade potential hijackers that marshals could be present aboard any flight.

4.   In recent weeks, the official said, the government issued a warning to airlines indicating potential hijackers might try to smuggle weapons in their shoes.

5.   Stun guns would supplement an ATA cockpit security initiative that includes reinforced cockpit doors as a temporary measure to foil potential hijackers.