[Oliver Boliver Butt]

I would ban carry on totally as a first step.

I think the bigger problem is with maintenance personnel smuggling weapons or explosives on board. I haven't seen anything to indicate that this security hole has been plugged. Airports are crawling with low-paid laborers who have relatively easy access to cabins and cargo areas.

[OldFriend]

According to Jim Kallstrom, former FBI agent, all people with access to the planes have FBI background checks.