Originally Posted by
GUWonder
History shows that some wannabe homicidal maniacs have held back (or wanted to hold back on) detonating an explosive device on earlier flights so as to have the IED go off on a connecting flight being targeted.
Just as a sideline and on the more general topic of threat levels in aviation that's an interesting point actually: Given the laxity of security in the US and the widespread availability of components and knowledge for bomb making in the US, it can be argued that having someone fly and deposit an explosive on a flight would be an ideal vector for someone wanting to harm aviation. You don't require someone to make that psychological "leap" to suicide bombing: just book a ticket, place the bomb under the seat in front, get off and let the plane carry on to it's next flight (or some time in the future) when it goes bang via a simply timer. There's history of that method being used, yet it clearly isn't being pursued in the last decade or two. Closest would be the printer cartridge efforts from a few years ago - which is actually
easier to protect against for security services. If they're paying attention.
The only rational conclusion is that the threat itself doesn't really exist in any meaningful sense.