The latest technology to be employed in the unconstitutional search of people attempting to board an aircraft while exercising their right to travel is puffers:

'Puffers' add to airport security
1/12/2006 1:29 PM
By: Lisa Reyes, News 14 Carolina

CHARLOTTE, N.C. – Travelers at Charlotte/Douglas International Airport will soon see new security measures. High-tech machines to detect explosives will be located at three checkpoints.

The Transportation Security Administration says the imminent danger to aviation these days is explosives. TSA officials demonstrated devices called “explosive-detection trace portals” or “puffers” at the airport on Thursday.

The machines puff air on travelers to dislodge particles from their skin or clothing.

“It loosens particles that are attached to a person or his clothing, and those particles are analyzed by the machine for the presence of explosives,” said John Gartland of TSA.

The devices take about 20-25 seconds to check each passenger.

The TSA purchased the three machines through federal funding. They cost a little over $100,000, and about a 100 of them will be implemented in airports nationwide.

I agree that explosives is the biggest threat to safe airplane travel.  Other weapons such as guns and knives are of little use if someone wanted to bring the airplane down.  And if the user of such a weapon were intent on attacking people in the cabin they wouldn't make all that much progress before they were stopped by someone else in the cabin.  But a pound of explosives, about the size and weight of a pint of milk, in a tightly closed area like the cabin of an aircraft can do a lot of damage.  There is a Myth Busters episode on this very topic if you have any doubts.

In any case keeping explosives off of passenger airplanes is a good idea.  They aren't useful for self-defense in an aircabin enivornment, as the knives and handguns are, and they represent a significant hazard to the entire aircraft and people on the ground.  The problem is--How do you do it?  As I have explained before with the explosive sniffing wasps the problem is one of false positives if you try to detect improvised and/or "homemade" explosives.  And if you don't address those type of explosives you have a loophole any terrorist can waltz right through.  And the current explosives detection technology fails even on people that inadvertently contaminate their luggage.  If a skilled adversary were to be intent on bringing explosives on board a plane nothing short of a full search of everyone will be effective. So what's the solution? Use our limited resources on other things such as better intelligence as to who is a threat and interviews of passengers.  That will guard against both the known threats using existing weapons and the type of threats we haven't thought of yet.