Recently TSA has begun to allow passengers to bring small knifes and nail clippers aboard airliners again. This is a very small step in the right direction. When air screeners take away any object that could be remotely contrued as a weapon, it inconveinces passengers, detering even the most law abding citizen from traveling by air. This is causing a lot of problems for an already troubled industry.
The fact of the matter is that there is only one kind of weapon that can be plausibly used to hijack a plane in the post 9/11 world: Explosives. Boxcutters will not work anymore, since passengers can be expected to defend themselves now that we know that anyone who trys to kill or interfere with the pilot probably wants to crash the plane. Gun related hijackings have ceased since the installation of metal detectors in airports. Terrorists now know that they have to be able kill everyone on board, only a bomb would be enough to keep everyone quiet and in their seats.
And even the use of explosives could prove difficult. Once upon a time, Semtex was the explosive of choice for terrorist since it had no smell. Now the Czechs have been nice enough to add chemical tags and scents to Semtex, and they have also stopped exporting it. All batches of the unscented variety are no longer usable since the stuff has a 20 year shelf life. Anything now should be detectable by chemical sniffers. Rather than spending $100, 000 a year per airport on five air screeners who can only expediantly pat down one in 10 passengers, the money should be spent on the one time cost of one chemical sniffer for every airport. This way, every passenger will get checked, instead of just elderly grandmothers who fit a profile.
There have been no terrorist incidents on domestic flights in almost 4 years. Only one terrorist incident has occured on a flight headed for the US since 9/11, and it was stopped by two observant flight attendants. It may be the case that al Qaeda has given up on airliners and is starting to look into other targets. Let's spent our homeland security dollars accordingly.