sky marshalls, cockpit doors that cant be opened profiling, all those are probably good idea and ought to be implemented. Pilots are now discussing countermeasures such as depressurizing the cabin partially, making evasive manoeouvers that would throw the plane around and unless you were sitting with a seatbelt you would be thrown around, even on a sharp descent you would probably lose your footing.

There is a system whereby an autopilot will be engaged if there is no voice from the pilot after a 20min period.

My neighbour says his niece just flew from Newcastle to Hamburg and was allowed no carryons other than a plastic envelope containing her passport and money.

You might say a lot of this is closing the barn door after the horse is gone, The fact that 4 planes were hijacked and possibly a 5th one was planned but was prevented because of the air emergency indicates that the hijackers knew they would have one chance and one chance only to pull this off, as security would be extremely tight afterwards it would be unlikely to occur again. (but they would probably choose something else - something equally frightening)

What surprises me is that the authorities didnt see it coming. There are think tanks whose purpose is to come up with terrorist scenarios, but most terrorist incidents in the past had a clear motive, ie. release of other prisoners etc. these terrorists have no motive that is clear to us other than to instill terror and disrupt our way of life. No one has claimed responsibility, and yet the targets are so symbolic of America and the Western world. It is chilling.