The prospect of a terrorist taking over an airplane is never a pleasant one, and given that today a plane can almost pilot itself
, all that a potential hijacker has to do is get into the airplane's computers--he doesn't even need to be on the actual airplane.
This is well within the realm of possibility; there's going to be a demonstration on how to remotely hack an airplane
at an upcoming security conference. This is apparently a particular worry for higher-end corporate jets, which may be more vulnerable
than traditional commercial jets because they offer easier external access to internal computer systems--great for fast communication, but also for hackers.
Surely air traffic control is safe? Afraid not. Past security conferences have demonstrated that the future air traffic control console can be overwhelmed by false signals
The threat level
The technological vulnerabilities are certainly worrisome, but airplanes really haven't been a popular terrorism target since 2001. Just because something is a passe target doesn't mean we should forget about it. But it makes more sense to understand what kinds of attacks terrorists like to do, and protect against those, rather than ones they could conceivably
do but haven't done. These days, the popular attacks mostly involve bombs on the ground