Much better idea - how about remotely controlling the aircraft from the ground? That at least would completely negate the value of hijacking an aircraft as it wouldn't make the slightest difference to those on the ground - and unless it was blown up in mid air there's nothing that a hijacker could do to use it as an airborne weapon.
Of course, one slight drawback is that pilots would become surplus to requirements - but that's the price you've got to pay for safety!
