Amid all the talk of how the door locking system should or should not be modified (eg always rotating another person into the cockpit or whatever), I'm astonished that there's no discussion of having a backup radio system on the plane. One of the saddest things about this whole incident is the idea of the senior pilot futilely banging on the door with no way to get in, and no way to even communicate his predicament to the ground.
Allowing ground takeover of a plane in distress would bring numerous problems of its own and is probably not feasible to implement in the immediate future, but adding an extra radio would be technologically trivial, the protocols would be easy to implement, and it would allow witnesses to (apparent) crimes of this sort to pass information that might save lives or at least give investigators a head start instead of a 3 day delay.
Allowing ground takeover of a plane in distress would bring numerous problems of its own and is probably not feasible to implement in the immediate future, but adding an extra radio would be technologically trivial, the protocols would be easy to implement, and it would allow witnesses to (apparent) crimes of this sort to pass information that might save lives or at least give investigators a head start instead of a 3 day delay.