[everdev]

A few theories:

1. The pilot waited until they we're alone in the cockpit then disabled all communications and locked the door. Possibly with a fake story over the intercom that kept people unsuspicious until away from land (diverting around some bad weather, etc.)

2. The pilot killed the co-pilot and then diverted the plane, same as above.

With a hijacking/ransom, the perps want to communicate, so I think that's out.

State actors is the only other one that makes sense to me, but it's still a murder-suicide by human hand.