I'm heavily leaning towards a deliberate action by the pilot. An expert on the Today Show made a few good points in that 1) the co-pilot had another way to get back in the cockpit, but the pilot intentionally locked it, and 2) the fact that the co-pilot lightly knocked didn't seem consistent with rapid decompression or catastrophic mechanical failure and 3) it's very common for one of the pilots to exit the cockpit once they reach cruising altitude, so pilot may have been waiting for this to happen. Another thing is that if the pilot was incapacitated, autopilot usually will fly the plane until it runs out of fuel (Flight 522 in Greece + Payne Stewart) vs. descending rapidly.
I just think it's way too coincidental.
I just think it's way too coincidental.
