Like Payne Stewart or the Nelson DeMille book (title forgotten but very good book) ? It’s possible but that would require, I think, a great deal of planning. It’s an awful big plane to ‘gas’, I think. Decompression with ‘jackers having their own air supply? More likely, just figure out a way to do it quickly. There’s so much I don’t know about this topic. If your theory is right then something else went wrong. After all, why go through all that trouble just to end up in the drink?
Just a theory that Gassing could be a trial run.
One person blocks access to the cockpit door, the other Gasses the Pilots.
Nightfall