Might be wrong, but I had heard it was possible to enter a pre planed flight path. Plane did a turn back over land before heading out to sea.

All air carrier flights are flown from shortly after takeoff to some point in the approach phase on a clearance that is entered in the flight management computer during pre-flight. Until the initial unplanned left turn the flight was likely flying in this manner. The turn itself could not have been executed on autopilot though. It was far too steep. The autopilot flight envelope protections would have limited the bank angle at that altitude. As it is, the plane was likely riding a fine line on the edge of a high altitude stall/spin scenario in order to execute that tight maneuver.

Might be wrong, but the left turn I believe you’re referring to happened when the plane left its planned flight path, at which point it descended to 23,000 feet and flew over land.

More like he asphyxiated everyone on the plane, including the rich heiress with her priceless jewelry and millions in cash, flew over a known location where he had previously towed a get-away boat, stole all of the other valuables on the plane, and skydived into the perfect crime.

Maybe he was related to D.B. Cooper?

So, basically Airport '77?