[Retired Chemist]

Fox is reporting that there might have been an oxygen problem that caused the pilots to pass out. ( Remember Payne Streart's plane?)

[bill1952]

That makes sense, although they would have had to have been well past "passed out," or they would have regained consciousness under 10,000 feet.

In Steward's case, the plane depressurized but continued to fly high on autopilot until it ran out of fuel.

[festus]

Fox is reporting that there might have been an oxygen problem that caused the pilots to pass out. ( Remember Payne Streart's plane?)

Keep in mind that the highest point in Greece is Mt Olypus which is not at the 10,000 foot level ( more like 9500 feet ). Below 10,000 feet you do not need a presurized cabin.

Since the plane hit the mountains it must have been flying lower than that. It is possible the plane lost altitude first but not if it was on autopilot.