[festus]

Since Greece has no mountains over 10,000 feet,

I checked that out and you are right. The highest point is Mt. Olympus which is 2917 meters and if I did my math right thats 9521 feet.

Since decompression would not be a problem at or below 10,000 feet what happened ?

[longtermmemmory]

everyone gets knocked out at altitude and then the autopilot takes the plane dutifully down to the landing altitude. At 10,000 feet people start to regain conciousness.