> Now - a strong person can do it when the plane is far enough up that it's very scary

Is this true? Some back of the napkin math: An airliner crusing at 30,000 feet is in air at about 0.3 ATM. Cabins are pressurized to about 0.8 ATM, so net air perssure is about 0.5 ATM. That's around 7 lbs/in^2. An airliner door is about 72"x42" for a total of around 3,000 in^2. So you need to be able to lift about 10 tons to open it. That would be a very strong person indeed.