> Even at only 1500 feet alititude where the pressure
> differential is only
> about 0.3 psi, this will still result in 900 pounds of force
> on a typical
> 747 door.  At higher altitudes, typical pressure differences get up to
> around 8 psi, and that same door will then feel a force of
> around 24,000
> pounds, at which point the phrase "sucked out" will be more
> than appropriate
> should the door fail.

We had two-phase latches on the watertight doors on Trident subs for the
same reason; a half-psi differential between two compartments (which was
easy to achieve) produced over 1800 pounds of force on the door, so catching
the opening door with your face was considered poor form.