A little story for those that are worried about doors opening in flight.
A320 nightstop. Aircraft is left on the ground service bus, all the doors are closed and a ground air heater is plugged in.
The temp is around M15, and the arriving crew have read their FCOM and without asking the engineer have pushed the ditching switch.
In the morning the new crew come down the jetty. The door is closed, and the cabin pressure warning light in the door is flashing. The dispatcher, who usually opens the door, says that he can't open it. The Captain says that the flashing light MUST be a false warning and heaves up the lever to open the door. The FO catches him as he is propelled across the jetty by the door opening explosively.
He should have heard the hissing noise as the air escapes past the door seals, obeyed the warning light, and asked the ground crew to turn off the heater.
The little ground heater can pressurise the aircraft enough to nearly seal the door closed.