We do not attempt to open cabin doors whilst any positive differential pressure remains because in the first instance we probably couldn't. additionaly, any positive differential pressure is a hint that an engine may still be running and we may not want the doors opened. Theoreticaly, as the pressure decreases there comes a point at which we would be able to open the door with a tiny amount of positive diff and IF ! that occured the door would blow open very quickly and take us with it because we were holding onto it, NOT because there would be enough pressure to blow us out !
Those are the historical and very sensible reasons for not attempting to open doors with positive diff. Also don't forget the poor souls standing just outside the door !
PS. these are generalisations, armchair experts need not educate me about weight switches, throttles and outflow valves thank you.
Last edited by moonburn; 13th Jan 2012 at 16:02.
Reason: additional consideration