Originally Posted by flyinbob
As I recall you can activate the slides manually with the door open. Anyone know if that is possible on the 737?
No, it is not. See post # 75 for an explanation of how door arming and the slide mechanism works. Bottom line: once the door is opened in the unarmed position, the slide cannot be deployed. The door has to be re-shut (which is difficult; see below), and then armed, and then opened again, before the slides will deploy.
If not, that would seem to me to be a bigger problem, since all the doors are disarmed before the main door opens. So any of those doomsday scenarios that have been presented here with regard to gate disasters would also apply to every plane on the ground.
I am not sure what you mean how that "would also apply to every plane on the ground." Other planes on the ground don't open their doors until they are parked at the gate with the jetway (or airstairs) attached, negating the need for slides. If the need for an evacuation arises while the plane is attached to the jetway, it is generally faster and easier to get people off through the jetway. If it is such an extreme emergency that people need to jump out of any opening, it is much easier to simply arm the other (closed) doors and then open them, then it is to try to close the door that was opened in the situation under discussion in order to arm it.
It is actually very difficult to close an airplane door from inside the airplane unless there is a way to get it started by first stepping outside onto a jetway or airstairs to get the door going. You would be surprised as this is something most people never think of, but one topic covered in F/A training is how to open and close an unarmed door, because closing it is trickier than it seems. In the case here it would have been very difficult to get the door closed to re-arm it if necessary since there would have been nothing to step onto outside the plane.