Originally Posted by
hugolover
When doors are placed into automatic I have understood this to mean that should the door be opened the slide will automatically deploy.
It stands to reason that the passenger operated over-wing exits will always cause a slide deployment if opened while the exit signs are illuminated and the door is not locked. I believe that on modern aircraft types the extinguishing of the illuminated exit sign means the door is locked and cannot be opened in flight (putting aside the impossibility of opening due to pressure blah blah).
Is my understanding correct?
You are touching on several different aspects of door operation here…
The general concept of the door being in "Automatic (or "Armed")" is correct. On main cabin type doors, the act of placing the door into Automatic, engages the girt bar from the slide into the girt bar brackets which are located on the door frame at the bottom, on the floor. This attaches the slide pack to the aircraft, so that, the action of opening the door (with powered assist on most aircraft types) will pull the slide pack from the bustle (the plastic "box" around the slide pack that you lot like to sit on or put your feet on, despite the copious signage saying not to…
) which then begins the inflation sequence.
On over wing exits, such as on the Airbus narrow body aircraft, I believe that the exits are armed at all times irrespective. Engineering are able to de-activate them for maintenance and the likes, but they are not able to be deactivated by the crew. Similarly, door 3 on the 767 is the same, it is ALWAYS armed which is why you never see crew at those doors taking any action when the command is given to place doors in manual or automatic etc.
It is slightly different on D2 and D3 on the A321, as the slide is stowed externally to the aircraft and the action/mechanism for inflating that is different.
In regard to the locking of doors and things like that. Certainly, on the 777, the door does LOCK during the take off roll, I believe it is at 80 knts, but I might be wrong on that one. And, as crew, if my hand is on the door at the time, you can feel it click into being locked. This would prevent it from being opened after that point. If I am honest, off the top of my head, I can't remember about the 747, I would have to look it up.
However, and I have had this conversation very recently with a passenger at D4 on the 787, above a certain altitude, it would be impossible based on the air pressure difference to open the door at all. The question of the light being illuminated or not, I do believe is nothing to do with doors and slides, it is purely to do with the landing gear being locked and down (exit lights on), retracted and locked (exit lights off) and don't remember from my short haul days, being told that they have any effect on the operation of doors and slides, and have not seen or heard any change to that effect, even on the new airbus deliveries.
Any more questions, feel free to ask.