When the emergency doors over the wings are opened do the wings automatically lower themselves, to allow passengers to slide and reach the ground? Or does the pilot have to do it from the cockpit?
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Wings are static.
The wings do not move in response to emergency door opening. There is no requirement regarding position of flaps, in most cases involving an emergency evacuation after landing, flaps are likely to be extended, but I don't think this is guaranteed.
Evacuation assistance
On commercial transport aircraft, there are marked routes on the wing for passengers and, if the exit point is more than 6ft from the ground, there are self-inflating slides that allow passengers to reach the ground.
Image from video by "Airline_Alex"
Evacuation on water
The inflated slides also work as life-rafts in the event that the aircraft comes to rest in water and has to be evacuated. Generally this applies only to slides at main exits, over-wing exits have slides that are not designed to be used in this way.
Regulations
The regulations in the USA say
Each passenger-carrying landplane emergency exit (other than over-the-wing) that is more that 6 feet from the ground with the airplane on the ground and the landing gear extended must have an approved means to assist the occupants in descending to the ground.
The manufacturer must demonstrate that they can evacuate all passengers and crew to the ground within 90 seconds using only half the emergency exits.
This applies to aircraft capable of carrying more than 44 passengers.
Variations in arrangements by aircraft
Not all aircraft need overwing exits and slides. Here are some B757 variants
From CRJ Resets
Boeing 737
As commenters have noted, the 737 does not have self-inflating slides for its over-wing exits.
The 737 system does not always work very well
Passengers climbed onto both wings, which were slippery due to the rain, but were able to see the markings indicating the direction of movement. It was difficult to see the ground in the dark and some passengers were not aware that they should slide down the flap surfaces. Others expected to find an escape slide. On the left wing, some passengers slid down onto the ground and assisted others. On the right wing, fewer people slid down to the ground, while others re‑entered the cabin and exited it using door escape slides when it was apparent that there were no visible signs of danger.
- from AAIB report
RedGrittyBrick
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@Firee I believe that every exit door will have a slide attached so that if the plane makes an emergency landing, passengers & crew will be able to safely make it to the ground - it can be a pretty significant drop. – FreeMan Sep 01 '15 at 14:40
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@Federico; Thanks, that video depicted it very well. However, isn't there a risk of the blast from the engines in this scenario? – Firee Sep 01 '15 at 16:21
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10@Firee It is standard practice to shut off the engines after an emergency landing (assuming they're still running after everything stops moving). Generally the cabin crew will not begin the evacuation until that has been accomplished as having your passengers survive an emergency landing only to be swallowed up or blown away by the engines makes for really bad press. – voretaq7 Sep 01 '15 at 16:36
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2@Firee jetblast (and passengers getting sucked in) is an issue with the other exits as well. that's why they get shut down. – ratchet freak Sep 01 '15 at 18:24
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8B737 does not have slides for its overwing exits and passengers are expected to slide down the flaps, which is I suppose the reason for the question. – Jan Hudec Sep 01 '15 at 19:13
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Note that shutting down the engines may not always be possible. In the QF32 accident, shrapnel from the exploded engine severed the control lines to the still running one, and as a result, with no control inputs to tell it otherwise, the FADEC kept it running at the last power settings. The fire brigade had to shut it down by shooting foam directly into the intake. – Jörg W Mittag Sep 01 '15 at 23:15
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@JanHudec: You are right. If you read my comments in the question, I do mention that the image on the safety card did not show any slide. – Firee Sep 02 '15 at 07:58
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@JörgWMittag: The QF32 accident is really an interesting read. I wonder, couldn't they have evacuated the passengers from the other side of the aircraft, where the engines had completely stopped, or is it a danger to be anywhere near a plane with one of its engines running – Firee Sep 02 '15 at 08:15
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@Firee: They probably could have evacuated, if they really wanted to. But why? The aircraft had safely landed, all fires were extinguished. Evacuating via the slides pretty much always leads to broken bones, so that's definitely worse than sitting around for an hour. They could have brought airstairs to the port side exits and evacuated the passengers directly into shuttle busses, making sure nobody wanders around the airplane, but still, why risk it? They were probably sitting there drinking coffee, feasting on delicious airline food, and there was no real danger. – Jörg W Mittag Sep 02 '15 at 08:23
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@Firee: Actually, I just re-watched the episode, and it turns out, they did evacuate with the outboard engine still running. The reason they didn't evacuate before was that the aircraft was still leaking fuel onto the runway, not because of the running engine. They evacuated via stairs (which is much safer than slides) as soon as all the fuel had been covered in firefighting foam. In the archive footage you can see firefighters walk around the aircraft quite close to the engine while attempting to "shoot it out". – Jörg W Mittag Sep 02 '15 at 14:33
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@JörgWMittag : I just watched it too on YT. What I was amazed, was the ability of the engine to withstand so much water spray and still keep running. They explained that the engine is designed to withstand torrential rains. Just curious as to how much amount of water/rain could those engines withstand. – Firee Sep 02 '15 at 16:03
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@Firee: You should ask another question, engine water ingestion is not sufficiently related to this Q about over-wing-exits. Also ... [chat]. – RedGrittyBrick Sep 02 '15 at 16:07
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There are no transport aircraft where the wings would be movable.
However if you meant flaps, the question would make sense.
In most aircraft the overwing exits are equipped with inflatable slides that inflate aft over the wing trailing edge (see the image in the other answer). However in some aircraft it is indeed intended that the escaping persons will slide down the flaps, most notably on Boeing 737:
(copied from this answer, the original source seems unfortunately dead)
No, the flaps don't move automatically. The pilots have to extend them. Worse, the flaps require power to move and they move rather slowly, so they may not extend all the way due to lack of time or failure of the necessary systems.
I've seen some incident report involving evacuation where it was mentioned that the flaps were not extended all the way down due to lack of time, but I don't remember enough details to find the reference now.
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The dead source is from here where they have a 737-700/-800 flight safety card currently for sale. – FreeMan Sep 01 '15 at 20:25
does the wings outside automatically lower themselves, to allow passengers to slide and reach the ground. Or does the pilot have to do it from the cockpit- bad assumption. Neither is true. Do you mean lower the flaps? – Simon Sep 01 '15 at 11:16The wings cannot be moved, either automatically, or from the cockpit. What do you mean "both"?How would I know the wings cannot be moved, hence I asked the question. Also, if you read my comments, my assumption is based on the image of the safety card, in which the wing had almost touched the ground. – Firee Sep 01 '15 at 14:14