Operation
There are principally two types of overwing exits (excluding the full-sized door on the likes of the Boeing 747, which is not considered an overwing exit) in use on modern aircraft. The disposable hatch type exit is the most common, where the operator must first remove the hatch from its frame before disposing of it on the wing, away from the exit. The second type is the self-disposing hatch, found on more modern aircraft (such as the Boeing 737 Next Generation) which has been designed to both simplify the opening of the exit and to remove the hazard of the removed hatch blocking the exit. This is accomplished by the passengers simply pulling in and down on a handle recessed into the top of the door and initiating the exit's self-opening mechanism, whereby the door rotates up and out on a hinge at the top of the exit frame.
Depending on the height of the aircraft from the ground, an overwing exit may have an automatically inflating slide that is housed within the fuselage near to the exit(s). If the exit is opened the slide will automatically deploy and inflate to provide a means of evacuation from the wing to the ground. Only the slide on the same side of the aircraft as the open hatch will inflate. However, on aircraft where there is a pair of adjacent overwing exits on both sides of the aircraft (i.e. four in total), such as on some Boeing 767-300 variants, opening one of the pair of doors will deploy the slide. Should slide inflation fail, there is a manual inflation handle within the door frame of each exit (the location of which varies but is always indicated on the safety information card) which can be pulled to inflate the slide. Should this also fail the use of another exit should be sought.
Read more about this topic: Overwing Exits
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