Have you noticed them?
Aircraft manufacturers pay acute attention to aerodynamics. Each airplane wing is designed to be as smooth as possible to make the aircraft fly efficiently. With this in mind, passengers may be confused when they look out at the wings and notice two small yellow bumps.
These small yellow bumps definitely affect air as it travels over the wings — however any loss in aerodynamics is well worth it as these tiny features are a crucial safety aspect of many commercial aircraft.
The exact number of hooks and distance out on the wing may vary from plane to plane, but generally there is a double hook about one-third of the way out from the door. In the event of a water landing, these small hooks help passengers safely exit the aircraft, one pilot explained in a video.
Once the passengers in the emergency exit row open the door, an escape slide at the back end of the wing automatically deploys. The other passengers will exit through this door, walk across the wing and slide away from the plane.
During a water landing, the wings are likely to be wet and very slippery, making it difficult to safely reach the slide.
If cabin crew must facilitate an emergency exit over the wing, called and "overwing exit," they will pull out ropes from safety lockers above the emergency exit row. Once the exit is open, cabin crew secure one end of the rope in the door frame while the other end of the rope is fed onto the wing and through the small yellow hooks.
Passengers can use this rope to steady themselves on the wing as they make their way toward the inflatable exit slide.
If passengers must also wait on life rafts for rescue, crew can use the ropes and emergency hooks to tether the rafts to the plane.