Commercial airplanes do not need keys to start. The cabin doors and engines of commercial airplanes do not require keys to open or start. Cabin doors are usually opened manually or electrically by ground crew, and engines are started by pilots through buttons on the computer system panel.
There are a few reasons for this. First, commercial airplanes are usually parked at airports, which are under tight security. Second, starting a commercial airplane engine requires a series of complex procedures and professional knowledge and skills. Even if someone could enter the aircraft, it would be difficult for them to start it.
Some small aircraft, such as private planes, may be equipped with keys to prevent theft. However, for most commercial airplanes, keys are simply not necessary.
