Have you ever wondered about the possibility to open an aeroplane’s door during mid-flight? The short answer is, no and the science of physics is the reason behind it. On the ground before an aeroplane takes off, the door is locked by the cabin crews by a simple mechanical lock. However, when the plane is up in the air during flight, it requires a far more sophisticated yet simple process to keep the doors locked.
At the usual cruising altitude, the amount of oxygen in the air is far too little to support life. This is due to the low air pressure outside, which explains why oxygen masks drop down in cases of emergencies. To ensure normal breathing for passengers, the aircraft’s cabin is pressurized artificially to a lower altitude. This higher pressure effectively seals the door shut, which is why all aeroplane doors open inwards instead of outwards. The inner surface of the door is larger than the outside, causing the air pressure in the plane to push it firmly against the frame.
According to a professor from the University of Bath, the amount of force is about 5,500kg for each square meter of the door. Regardless of the strength of a person, the door is physically unable to be opened and is safely sealed. However, in the event of any large opening or crack in the aeroplane, the difference in pressure will suck anything unsecured right out. This unfortunate happening is why passengers are encouraged to keep their seat belts on during flights in such cases of emergencies.