Many (too many) airline passengers have had a mental breakdown mid-flight. A select few of these passengers (reports indicate often those consuming large amounts of alcohol) decide to attempt to open the airplane’s door. These unfortunate few are met with a barrage of helpful crew and passengers who restrain and drag them away. Not one passenger has successfully opened a door, emergency exit, or window of an airliner mid-flight.
Why?
Two reasons, physics, and remote locking mechanisms.
Can you open an airplane door in flight? The short answer is no. Due to the differential pressure, there is internal pressure pushing approximately 1,100 pounds of force against each square foot of an airplane door from the inside, out. Additionally, the doors are mechanically locked automatically (and double-checked by the pilot) from the cockpit. The doors are not able to be opened unless the airplane is on the ground.
However, not all airplanes are pressurized like airliners are and not all doors are constructed equally.
In this article, we’re going to discuss exactly what it would require to open a door mid-flight, the mechanics of why airplane doors are designed the way they are, and exactly at what point in a flight the doors (and emergency exits) can be opened.
We’re also going to discuss what happens when a piece of fuselage does come off mid-flight and what type of aircraft it is completely possible to open the door anytime.
Table of Contents
Why airplane doors act as “plugs”
To understand why there is so much pressure on an airplane, we must first understand Boyle’s Law.
Boyle’s Law essentially states that all things being equal, the less pressure gas is under, the more volume it will take up.
A more detailed explanation of this process can be found here.
Boyle’s law applies to aviation like this: the higher off the ground you get, the less gravity there is, which means there is less air pressure.
When there is less air pressure, the air molecules are more spread out. When the air molecules are too spread out (anywhere above 12,000 feet above sea level), the human body begins to suffer oxygen deprivation.
At the cruising altitude of a 747 Airbus, for example, every breath of air provides about 25% of the oxygen received at sea level.
To compensate for this, airplanes pump compressed air from their jet engine compressors into the cabin, keeping the internal pressure to roughly equivalent what you’d experience at 8000 feet (about 4% less oxygen still, but not dangerous or damaging to the human body).
Because of this compressed air being forced into the cabin, at the normal cruising altitude of an airliner of 35,000 feet, there is about 8 pounds of pressure pushing on the skin of the aircraft from the inside out.
If the pressure is pushing outward, won’t the doors open easier?
They would, except for the fact that the vast majority of airplane doors open inward. Those that do open outward must first swing or slide in to operate.
Airline doors are known as plug doors and are shaped like (you guessed it) plugs, meaning the force of the internal pressure is pushing the door ‘in’ to its frame during flight.
The same concept applies to an airplane’s emergency exits, meaning that these are equally impossible to open mid-flight.
In addition to the design of the doors, they are also outfitted with locking mechanisms that operate automatically when the aircraft takes off. These use a combination of pressure locks (such as an inflatable seal) and metal latches to secure the door shut. They can only be manually overridden from the cockpit.
Consequences for trying to open an airplane door in-flight
We don’t have to go into hypotheticals on this, there are plenty of case studies.
If a passenger attempts to open a door or emergency exit in flight, they are in violation of airline and FAA regulations for tampering with the airplane. In the past, they have been immediately restrained until the flight lands, where they will then be detained.
The consequences vary on the situation and the airline. Many airlines will ban that customer from flying with them again. In the event of a turn-around, the customer may expect a bill covering the cost. One airline customer received a bill for $11,000 for just such an instance.
In the event that the action is interpreted as a willful attempt at violence, the person will be detained and charged criminally.
Due to airline procedures, if the attempt is interpreted as an act of terrorism, jets can be scrambled. One woman was arrested and fined over $100,000 after she attempted to force open an exit and continued to fight the flight crew yelling “I want everyone to die”. Jets were scrambled in this particular case.
Can doors or emergency exits be opened while on the ground?
The emergency exits are obviously there for a reason, so at what point are these able to open? The doors are not mechanically locked until just after takeoff, before reaching a high enough altitude to seriously disrupt cabin pressure in the event of one being opened.
They are again switched from automatic to manual mode upon landing. The flight crew must be in control of the emergency exits in the event they are needed quickly. They must also be in control of activating the emergency inflatable slides, which erupt with enough force to do serious damage to other aircraft or vehicles on the tarmac.
What would it take to open a door mid-flight?
We’ve already discussed the impossibility of doing so in a normal scenario, but what would it hypothetically take to open an airplane’s door mid-flight?
First, the cabin would need to be depressurized. This does happen from time to time, either from a slow leak or from major structural damage happening to the fuselage. If the leak were large enough for cabin pressure to equalize with outside air pressure, then technically the door could be opened… except for the latches.
The latches are controlled from the cockpit and are equipped with sensors that tell the pilots if there is any issue with the seal. These sensors are also activated by someone attempting to open the door latch.
So technically, if the pressure were equalized and the pilot manually unlocked the doors from the cockpit, then the doors could be opened mid-flight. Interestingly, at this point, it would be an undramatic event because the airplane is already depressurized, nothing would get sucked out of the door like in the movies.
What happens if a door-size chunk of fuselage comes loose in flight?
This has actually happened, and the results can be devastating, although they are recoverable. Serious structural damage to the fuselage causes an immediate ‘suction’ from the pressure differential equalizing. This will only last as long as it takes to equalize; in the case of a large hole, a few seconds. In those few seconds, any objects up to about a thousand pounds are likely to get sucked out of the plane.
Immediately upon a loss of cabin pressure, sensors are going to automatically release oxygen masks. Passengers and crew must put these on immediately to avoid hypoxia and blackout. Higher altitudes and sudden pressure differential (opposed to acclimating) can cause someone to pass out in less than a minute.
The pilots are going to immediately descend to around 8000 feet above sea level. In mountainous regions where this is not immediately possible, pilots will divert to a known flight path that will allow for the change in altitude.
The plane is now in danger of suffering further structural damage, although in past cases, there have been airplanes that were able to make a safe emergency landing.
General aviation
In this article, we’ve talked exclusively about airliners. However, in general aviation, many planes can open their doors mid-flight. It is common practice for those conducting parachute operations or dropping equipment. These planes are able to open them because their below the altitude necessary to pressurize the cabin, and without cabin pressure, they can open their doors no problem.
Opening the door mid-flight is even part of the emergency procedures for many small planes who experience engine failure. The idea is to open the doors while they’re still in the air so that in the event of a hard landing that may damage the airplane, the pilot will not be trapped inside inoperable doors.
Summary
It is not possible to open an airliner’s door while in mid-flight, despite many attempts in the past by passengers. This is due to a massive pressure differential and the design of airplane doors to open inward.
In the event a major breach does happen in the aircraft skin, serious results can occur, but it is still possible to recover the aircraft and land.
The consequences of attempting to open an airplane door are serious even if pointless. Punishments include fines that reach upwards of $100,000 and jail time.
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