An easy to understand explanation
After more than 30 years as an airline pilot, I constantly get a lot of questions from passengers about air travel and flying. One question seems to come up more often than others:
Can you open airplane cabin doors in flight?
The answer to that is a firm NO.
Do not worry about the door popping open if someone turns that door handle. The cabin door closes outwards, sealed to the body of the airplane. Cabin pressurization “pushes” on that door, keeping it shut solid, like a bank vault!
Emergency window exits work the same way.
To open the cabin door, the door first needs to move inward. Cabin pressure prevents that from happening.
Thus it is simply impossible to open that door in flight at cruising altitude.
Fear of the unknown adds fuel to the assumption
The passenger’s lack of knowledge or fear of the unknown compounds the fear around this subject. The news media is also guilty of sensationalizing relatively minor events.
That’s how they keep us glued to their news channel.
Given, an initial harmless event in an airplane has the potential for developing into a chain of events. This, in turn, may turn that situation into a serious situation.
But someone trying to open a cabin door in flight is not one of those chains of events progressing to the door actually opening!
Consequences of trying to open a door in flight
A passenger trying to open a door at cruising altitude is not an emergency, but rather, an incident. It is not going to kill anyone, but it is an incident which qualifies as “Interfering with the safety of flight”, a Federal crime.
So, the consequences of trying to open a door in flight are not the door being in danger of coming open.
Rather it has consequences for the perpetrator. Law enforcement may greet him or her on the ground after arrival.
The operation of the door In a house versus an airplane cabin door
People tend to associate the opening of the door of an airplane cabin door with the operation of the door in their home.
But the door of a pressurized jet in flight does NOT work the way your door at home works.
Scenario A: You’re coming home
You insert the key to unlock your door and you turn the knob. Then you push the door open and you walk in.
Now, imagine an 18-wheel truck was located on the other side of your door. The gigantic truck is blocking your door completely, keeping it shut against your opening direction.
Would you be able to open that door?
Of course not.
Scenario B: You’re inside an airplane at 37,000 feet
Your airplane cabin door represents the door of your home. The cabin door handle represents the key and the doorknob you use to unlock and go through your door at home.
This real thing, called cabin pressure has now replaced the role of that 18-wheel truck.
Some guy, a fellow passenger, approaches the door while you are enjoying your flight, eating your chicken served in that infamous plastic tray, perhaps watching a movie.
Then you notice… The guy grabs and unlocks the door handle.
OMG, someone is opening the door!
What happens from here maybe dramatic, but the drama will NOT proceed to the door actually opening…
A fellow passenger may decide to knock the perpetrator onto the floor.
Or you may witness how a well-disguised Air Marshall on board gets up from the seat to handcuff him.
A flight attendant may break a wine bottle over the guy’s head if the situation escalates into a temper tantrum on behalf of the perpetrator.
You will be happily disappointed if you expect drama from the door actually opening!
But why did the cabin door not open, like the door in your house? After all, that guy managed to move the locking handle.
Why you cannot open cabin doors or emergency window exits in flight
Remember that 18-wheel heavy truck preventing you from opening the door in your house? Now, think of that truck as the airplane cabin pressure.
If a person could physically open that door, he or she would have to have the strength to counteract that 18-wheeler truck pushing on your door, keeping it shut!
An actual example
Let’s say you’re flying on a Boeing 767 and someone tries to open the cabin door at 37,000 feet. The cabin is pressurized at 6.5 pounds of air pressure per square inch.
A B767 door is approximately 74 inches by 42 inches (1.88m by 1.07m). That means 3,108 square inches of pressure is being exerted on that door to keep it shut!
6.5 pounds of pressure per square inch multiplied by 3,108 square inches of that door means that it takes 20,202 pounds of brute human pulling force to pry that door open inflight!
Is that possible?
Of course not.
But how about the mechanical locks the door handle is attached to?
Moving the door handle or the latching mechanism only releases mechanical-type locks.
The purpose of these locks is to keep the doors locked when the airplane is not pressurized or on the ground.
We need the mechanical locks to keep the door secured shut when not pressurized.
It also allows you to open the doors and the emergency over-wing exits during a ground emergency, or deplaning through the doors on the ground.
Operation of the door mechanics also leads to the activation of the emergency slides, when armed.
Of course, the mechanical locks also work in the air.
But they no longer function as the principal means of keeping the doors securely shut.
Cabin pressurization assumes the role as “the principal safety guardian of the door” in flight.
How does an airplane maintain the cabin pressure keeping the door safely shut in flight?
Airplanes have a system that incorporates valves on the body of the airplane to close and open automatically.
These valves control cabin pressure during the different phases of your flight.
The engines are continuously producing compressed cabin air.
After that, the air is conditioned and turned into pressurized breathable, temperature-controlled air.
After cycling through the cabin a little bit of that compressed air is allowed to escape through these outflow valves to maintain the desired pressurization inside the cabin.
Newer jets, such as the Boeing 787, are constructed differently.
Here the cabin air is even more dense, with a greater level of oxygen saturation. Our bodies benefit by not having to work as hard to oxygenate the blood and sustain itself.
The usual very dry air in the cabin has also been greatly improved in the newer airplanes.
The air has gotten more humid.
By the way, since the air is denser in these newer airplanes: how does that affect the inability to open the door in flight?
Dense air is what keeps the door shut and sealed, so that is great!
Cabin pressure goes to work immediately when you take off.
Sensors in the wheels tell the airplane that you are no longer on the ground.
As you climb the cabin pressure per square inch also gets higher.
That ensures your safety from someone being able to open the door in flight.
Knowledge breeds confidence
So, the next time you see that news flash about yet another passenger trying to open a door in flight you can consider yourself an expert on the subject.
Passenger opening the cabin door at cruise altitude???
Nope, it’s just not possible.