Repeat after me three times: An open door can’t hurt me, but it can kill me if I let it distract me from flying the airplane.
Good. Repetition helps recall, as you know. And, so too, does understanding what you are repeating.
I’m sure your subconscious mind just conjured cups, napkins, clothing, and cellphones being sucked into a stratospheric whirlwind while the screams of terrified passengers are ripped from their lungs. Well, that simply cannot happen in nonpressurized airplanes, and it rarely happens that way outside of Hollywood in any form of aviation.
So, what happens when our training airplane’s door opens in flight? Nothing. While there might be a small Bernoulli low outside the door from the flow of air along the fuselage, it doesn’t change the aircraft’s handling in any serious way and it is not an emergency. In fact, the relative wind of the airplane’s forward motion is strong enough that it pushes a forward-hinged door almost closed again. It won’t be open, so much as cracked. Things might get a little bit more noisy inside the airplane, and loose charts and notes may swirl around, but that’s it. And as you’re safely strapped in, you can’t fall out.
Why would a door come open in flight? Occasionally the mechanism breaks or fails, but usually it’s because someone didn’t close it properly. Some airplane doors are tricky. Others are stubborn. And they vary from model to model, so procedures that work on one type won’t necessarily work on another.
But because the most common cause of doors opening is a failure to close them properly, when doors do open, it tends to be on—or right after—takeoff. The proper procedure is to take a mildly breezy lap around the pattern, land, and close the darn thing properly.
So how can it kill you? If you get distracted trying to close the door in flight while operating at low altitude. It’s the loss of situational awareness, followed by a loss of control, that can kill you while you deal with something that can’t hurt you.
And that pretty much closes the door on this tip.