"What should you do if your door is not properly latched and pops open in-flight?"
- Francis S.
“A cabin door popping open just after takeoff can be a very distracting event and has been the cause of several accidents.
The natural pilot action is to attempt to get the door closed as soon as possible and this is exactly the wrong thing to do. The most important thing is to maintain aircraft control. In my experience, it is almost impossible to get an open door closed in flight, so don’t get distracted trying.
In most airplanes, the door will only open a few inches as there is a lot of airflow preventing it from opening too far. There may be some slight loss of performance but aircraft control should not be a problem. If your POH has a procedure, follow it. In general, avoid high-speed, and return and land using normal procedures.
In the worst case scenario, it is possible (but not probable) that the door could come off and hit something on the tail. This is a very low probability, but that could cause controllability problems. So there is good reason to maintain aircraft control and keep the speed from becoming excessive.
So if this happens to you, give up on the idea of getting the door closed. Return, land and close the door on the ground.”
Wally provides useful tips like this in our Airmanship Series