Definition
The tendency of an aircraft in a steep turn to continue rolling into a steeper bank without further control input from the pilot. This occurs because the outer wing, traveling on a larger radius, moves faster through the air than the inner wing, generating more lift on the outside of the turn and rolling the aircraft further into the bank.
Plain English
When an aircraft is in a steep turn, it wants to keep rolling more and more into the turn on its own. The pilot has to actively hold the wings against the roll to keep the bank steady.
Context Anchor
Seen during instrument turns, especially while maintaining a standard-rate turn by reference to flight instruments.
Derivation
Overbanking' literally means banking beyond what was intended. The 'tendency' part is important — the aircraft is not banking more because the pilot asked it to; it is doing so on its own due to the aerodynamics of the turn.
Why Pilots Care
If left uncorrected the bank can steepen rapidly, raising load factor and increasing the risk of loss of control or spatial disorientation.
Grounding Statement
Picture two wings going around a circle: the outer wing travels a longer path in the same time, so it flies faster, makes more lift, and lifts itself even higher — rolling the aircraft deeper into the turn.
Intuition Check
Do not read this as simply “the pilot banked too much.” Overbanking tendencies are the airplane’s tendency to steepen the bank after the intended bank has already been set.
Example Sentence 1
As the bank passed 30 degrees, the instructor reminded her to apply a touch of opposite aileron to counter the overbanking tendencies.
Example Sentence 2
In the turn the student noticed the bank angle creeping higher and corrected immediately to prevent the overbanking tendencies from becoming a problem.