Definition
A flat turn is a maneuver in which the airplane changes direction using rudder alone, with the wings held level rather than banked. The rudder yaws the nose around while the ailerons keep the wings parallel to the horizon. In a normal coordinated turn the airplane is banked and the horizontal component of lift pulls it through the turn; in a flat turn there is no bank, so there is no horizontal lift component to turn the airplane efficiently, and the maneuver is uncoordinated and inefficient.
Plain English
Turning the airplane by pushing the rudder pedal while keeping the wings level, instead of banking into the turn the normal way.
Context Anchor
Seen during level-turn training when a student tries to turn with rudder pressure instead of properly banking the airplane.
Derivation
Flat refers to the wings staying level (flat against the horizon) rather than tilting into a bank. The term describes what the airplane looks like from outside during the maneuver.
Why Pilots Care
Flat turns create extra drag, cause altitude loss, and can lead to loss of control, making them unsafe and inefficient for any real maneuvering.
Intuition Check
Do not read “flat” as meaning a good level turn. Here, “flat” means the airplane is not banked enough for the turn and is being pushed sideways with rudder.
Example Sentence 1
The instructor demonstrated a flat turn to show the student how sluggish and uncoordinated the airplane feels without bank.
Example Sentence 2
The handbook warns that flat turns during level flight practice waste energy and make it harder to maintain altitude and coordination.