Definition
The deliberate use of rudder and aileron in opposing or unmatched amounts so that the airplane is no longer flying in coordinated flight. In a slip, for example, the pilot banks the wings in one direction with aileron while applying rudder in the opposite direction, causing the airplane to fly partially sideways through the air rather than straight along its longitudinal axis.
Plain English
The pilot is intentionally pushing the rudder pedal one way and rolling the wings the other way, so the airplane flies a little sideways instead of straight ahead. This is the control input that creates a slip.
Context Anchor
Seen in discussions of intentional slips, crosswind landings, and coordinated flight control use.
Derivation
Coordinate comes from Latin roots meaning “arranged together.” In aviation, coordinated control means the rudder and ailerons are working together for the desired flight path. Aileron comes from French for “little wing,” which fits because ailerons are small movable parts on the wings.
Why Pilots Care
Uncoordinated inputs during a slip can cause one wing to stall first or allow the airplane to drift off the intended ground track.
Grounding Statement
Picture the airplane banked one way while the nose is being held another way; that sideways mismatch is the key idea.
Intuition Check
Uncoordinated does not mean the pilot is simply being sloppy. Here it means the rudder and ailerons are not balanced in the normal coordinated way, either intentionally for a slip or unintentionally by mistake.
Example Sentence 1
On short final with a strong crosswind, the pilot used uncoordinated rudder/aileron application to keep the nose aligned with the runway centerline while the upwind wing stayed lowered into the wind.
Example Sentence 2
During the crosswind landing practice, uncoordinated rudder/aileron application caused the airplane to weathervane and drift downwind of the runway centerline.