Definition
A small, refining control input made along a curved path of the control wheel or stick after the initial (primary) input has established the desired attitude. The secondary motion fine-tunes bank, pitch, or coordination — for example, easing pressure off after the bank is set, or making minor corrections to hold the attitude through the maneuver.
Plain English
After your first control movement sets up the turn, you make a smaller follow-up movement to adjust and hold the airplane where you want it. It is the gentle second input that polishes what the first input started.
Context Anchor
Seen in explanations of how elevator back pressure works while establishing and holding a turn.
Derivation
Secondary means 'second in order.' Arc refers to the curved path the control wheel or stick travels through. Together it describes the second, follow-up movement along that curved path — the refining input that comes after the primary one.
Why Pilots Care
Prevents uncoordinated flight that wastes energy, reduces control effectiveness, and can lead to loss of directional control or stall during turns.
Grounding Statement
Picture the airplane tilted left in a turn: when you pull back, some of the added lifting force points sideways into the turn instead of straight upward.
Intuition Check
Secondary does not mean unimportant; it means it is not the control’s main action. Arc does not mean a chart arc here; it means the curved path the airplane follows in the turn.
Example Sentence 1
After rolling into the 30-degree bank, she applied a small secondary arc control motion to relax the aileron pressure and hold the bank steady.
Example Sentence 2
A smooth secondary arc control motion during roll-out helps the airplane return to wings-level flight without yaw.