Definition
A pair of ailerons mounted on the inboard section of each wing, closer to the fuselage, used for roll control during high-speed flight. On large jet transports, these are the only ailerons active at high speeds, while the outboard ailerons are locked out to prevent excessive wing twist and loss of roll authority.
Plain English
On a big jet, the roll-control surfaces nearer the body of the wing take over for the ones near the wingtip when the airplane is flying fast. They give the pilot a smaller, safer amount of roll movement at high speed.
Context Anchor
Seen in discussions of high-speed flight controls, especially on larger or faster airplanes that may limit or lock out outboard aileron use at higher speeds.
Derivation
Inboard simply means 'closer to the centerline' (the opposite of outboard, meaning toward the wingtip). The name describes their location and the speed regime in which they remain active.
Why Pilots Care
Using the inboard surfaces prevents excessive wing twist and maintains precise roll response at speeds where outboard ailerons become ineffective or structurally risky.
Grounding Statement
At higher speeds, the air loads on the outer wing are stronger, so moving roll control inward helps the wing respond without being twisted as much.
Intuition Check
“High-speed” does not mean the ailerons themselves move faster. It means these inboard ailerons are intended for use when the airplane is flying at higher speeds.
Example Sentence 1
Once the jet accelerated past the changeover speed, only the high-speed inboard ailerons remained active for roll control.
Example Sentence 2
During the descent the pilot verified that the high-speed inboard ailerons were armed before accelerating past 300 knots.