Definition
An instrument flight maneuver in which the pilot changes airspeed while simultaneously holding a constant-rate or constant-bank turn. Because changing airspeed alters the airplane's pitch attitude, power requirement, and trim — and because turning already requires back pressure and increased power to maintain altitude — the two changes must be coordinated so that altitude, bank, and turn rate remain constant throughout the speed change.
Plain English
Speeding up or slowing down while you are already in a turn, while keeping your altitude and your turn steady. Several things change at once, so you have to manage power, pitch, and trim together to keep the airplane doing exactly what you want.
Context Anchor
Seen in instrument flying when practicing level turns, standard-rate turns, and scan-and-control corrections using the airspeed indicator.
Why Pilots Care
Uncorrected airspeed changes in turns can produce altitude deviations, increased stall risk, or unstable approach speeds in instrument conditions.
Grounding Statement
Picture rolling into a level turn and holding altitude: the airplane has to work harder, so if you leave the power alone, the airspeed may begin to bleed off.
Intuition Check
Do not assume a turn automatically keeps the same speed. In a level turn, the airplane often needs more lift, and that extra work can reduce airspeed unless the pilot corrects with pitch or power.
Example Sentence 1
ATC told us to slow to 120 knots while turning onto the final approach course, so we practiced change of airspeed during turns until the altitude stayed within ten feet.
Example Sentence 2
During the procedure turn, the pilot monitored airspeed closely to prevent any unwanted change while maintaining altitude.