Definition
A ground test performed during the takeoff roll of certain aircraft (typically high-performance or transport-category) to confirm that the aircraft is accelerating at the rate predicted by performance charts. If the aircraft has not reached a target groundspeed by a specified point on the runway, the takeoff is rejected.
Plain English
A check during the takeoff run that compares how fast the aircraft is actually speeding up against how fast it should be. If it isn't speeding up quickly enough by a set point on the runway, the pilot stops the takeoff.
Context Anchor
Seen during turbine engine run-ups, maintenance checks, and engine performance checks.
Derivation
Acceleration comes from the Latin accelerare, meaning “to hasten” or “to speed up.” That helps here because the check is about how quickly the engine speeds up, not how quickly the airplane moves.
Why Pilots Care
Confirms that engine and aircraft performance meet expectations; failure to accelerate properly signals the need to abort the takeoff to avoid insufficient runway or climb capability.
Intuition Check
Do not read this as a check of the airplane’s acceleration down the runway. In this context, it means checking how quickly the engine itself accelerates from idle to the required power setting.
Example Sentence 1
The first officer called out the acceleration check at the runway midpoint, confirming they had reached the expected groundspeed.
Example Sentence 2
If the acceleration check shows slower than expected speed gain, the pilot immediately aborts the takeoff.