Definition
A sudden, significant decrease in airspeed or ground speed over a very short period of time. In multiengine flight, the term is used to describe the abrupt loss of forward speed an airplane experiences after the failure of an engine, particularly during takeoff or initial climb, due to the combined effect of lost thrust and increased drag.
Plain English
Slowing down quickly over a short period. The airplane loses speed fast — much faster than it would in a normal power reduction.
Context Anchor
Seen in emergency procedure, landing, braking, and crash-survival discussions, especially when the airplane may stop faster than normal.
Derivation
From Latin 'de-' (away from) and 'celer' (swift), giving 'decelerate' — to move away from swiftness, i.e., to slow down. 'Rapid' simply emphasizes how quickly it happens.
Why Pilots Care
Uncontrolled rapid deceleration during landing or a rejected takeoff can cause loss of directional control, runway excursions, or nose-over tendencies.
Grounding Statement
Picture an airplane rolling normally, then being brought nearly to a stop in only a few seconds.
Intuition Check
Do not read this as normal slowing after landing. Rapid deceleration means the speed drops unusually fast, often fast enough to create strong forward forces on people and objects.
Example Sentence 1
When the right engine failed shortly after liftoff, the airplane experienced a rapid deceleration that required immediate pitch and configuration adjustments.
Example Sentence 2
On a wet runway the crew used aerodynamic braking first to begin rapid deceleration before applying wheel brakes.