Definition
To reduce speed; in aviation, the act of slowing the aircraft's velocity, whether in flight or on the ground, through reduced thrust, increased drag, braking, or a combination of these.
Plain English
To slow down. The aircraft is going more slowly than it was a moment ago.
Context Anchor
Seen in thrust and air resistance discussions, airspeed control, landing, and stopping after touchdown.
Derivation
From Latin de- (down, away from) and celer (swift, fast). Literally 'to take away swiftness.' The opposite of accelerate.
Why Pilots Care
Proper deceleration technique prevents excessive airspeed on approach and ensures safe speed management throughout all phases of flight.
Intuition Check
Decelerate does not only mean using wheel brakes. An airplane can decelerate by reducing thrust, increasing air resistance, climbing, or braking after landing.
Example Sentence 1
After touchdown, the pilot used wheel brakes and reverse thrust to decelerate before reaching the end of the runway.
Example Sentence 2
After touchdown the airplane continued to decelerate as reverse thrust was applied.