Definition
A rate of descent that is greater than normal for the phase of flight, often measured in feet per minute on the vertical speed indicator. On approach and landing, a high sink rate means the airplane is losing altitude faster than the planned descent profile, which can lead to a hard landing, undershoot, or loss of control if not corrected promptly.
Plain English
The airplane is dropping toward the ground faster than it should be. If you don't fix it, you'll either hit the runway hard or come up short.
Context Anchor
Commonly encountered during approaches, landings, go-arounds, and discussions of unstabilized approaches.
Derivation
“Sink” comes from the ordinary idea of moving downward. In aviation, it describes the airplane losing altitude; “rate” means how fast that change is happening.
Why Pilots Care
An uncorrected high sink rate can produce a hard landing that damages landing gear, causes loss of directional control, or results in a runway excursion.
Grounding Statement
On final approach, a high sink rate means the runway is coming up faster than planned and the pilot must correct promptly.
Intuition Check
Do not read “sink” as the airplane falling out of control. Here it means the airplane is descending, but at a rate that may be too fast for the situation.
Example Sentence 1
On short final, the pilot noticed a high sink rate and added power to arrest the descent before touchdown.
Example Sentence 2
The instructor emphasized that any high sink rate below fifty feet demands an immediate go-around.