Definition
The rate at which an aircraft is climbing or descending, expressed in feet per minute (fpm). A positive value indicates a climb; a negative value indicates a descent. It is shown on the vertical speed indicator (VSI) on the instrument panel.
Plain English
How fast the airplane is going up or down, measured in feet per minute. If the number is positive, you're climbing; if it's negative, you're descending.
Context Anchor
In the developed phase of a spin, the airplane may have a large downward vertical speed, meaning altitude is being lost quickly.
Derivation
“Vertical” comes from a word meaning straight up and down. “Speed” means rate of movement. Together, the term points to movement in the up-and-down direction rather than movement across the ground.
Why Pilots Care
Vertical speed is a key cue during a developed spin: a stabilized, high rate of descent (often 5,000-7,000 fpm or more) is one of the indicators that the spin has fully developed. It also matters in everyday flying for hitting altitude targets, managing descent profiles, and avoiding excessive descent rates near the ground.
Intuition Check
Do not read vertical speed as the airplane’s total speed through the air. It is only the up-or-down part of the airplane’s motion.
Example Sentence 1
During the developed phase of a spin, vertical speed stabilizes at a high downward rate even though the airplane's airspeed remains relatively low.
Example Sentence 2
The pilot monitored the vertical speed indicator closely during spin recovery to confirm the descent rate was decreasing.