Definition
A pitot-static flight instrument that displays the rate at which the aircraft is climbing or descending, expressed in feet per minute (fpm). It senses the rate of change of static pressure as altitude changes and shows that rate on a needle against a calibrated scale, with zero in the level-flight position, climb above, and descent below.
Plain English
A cockpit gauge that shows how fast you are going up or coming down, measured in feet per minute. The needle points to zero in level flight, above zero when climbing, and below zero when descending.
Context Anchor
Seen on the instrument panel during climbs, descents, level-off, and instrument flying.
Derivation
Vertical means up-and-down motion. Speed indicator means a gauge that shows rate. Together: a gauge that shows the rate of vertical motion. The name describes exactly what the instrument does.
Why Pilots Care
Helps maintain exact climb or descent rates required by ATC, performance charts, or terrain clearance.
Intuition Check
Do not read “vertical speed” as the airplane’s total speed. It means only the rate of movement upward or downward, usually shown in feet per minute.
Example Sentence 1
After takeoff the pilot adjusted pitch until the VSI showed a steady 700 fpm climb.
Example Sentence 2
During the descent the vertical speed indicator showed 800 feet per minute, so power was reduced to stay on profile.