Plain English Meaning

An instrument that tells the pilot how fast the aircraft is going up or down, measured in feet per minute.

Full Definition

A flight instrument that displays the rate at which an aircraft is climbing or descending, expressed in feet per minute. It senses the rate of change of static air pressure and shows the result on a needle around a circular dial, with zero in the middle, climb readings above, and descent readings below.

Context Anchor

You see it on the instrument panel during takeoff, climb, descent, and any time you want to confirm whether the airplane is gaining or losing altitude.

Derivation

Vertical means up and down. Speed means rate of motion. Indicator means a device that shows something. So the name describes exactly what it does: it shows how fast you are moving up or down.