What instrument indicates the aircraft's vertical speed?

The Vertical Speed Indicator (VSI) is specifically designed to show the rate of climb or descent of the aircraft. It provides this information in feet per minute, indicating whether the aircraft is gaining altitude or descending. The VSI measures changes in air pressure, reacting to the vertical movement of the aircraft. When an aircraft climbs or descends, the pressure changes at the static port, which the VSI interprets to give the pilot crucial information about their vertical performance in real-time.

The other instruments serve different purposes: the altimeter measures the aircraft's altitude, the airspeed indicator measures the speed of the aircraft relative to the surrounding air, and the attitude indicator shows the orientation of the aircraft concerning the horizon. Each of these instruments plays a vital role in flight but does not indicate vertical speed, thereby reinforcing the uniqueness and importance of the VSI in providing vertical velocity information.