What is the primary function of the Vertical Speed Indicator?

The primary function of the Vertical Speed Indicator (VSI) is to show climb and descent rates. This instrument is essential for pilots as it provides real-time feedback on how quickly the aircraft is ascending or descending, measured in feet per minute (fpm). This information helps pilots maintain a desired flight path and makes it easier to manage the aircraft’s altitude during climbs and descents.

By understanding the VSI's readings, pilots can make informed decisions about adjustments needed for maintaining altitude or optimizing their climb or descent rates, enhancing safety and operational efficiency during various phases of flight.