What does the vertical speed indicator (VSI) display?

The vertical speed indicator (VSI) is an essential instrument in the cockpit that provides critical information regarding the aircraft’s vertical movement. Specifically, it displays the rate of ascent or descent in feet per minute. This functionality allows pilots to monitor how quickly they are gaining or losing altitude, which is crucial for maintaining control during climbs and descents.

When the aircraft is climbing, the VSI will show a positive reading, indicating how many feet the aircraft is ascending each minute. Conversely, during descent, the VSI will indicate a negative reading, reflecting the rate at which altitude is being lost. This instrument can help pilots make informed decisions regarding altitude adjustments, ensuring safety during flight operations.

Understanding the specific function of the VSI is important, as it differentiates from other instruments that measure airspeed, altitude, or heading. The airspeed indicator measures how fast the aircraft is moving through the air, the altimeter indicates the current altitude of the aircraft, and the heading indicator shows the direction in which the aircraft is flying. Each of these instruments serves a distinct purpose, but the VSI's unique role is specifically to quantify vertical speed.