What is the primary function of the vertical speed indicator?

The primary function of the vertical speed indicator (VSI) is to indicate the climb or descent rate of the aircraft. This instrument provides critical information to pilots by displaying how many feet per minute the aircraft is rising or falling. Understanding the rate of climb or descent is essential for various phases of flight, including takeoff, approach, and landing, as it helps pilots maintain the desired altitude and ensures safe vertical navigation.

This information is particularly important during takeoff and landing, as pilots need to make precise adjustments to their flight path. The VSI contributes to situational awareness, enabling pilots to assess how effectively they are following their climb or descent profile, facilitating smoother transitions between altitudes and helping to prevent loss of control due to excessive rates of climb or descent.