What is the function of the vertical speed indicator?

• A. To show the aircraft's orientation in relation to the horizon
• B. To indicate the current heading of the aircraft
• C. To show the rate of climb or descent in feet per minute
• D. To provide engine speed information

Answer: (C)

The vertical speed indicator (VSI) serves a critical function in monitoring the aircraft's performance by displaying the rate of climb or descent, measured in feet per minute. This instrument is essential for pilots to understand their vertical position relative to the ground, allowing them to make informed decisions during ascent or descent phases of flight.

When the aircraft is climbing, the VSI will show a positive rate, while during descent, it will indicate a negative rate. This information is vital for maintaining safe altitude changes and for ensuring that approaches and landings are executed smoothly. By providing a clear visual representation of the vertical speed, the VSI helps pilots maintain optimal flight path angles and adherence to altitude restrictions during various phases of flight.

The other options do not represent the primary function of the VSI. For instance, orientation in relation to the horizon is indicated by the artificial horizon or attitude indicator, heading information is shown by the heading indicator, and engine speed is typically monitored through an engine tachometer or RPM gauge. Each of these instruments serves specific roles that complement the information provided by the vertical speed indicator.