Which instrument is used to measure the rate of climb or descent?

• A. Airspeed Indicator
• B. Altimeter
• C. Vertical Speed Indicator
• D. Attitude Indicator

Answer: (C)

The rate of climb or descent is shown by the instrument that measures how fast you’re moving vertically, usually expressed in feet per minute. It does this by monitoring changes in the outside air pressure from the static port and using a calibrated leak to sense how quickly that pressure is changing as you climb or descend. When you start climbing, the ambient static pressure drops, and the instrument responds by deflecting to indicate a positive rate. When you descend, the opposite happens and it shows a negative rate. If you’re level, the needle sits near zero. There is some delay because the mechanism is vented to smooth the reading, so rapid changes won’t be shown instantaneously. This instrument is different from the airspeed indicator, which measures dynamic pressure to show speed; from the altimeter, which shows altitude based on static pressure; and from the attitude indicator, which shows the aircraft’s orientation relative to the horizon.