Which instrument provides near-instantaneous indication of vertical speed?

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

Answer: (C)

The concept here is how quickly a pilot can see changes in vertical speed. The Instantaneous Vertical Speed Indicator is designed to update almost in real time, using a sensor and processing method that minimizes the delay you get with traditional speed indicators. A standard Vertical Speed Indicator relies on a pressure-sensing capsule, which is damped to smooth out fluctuations, so it lags behind actual changes in climb or descent rate. By contrast, the Instantaneous Vertical Speed Indicator provides a much faster indication of how quickly you are gaining or losing altitude, which helps you respond promptly to altitude changes. The airspeed indicator and altimeter measure completely different quantities (speed through the air and altitude, respectively) and do not provide vertical-speed information.