Which instruments use static pressure to determine altitude and rate of change in altitude?

• A. Altimeter and VSI
• B. Airspeed indicator and Altimeter
• C. Turn indicator
• D. Attitude indicator

Answer: (A)

Static pressure is what tells you about altitude because pressure decreases as you rise. The instrument that directly shows your altitude uses static pressure from the static port to operate its sealed, expandable element and move the altitude indication on the dial. The vertical speed indicator uses the same static pressure source to sense how quickly that pressure is changing, and it translates that rate of pressure change into a climb or descent rate.

Other instruments aren’t based on static pressure for altitude: the airspeed indicator relies on both pitot (dynamic) pressure and static pressure to derive airspeed, not altitude. The turn and attitude indicators are gyroscopic instruments, not pressure-based in their sensing. So the two instruments using static pressure to determine altitude and its rate of change are the altimeter and the VSI.