Which instrument uses both pitot and static pressures to provide information?

• A. The airspeed indicator.
• B. The altimeter.
• C. The VSI.
• D. The attitude indicator.

Answer: (A)

Airspeed is determined from dynamic pressure, which is the difference between ram pressure from the pitot tube and the ambient static pressure. The airspeed indicator is a differential pressure instrument that uses both sources: the pitot tube provides the ram (pitot) pressure, while the static ports supply the surrounding ambient pressure. The instrument converts that pressure difference into a display of indicated airspeed. If either source is blocked, the reading can become unreliable, but the fundamental idea remains that dynamic pressure (pitot pressure minus static pressure) drives the indication. The altimeter relies on static pressure alone to show altitude, the VSI uses changes in static pressure over time to indicate rate of climb or descent, and the attitude indicator is gyros-based and not part of the pitot-static system.