Which instrument requires both Pitot and static pressure?

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

Answer: (A)

Airspeed is determined from dynamic pressure, which comes from the difference between the Pitot (total) pressure and the ambient static pressure. The airspeed indicator is connected to both sources: Pitot provides total pressure on one side, static pressure is supplied to the other. The instrument’s mechanism responds to the pressure difference and the scale is calibrated to display indicated airspeed. In short, the speed you read depends on how much the air presses on the aircraft relative to the surrounding air, which requires both pressures.

Altimeter uses static pressure to determine altitude, and the vertical speed indicator relies on the rate of change of static pressure to show climb or descent, while the attitude indicator is gyroscopic and does not depend on Pitot-static pressures. If one source is blocked, readings can become unreliable, underscoring why the airspeed indicator needs both inputs.