What does the pitot-static system supply to the instruments?

• A. Pitot pressure to the airspeed indicator; static pressure to the altimeter and vertical speed indicator.
• B. Static pressure to the airspeed indicator; pitot pressure to the altimeter.
• C. Pitot pressure to the altimeter; static to the airspeed indicator.
• D. Dynamic pressure to the airspeed indicator; static pressure to the VSI.

Answer: (A)

Pitot-static signals come from two sources: pitot pressure and static pressure. The airspeed indicator uses the pitot pressure as the ram air (total) pressure and references it to ambient static pressure to sense dynamic pressure, which is what relates to how fast the aircraft is moving through the air. The altimeter and vertical speed indicator rely on static pressure alone: the altimeter converts ambient static pressure into an altitude, while the VSI responds to changes in static pressure to show rate of climb or descent. So the pitot-static system supplies pitot pressure to the airspeed indicator and static pressure to the altimeter and VSI.