Static system dump results in failure of how many instruments?

• A. One
• B. Two
• C. None
• D. All three

Answer: (D)

Ambient static pressure is the reference for the three pitot-static instruments. The altimeter relies on static pressure to display altitude, the vertical speed indicator uses the change in static pressure to show climb or descent, and the airspeed indicator depends on the difference between pitot (dynamic) pressure and static pressure. If the static system is dumped, that reference is lost, causing all three instruments to lose or misrepresent their readings. So, the failure affects every instrument that uses static pressure—the three primary pitot-static instruments.