What instrument reading would you expect to be affected first in a pitot-static problem?

• A. Attitude indicator.
• B. Vertical speed indicator.
• C. Airspeed indicator is typically the first affected because it relies directly on pitot-static pressures.
• D. Compass.

Answer: (C)

The key idea is that the airspeed indicator depends directly on the pitot pressure to determine dynamic pressure. When a pitot-static problem arises, the instrument that uses the pitot pressure is affected first because its input is the stagnation (pitot) pressure itself. If the pitot tube is blocked while the static system remains functioning, the airspeed indicator can read zero or otherwise become unreliable, since it no longer has the pitot pressure to compare against static pressure. The altimeter and vertical speed indicator rely on static pressure, so they will not show the pitot-related fault immediately (assuming the static system is still intact). The attitude indicator and compass aren’t directly fed by the pitot-static pressures, so they aren’t the first to reflect a pitot-static problem.