Which component of the pitot-static system, if blocked, can cause ADS errors?

• A. Pitot tube blockage
• B. GPS signal loss
• C. Static port blockage
• D. Pitot tube blockage or static port blockage

Answer: (D)

The ADS (air data system) relies on accurate pressures from the pitot-static network to calculate airspeed, altitude, and vertical speed. If either the pitot tube or the static port is blocked, those pressure readings become incorrect or unavailable, which prompts the system to detect an ADS fault.

Blocking the pitot tube stops the dynamic pressure input, so indicated airspeed can become unreliable or frozen. Blocking the static port stops the static pressure input, so altitude and vertical speed readings become wrong. Since the ADS uses both sources, either blockage can trigger ADS errors, making it the best answer.

GPS signal loss is not part of the pitot-static system and doesn’t cause ADS errors—it's a navigation data issue rather than air data.