What effect does icing have on pitot-static instruments?

• A. Ice can block the pitot and static ports, causing unreliable readings or failures
• B. Ice reduces readings
• C. There is no effect
• D. It only affects the pitot tube, not static ports

Answer: (A)

Ice blocking the pitot-static system means the airplane loses the pressure signals that feed the instruments. The pitot tube provides dynamic pressure to determine airspeed, while the static ports supply ambient pressure for the altimeter and vertical speed indicator. If ice blocks these openings, the pressures can’t be read correctly, so the airspeed indicator can give unreliable or completely misleading readings, and the altimeter and VSI may stop updating or show incorrect changes. Since icing can affect both the pitot tube and the static ports, this leads to overall unreliable performance of the pitot-static instruments, which is why this choice is the best.