Soar to New Heights with the 2025 Commercial Pilot License (CPL) Practice Exam – Ready for Takeoff!

When the pitot tube becomes blocked, the airspeed indicator will show a reading of zero airspeed. This is because the pitot tube is responsible for measuring dynamic pressure, which is crucial for calculating the indicated airspeed. If the pitot tube is obstructed, it cannot sense the air pressure changes that indicate how fast the aircraft is moving through the air. Consequently, the airspeed indicator will freeze at zero or, in some cases, show a very low reading, representing no airspeed input from the blocked pitot system.

It's important to note that if other flight instruments, such as the static ports, were to remain clear, the altimeter and vertical speed indicator could continue to function correctly. However, the airspeed indicator's reliance solely on the pitot tube function means that a blockage will directly lead to a reading of zero. This operational understanding is vital for pilots, as a blocked pitot tube represents a critical failure in airspeed monitoring that requires immediate corrective action.