Final answer:
When a pitot tube is blocked, the ASI will indicate a constant airspeed.
Step-by-step explanation:
A sudden blockage of a pitot tube will cause the ASI (Airspeed Indicator) to behave in a particular way. The pitot tube is responsible for measuring the dynamic pressure of the airflow, which is used to calculate airspeed. When the pitot tube is blocked, there will be no airflow into the tube, resulting in a zero dynamic pressure. As a result, the ASI will indicate a constant airspeed, which is typically the last value shown before the blockage occurred.