What occurs when the Pitot Tube becomes blocked?

When the Pitot Tube becomes blocked, it leads to a malfunction that causes the airspeed indicator to behave incorrectly. Specifically, a blockage typically results in the reading indicating an altitude rather than true airspeed. This happens because the Pitot Tube measures dynamic pressure—essentially, the difference between static pressure and the impact pressure of the air as the helicopter moves forward. If it is blocked, it cannot accurately sense this dynamic pressure, and as the helicopter climbs or descends, the airspeed indicator can respond to changes in atmospheric pressure, mimicking the behavior of an altimeter.

In this situation, readings may be misleading, presenting the pilot with the appearance of altitude changes rather than actual airspeed, even though the aircraft's speed through the air has not changed. Understanding this behavior is crucial for helicopter pilots, as reliance on incorrect airspeed readings can pose serious risks during flight operations.