Plain English Meaning
The instrument that shows how fast the aircraft is moving through the air stops giving a correct reading, or any reading at all.
Full Definition
A condition in which the airspeed indicator fails to display accurate or any airspeed information, typically caused by blockage or damage to the pitot-static system from icing, water, debris, insects, or a covered pitot tube. In thunderstorm encounters, heavy precipitation, hail, or rapid pitot heat failure can produce sudden airspeed errors or a complete loss of indication.
Context Anchor
Seen in , including an , where heavy , , or equipment problems may make the airspeed reading .