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.
Plain English
The instrument that shows how fast the aircraft is moving through the air stops giving a correct reading, or any reading at all.
Context Anchor
Seen in abnormal and emergency procedures, including an inadvertent thunderstorm encounter, where heavy rain, ice, or equipment problems may make the airspeed reading unreliable.
Derivation
Indication comes from a word meaning “to point out” or “to show.” In this term, the important idea is that the airplane has not necessarily lost airspeed; it has lost the instrument’s ability to show airspeed reliably.
Why Pilots Care
Accurate speed information is essential for maintaining safe flight; without it, the risk of stall or loss of control increases sharply in turbulent conditions.
Grounding Statement
The airplane may still be moving safely through the air even when the cockpit speed reading can no longer be trusted.
Intuition Check
Do not read this as “the airplane lost its airspeed.” It means the pilot lost a reliable airspeed reading.
Example Sentence 1
After entering heavy rain, the crew experienced a loss of airspeed indication and immediately set the briefed pitch attitude and power for level flight.
Example Sentence 2
In heavy rain, loss of airspeed indication can occur quickly, requiring immediate use of backup references.