Definition
A cockpit switch that turns on an electrical heating element inside the pitot tube to prevent or remove ice blockage of the ram-air inlet, ensuring the airspeed indicator continues to receive accurate impact pressure in visible moisture or freezing conditions.
Plain English
A switch in the cockpit that turns on a small heater inside the pitot tube so it does not freeze over and stop the airspeed indicator from working.
Context Anchor
Seen on cockpit switch panels and in pitot-static system diagrams, especially when discussing airspeed indications and icing conditions.
Derivation
Pitot is named after Henri Pitot, the 18th-century French engineer who developed the tube used to measure fluid speed. Knowing the tube is a small forward-facing air inlet helps explain why it needs heat: any ice forming over the opening blocks the airflow that drives the airspeed indicator.
Why Pilots Care
Ice in the pitot tube produces false or zero airspeed indications, which can lead to loss of control in instrument conditions.
Grounding Statement
In cold, wet air, the pitot heater switch powers heat at the outside tube so ice is less likely to seal the opening.
Intuition Check
Do not assume this switch heats the cockpit instrument or the static port. It normally controls heat for the pitot tube itself.
Example Sentence 1
Before entering the clouds, she turned the pitot heater switch on to prevent ice from blocking the tube.
Example Sentence 2
During the preflight inspection the pilot verified that the pitot heater switch was operational and that the tube was warm to the touch.