Definition
An electrical heating element built into the pitot tube that prevents ice from forming in or over the tube's opening during flight in visible moisture or freezing conditions. When activated, it warms the pitot tube so that the ram air inlet stays clear and continues to deliver accurate pressure information to the airspeed indicator.
Plain English
A small built-in heater that keeps the airspeed sensor on the outside of the aircraft from icing up. The pilot turns it on with a switch so the airspeed reading stays reliable in cold or wet conditions.
Context Anchor
Seen during preflight and before-engine-start checks, especially before instrument flight or flight in cold, wet conditions.
Derivation
Pitot comes from Henri Pitot, the 18th-century French engineer who designed the tube used to measure fluid speed. The 'heater' part is exactly what it sounds like — an electrical element that warms the tube so it doesn't freeze.
Why Pilots Care
Ice blockage produces false or zero airspeed indications that can lead to loss of control in instrument conditions.
Grounding Statement
The pitot tube heater protects a small air opening that the airplane depends on for a usable airspeed indication.
Intuition Check
Do not think of this as a comfort heater or a general ice-removal system. It only heats the pitot tube area so the airspeed system can keep receiving pressure from outside air.
Example Sentence 1
During the before-engine-start check, the pilot briefly turned on the pitot tube heater and confirmed it was warming up before switching it back off.
Example Sentence 2
During the instrument cockpit check the pilot confirmed the pitot tube heater was drawing current before takeoff into possible icing.