Definition
A pitot tube assembly fitted with an internal electric heating element designed to prevent ice from forming in or blocking the tube during flight in visible moisture or at low temperatures. The heater warms the metal of the pitot head so that water droplets and ice crystals do not accumulate and obstruct the ram-air opening or drain holes, which would cause the airspeed indicator to read incorrectly.
Plain English
A pitot tube with a built-in electric heater that keeps it from icing up so the airspeed indicator keeps working in cold or wet conditions.
Context Anchor
Seen in pitot-static system diagrams, blocked-system discussions, preflight checks, and when using the pitot heat switch before or during flight in cold, wet conditions.
Derivation
The word 'pitot' comes from Henri Pitot, the 18th-century French engineer who invented the tube used to measure the speed of moving fluid. 'Head' here means the forward-facing end of the device — the part that catches the oncoming air. Knowing this helps because the pitot 'head' is the exposed sensing tip, and that exposed tip is exactly what needs heating in flight.
Why Pilots Care
Ice blockage produces unreliable airspeed readings that can lead to loss of control in instrument conditions.
Intuition Check
Do not think of the heater as warming the cockpit or heating the air for the engine. Here, the heater warms the pitot probe itself so ice is less likely to block the airspeed pressure opening.
Example Sentence 1
Before entering the clouds, the pilot switched on the pitot heat to keep the pitot head with heater free of ice.
Example Sentence 2
During the preflight inspection the instructor verified that the pitot head with heater was working properly.