Learn what pitot heat does, when to switch it on, how icing affects airspeed indications, and the key real-world and simulator safety checks.
Pitot heat is an electrical heater built into the pitot probe that prevents ice from blocking the pressure inlet and corrupting indicated airspeed. In real-world aviation and flight simulation, use it as the aircraft checklist directs—normally before entering visible moisture in icing temperatures; many jets regulate it automatically or use it throughout flight.
How does pitot heat work?
The pitot probe measures total pressure from the airflow, while the static system measures ambient pressure. Their difference lets the airspeed indicator or air-data computer calculate indicated airspeed; our explanation of how indicated airspeed relates to Mach covers that relationship in more detail.
An electrical element warms the probe body and its openings so that supercooled water cannot freeze across them. Pitot heat is primarily anti-icing protection: it is better at preventing a blockage than recovering from one after substantial ice has formed.
Equipment varies by aircraft. A simple light-aircraft switch may heat only the pitot tube, while an airliner's probe-heating system may also protect static probes, angle-of-attack sensors and temperature probes. Pitot heat does not automatically protect every part of the pitot-static system.
When should you turn pitot heat on?
Turn pitot heat on at the point specified by the aircraft's POH, AFM, checklist or operating procedure, and always before entering conditions in which the probe could ice.
- Follow the aircraft checklist: some light aircraft call for pitot heat only when icing is suspected, while other aircraft require probe heat before take-off or throughout flight.
- Act before visible moisture: use it before entering cloud, fog, rain, drizzle, sleet or snow when the temperature permits icing. Waiting for the airspeed indication to fail is too late.
- Do not apply a universal temperature: many turbine-aircraft procedures use a temperature such as 10°C or colder as part of their icing definition, but thresholds and exceptions differ. Use the definition published for that aircraft.
- Check the system before flight: perform only the test specified by the checklist. Confirm that any pitot cover has been removed before energising the heater.
Weather reports help with planning, but they cannot prove that the next cloud is ice-free. Learn to identify temperature, cloud and freezing-precipitation clues in a METAR, then apply the aircraft's operating rules rather than relying on the report alone.
Can pitot heat be left on continuously?
Pitot heat may be left on continuously only when the aircraft's system and checklist are designed for that use. Many transport aircraft regulate probe temperature automatically or provide reduced heating on the ground and full heating in flight.
On other aircraft, unnecessary ground operation creates electrical load and can make the probe hot enough to cause a serious burn. Never touch an energised probe, and do not assume every installation tolerates prolonged ground heating.
What happens if the pitot tube freezes?
A blocked pitot source can make indicated airspeed fall towards zero, stop responding to speed changes or vary with altitude instead of airspeed.
| Problem | Likely instrument behaviour | Will pitot heat help? |
|---|---|---|
| Pitot inlet blocked but drain remains open | Pitot pressure bleeds away and indicated airspeed normally falls towards zero. | Usually, if ice caused the blockage and the heater still works. |
| Pitot inlet and drain both sealed | Pressure becomes trapped. At a constant altitude the indication may stop responding normally; during climbs and descents it can behave roughly like an altimeter. | Possibly, but clearing the ice may take time. |
| Static source blocked | Airspeed, altitude and vertical-speed information can all become misleading. | Not unless that static source has its own heating system. |
In a real aircraft, unreliable airspeed demands the published unreliable-airspeed procedure: establish known pitch and power, compare independent instruments and follow the POH or QRH. Switching on pitot heat is sensible if the procedure calls for it, but it is not a substitute for controlling the aircraft. GPS groundspeed is not equivalent to airspeed because wind can create a large difference between them.
Can pitot heat clear an already frozen tube?
Working pitot heat may thaw a frozen probe, but recovery is not guaranteed or immediate. The outcome depends on the amount of ice, heater output, airflow and whether the blockage is actually ice rather than insects, debris, a forgotten cover, wiring failure or an air-data fault.
Does pitot heat prevent aircraft icing?
Pitot heat protects sensing equipment, not the wings, propeller, windscreen, engine inlets or tail. It does not make flight through severe icing safe and must not be treated as general aircraft de-icing equipment.
Other systems may use heated leading edges, pneumatic boots or fluid, each with its own limitations. Our guide to recognising and avoiding aircraft icing explains the wider risk and why leaving the conditions remains the safest response when protection is inadequate.
How should you use pitot heat in a flight simulator?
In a flight simulator, operate pitot heat according to the simulated aircraft's checklist rather than using one rule for every aeroplane.
- Find the correct control: it may be labelled
PITOT HEAT,PROBE HEATor grouped with anti-ice controls. - Switch it on at the prescribed phase: this may be during the before-take-off checks, after engine start or before entering icing conditions.
- Recognise a simulated blockage: if airspeed freezes or becomes implausible, hold a known pitch-and-power setting, compare standby indications and check the heat switch without chasing the faulty instrument.
- Allow for modelling differences: detailed aircraft may simulate separate probes, electrical buses, heating delays and air-data warnings. Simpler models may clear the failure immediately or model no pitot icing at all.
A common simulator mistake is turning pitot heat on only after the airspeed indicator has failed. Another is assuming that no visible ice means no pitot icing; the simulator may model a probe blockage without drawing ice on the aircraft.