De-icing: Why It Happens and What It Means
2 min read
The short answer
Planes must take off completely free of ice, frost and snow. Before winter departures, they're sprayed with special fluid that removes ice and stops it coming back. In the air, heated wings and engines keep ice away.
Ice and Planes: A Managed Risk
Ice on the wings is a real hazard — but one that aviation manages with thorough, reliable systems. If you've seen a plane sprayed with orange or green fluid before a winter departure, you've seen one of them at work.
Why Ice Matters
Ice disrupts the smooth airflow over the wings that creates lift. Even frost as thin as coarse sandpaper can cut lift by up to 30%. It can also raise drag by up to 40%.
That's why aviation follows a strict "clean aircraft" rule. No plane may take off with frost, ice or snow on its wings, tail or control surfaces.
De-icing on the Ground
Before winter departures, planes are sprayed with special de-icing fluid. There are two main types:
- The first spray (orange) is hot fluid, sprayed at high pressure. It removes ice and snow, but only protects for a short time.
- The second spray (often green) is thicker and applied cold. It clings to the plane and stops new ice forming while it taxis. It protects for longer.
The crew works out how long the protection will last, based on the fluid, the temperature and the weather. If the plane hasn't taken off in time, it goes back to be sprayed again. There's no guesswork.
Ice Protection in the Air
Once airborne, the plane's own systems take over. Hot air from the engines heats the front edges of the wings and the engine intakes, so ice can't build up.
The sensors that measure speed and height are heated electrically too, so they stay ice-free.
Ice Detection
Modern planes have ice detectors that alert the crew when icing conditions are present. Pilots can also switch on ice protection early when flying through cloud or rain near freezing.
The Result
Ground de-icing, heated wings and ice detectors give planes several independent layers of protection. Ice problems on airliners are extremely rare precisely because of these systems.
Sources
- FAA, Aircraft Icing: https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap7_section_1.html
- CNN, The science behind airplane deicing (2025): https://www.cnn.com/travel/airplane-deicing-science-explainer-scn/index.html
- AOPA, Deicing and Anti-Icing Equipment: https://www.aopa.org/training-and-safety/online-learning/safety-spotlights/weather-wise-precipitation-and-icing/deicing-and-anti-icing-equipment