Why do planes get sprayed in winter?

On a snowy morning you may see orange or green fluid sprayed on the aircraft from your window. It's routine preparation before a winter takeoff.

Why is it needed?

A wing's shape is what makes lift. So aircraft are cleaned before takeoff to keep snow, ice or frost off the wings. The rule is simple: wings take off clean.

Two steps

• De-icing: snow and ice are removed with a hot fluid, usually orange.
• Anti-icing: a thicker fluid, usually green, is applied to stop new ice forming before takeoff. It flows off the wing once takeoff speed is reached.

In flight

Aircraft have heating systems on the wing leading edges and engine intakes that prevent icing in flight. Pilots switch them on in icing conditions.

What you notice in the cabin

A faint smell, fluid streaks on the window and a bit of a wait before takeoff. On winter days, the de-icing queue can delay departures by 15–30 minutes. The wait is part of ordinary winter preparation.