Planes are also affected by sub-zero temperatures, snow and frost. But thanks to the de-icing equipment airports, they can still operate their scheduled flights. Iberia's de-icing equipment consists of a fleet of trucks fitted with a 5,000-litre tank of water mixed with glycol, and a boiler that heats the mixture to 2 degrees Celsius for spraying onto the plane. The truck's pumps make the water rise so that when the operator opens the nozzle, the liquid spurts out with the necessary force to fall onto the plane. The water melts the ice, frost or snow, while the glycol prevents it from forming again for a given period of time. The de-icing procedure is usually carried out for the vertical and horizontal planes (wings and tail), as well as the fuselage, radome, landing gear doors and stabilisers. In extreme weather conditions and if requested by the captain, the entire plane is de-iced. This procedure is executed in strict accordance with the instructions in the aircraft manufacturer's manuals and IATA regulations. It can take 3 to 5 minutes the clear ice and frost from a plane, and up to 1 hour to clear snow. Madrid-Barajas has two de-icing bases operating 24/7, and in normal circumstances three planes can be cleared simultaneously at each base.