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Icing Conditions Pilots should be aware that Ice does not only form at 0 Celsius or 32 degrees Fahrenheit and below. it can be up to 25 Centigrade Ice can cause a loss of engine power, a change in the centre of gravity which can cause control difficulties. Vibration in propellers. Blockage of pitot head and static vents and engine instruments probes this can give false readings.. If formed on radio antennas can hinder radio communication or use of radio navigation equipment. It also can destroy lift over wings. Ice can be in various forms
Super Cooled Water Drops Liquid water drops can exist in the atmosphere well below 0 degrees Centigrade These top of drops will freeze on impact with an aircraft or propeller which may have a very cold surface. Cumulus and Stratus type clouds can well have this type of ice in. (especially if the temperature id between 0C and -20 C) Raindrops and Drizzle If the aircraft has a cold surface rain and drizzle may freeze on impact This can happen when a temperature inversion occurs. Carburetor Icing This can form in temperatures up to 25 Centigrade. Heat switches are on these types of aircraft the pilot should operate this for a couple of seconds. A sign of this is the engine running rough and a loss of revs. In a long descent the pilot should leave the switch out and just rev the engine for a few seconds every 500 ft. Icing can happen in clear air as well. Operating the carburetor heat switch can cause the engine to splutter for up to 15 seconds. In the cruise it is suggested that pilot pull out the carb heat switch about every ten minutes for 5 seconds. Pilots should do this around the circuit and on finals push the switch in about 200 ft from landing in case full power is required for a go around.
Pre Flight Checks Fuel tanks can get condensation water in them. Underneath is a drain valve for a test tube. Pilots should ensure before flight that the water is drained from the fuel. All surfaces must be clear of ice before flying or starting engines. Altimeters over read in low temperatures. Wet snow or slush can increase the take off run. Taxi slowly especially in turns on taxiways. Pilots normally turn icing systems in below 10 degrees Centigrade temperature. Landing Even a thin layer of ice on an aircraft a pilot for safety should increase the landing speed by 20%. Watch out for wet runways becoming frozen runways late afternoon. Emergencies If you are in trouble tell Air Traffic Control who will help you and warn others. It is possible for the aircraft to land without flaps but this will be faster and a flatter approach angle. it may mean ice on the tail plane causing the aircraft to pitch down putting flaps out will only make things worse. If your aircraft is getting covered in ice you may have to turn back climb or descend into warmer air or make an emergency forced landing. The main thing is make your decision early do not wait until your aircraft is smothered in ice first. Holding Point for Take Off Remember there is no such thing as a little bit of ice it will be alright. Get the aircraft full deiced before flight. if stood to long at the holding point it may need to be done again. Do not get to close to an aircraft in front as when it moves off it may well blow snow sleet and ice all over your aircraft.. When it is your turn to rake off taxi onto the runway slowly and try not to blow snow over other aircraft behind you. Ensure the carburetor heat switch is in for take off. If not it will cause loss of power. |