Now that winter is upon us, the potential for aircraft icing is something that all pilots need to be aware of.  Aircraft icing destroys the smooth flow of air, increasing drag while decreasing the ability of the airfoil to create lift.   

The actual weight of the ice on the airplane is insignificant when compared to the airflow disruption it causes.  As power is added to compensate for the additional drag and the nose is lifted to maintain altitude, the angle of attack is increased, allowing the underside of the wings and fuselage to accumulate additional ice.  Ice accumulates on every exposed frontal surface of the airplane-not just on the wings, propeller, and windshield, but also on the antennas, vents, intakes, and cowlings.  It builds in flight where no heat or boots can reach it.  Ice can cause antennas to vibrate so severely that they break.  In moderate to severe conditions, a light aircraft can become so iced up that continued flight is impossible. The airplane may stall at much higher speeds and lower angles of attack than normal.  It can roll or pitch uncontrollably, and recovering may be impossible.  Ice can also cause engine stoppage by either icing up the carburetor or, in the case of a fuel-injected engine, blocking the engine’s air source.

Wind tunnel and flight tests have shown that frost, snow, and ice accumulations on the leading edge or upper surface of the wing no thicker or rougher than a piece of course sandpaper can reduce lift by 30 percent and increase drag up to 40 percent.  Larger accretions can reduce lift even more and can increase drag by 80 percent or more.