Time to Review Aircraft Icing

Winter offers pilots a unique beauty from up above, as well as seasonal dangers due to cold and icing. Whether or not you fly in cold weather, it’s important for pilots and FBOs to understand the basics of icing and know how to prevent and reduce the risk of ground and airborne icing. Here are some things to know and do.

Keep in mind this is a general overview on aircraft icing. Be sure to refer to the Original Equipment Manufacturer Aircraft (OEM) de-icing recommendations and your FBO/aircraft mechanic for the necessary pre-flight preparation for your aircraft.

Understanding the effects of icing

Airborne icing is dangerous for multiple reasons: It distorts the smooth flow of air over the wings, reducing the wing’s maximum lift, adversely affects the plane’s handling qualities, and significantly increases drag.

When icing occurs, it can build up on every exposed frontal surface of the plane, including the wings, propeller, windshield, antennas, vents, intakes, and cowlings. But the weight of ice on the airplane is actually a secondary problem to the airflow disruption the ice buildup causes. As a pilot adds power to make up for increased drag, the nose lifts to maintain altitude, allowing the underside of the wings and fuselage to accumulate even more ice, causing yet more lift, handling, and drag problems.

In moderate to severe conditions, an aircraft can become so iced up that continued flight is impossible. The plane may stall at higher speeds and lower angles of attack than normal, or roll or pitch uncontrollably. Ice can also cause engine stoppage by icing up the carburetor or blocking the engine's air source.

Don’t underestimate the hazards associated with frost formations, particularly at low airspeeds, takeoffs and landings. If left on an aircraft, frost can increase drag, prevent windshield visibility and even cause fatal engine failure.

When temperatures drop below two degrees Celsius (35.6 degrees Fahrenheit), ice, frost or frozen slush can form on an aircraft’s wings both on the ground and in the air. Frozen contaminants about the size of medium to coarse sandpaper can reduce maximum wing lift by 30 percent, or increase lift-induced drag by 40 percent. The results of not taking frozen contaminates seriously can be devastating.

Planning ahead is key

The key to minimizing icing risks before or during flight is proper planning and preparation. If you fly in cold weather, do your due diligence to plan ahead, check weather, and avoid locations where icing is likely.

If possible, hangar your aircraft indoors during the winter to protect it from frost and frozen precipitation. Before flying, know the weather at your FBO, en-route and destination airports. If airborne icing is likely, postpone the trip if possible, or make alternate route and airport plans to work around the weather.

If you have to fly, contact the FBO about their de-icing and anti-icing capabilities, as well as your aircraft’s requirements. Review your aircraft’s Original Equipment Manufacturer Aircraft (OEM) de-icing recommendations.

On winterization kits

If you are going to fly during the winter or at high altitudes, some manufactures recommend baffles, winter fronts and oil cooler kits for their aircraft during low temperature operation. Winterization kits will reduce airflow through the oil cooler and reduce the chance of oil cooler freeze-up. Be sure to remove the winterization kit when it’s no longer needed.

If a winterization kit was installed, was it properly signed-off and placarded? Do you know at what ambient temperature it should be removed? If installation approval is not provided by the kit’s manufacturer, FAA approval may be needed. Read FAA and manufacturer guides, air worthiness manuals and service bulletins to make sure your kit is safe and compliant.

Pre-flight prep

In addition to normal pre-flight checks, check the aircraft for ice or snow, including the propeller blade, flight controls and engine inlets. Even though cold weather does not particularly affect the engine itself, it may cause ice in the fuel lines, control valves, and fuel sumps, and certain parts may need preheating. If ice or snow is found, remove as much as possible by hand and thaw it with heated air or de-icing fluid before attempting to start. Never scrape or chip ice off the aircraft. Make sure frost is thawed from the body, engine and controls, and that windshield anti-ice is used to avoid loss of windshield visibility.

Taxi in normal range

An aircraft should not be taxied until all engine temperatures and systems pressures are within normal range. Taxi at a low speed with wide-radius turns. If the tires are frozen to the runway surface, a slight motion should break them free. If taxiing in soft snow, engage higher than normal power.

If airborne icing occurs

If airborne icing does take place, don’t panic, but take immediate steps to get out of it, especially if the condition is freezing rain or freezing drizzle. Engage the aircraft’s anti-icing equipment, but do not depend on it for prolonged periods, particularly in moderate or heavier ice.

In most cases, an aircraft is flyable in icing conditions, but in a reduced speed range. As icing can increase drag and reduce lift, you may need to increase thrust in order to maintain airspeed.

Whether your small aircraft needs winterizing, maintenance or full-service repair, BAC’s service crew will deliver fast, dependable service to get your airplane flying safely. To learn more about the quality service available from BAC, visit our services page.

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