Air Safety Institute Safety Spotlight
Just because you're flying in clear air doesn't guarantee your safety from icing--at least carburetor icing. On November 11, 2001, the pilot of a Piper Cherokee was killed and his passenger seriously injured during a night forced landing after losing engine power.
About three hours into the until-then-uneventful night flight, the pilot contacted Mansfield, Ohio, approach control, said that he was experiencing a partial power loss, and asked to land at Mansfield. Mansfield's Runway 32 was four miles straight ahead, and the pilot was cleared to land. According to the passenger, the pilot applied carburetor heat for about 10 seconds, and with no change in engine operation, returned it to cold and said that he thought they were experiencing vapor lock. Shortly thereafter, the pilot informed Mansfield Approach that the engine had quit and he was going to land on a road.
Investigation revealed that the temperature and dew point spread had decreased as the flight progressed. At the time of the accident, the temperature in Mansfield was minus 1 degree Celsius (30.2 degrees Fahrenheit) and the dew point was minus 4 degrees C (24.8 degrees F).
The NTSB determined the cause of this accident to be the pilot's improper use of carburetor heat and the subsequent forced landing.
Avoid problems of this nature by taking advantage of the free advice in the AOPA Air Safety Foundation's Aircraft Icing Safety Advisor. It says, "At the first indication of carburetor ice, apply full carburetor heat and leave it on. The engine may run rougher as the ice melts and goes through it, but it will smooth out again."
A carburetor icing probability chart (above) is one of the tools in the Aircraft Icing Safety Advisor that could have helped this pilot.
Kristen Hummel manages the GA accident database for the AOPA Air Safety Foundation. She holds a commercial pilot certificate with multiengine and instrument ratings.
By Kristen Hummel