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Statistical Study of Aircraft Icing Probabilities at the 700- and 500- Millibar Levels over Ocean Areas in the Northern HemisphereA statistical study is made of icing data reported from weather reconnaissance aircraft flown by Air Weather Service (USAF). The weather missions studied were flown at fixed flight levels of 500 millibars (18,000 ft) and 700 millibars (10,000 ft) over wide areas of the Pacific, Atlantic, and Arctic Oceans. This report is presented as part of a program conducted by the NACA to obtain extensive icing statistics relevant to aircraft design and operation. The thousands of in-flight observations recorded over a 2- to 4-year period provide reliable statistics on icing encounters for the specific areas, altitudes, and seasons included in the data. The relative frequencies of icing occurrence are presented, together with the estimated icing probabilities and the relation of these probabilities to the frequencies of flight in clouds and cloud temperatures. The results show that aircraft operators can expect icing probabilities to vary widely throughout the year from near zero in the cold Arctic areas in winter up to 7 percent in areas where greater cloudiness and warmer temperatures prevail. The data also reveal a general tendency of colder cloud temperatures to reduce the probability of icing in equally cloudy conditions.
Document ID
19810068859
Acquisition Source
Legacy CDMS
Document Type
Other - NACA Technical Note
Authors
Perkins, Porter J. (National Advisory Committee for Aeronautics. Lewis Flight Propulsion Lab. Cleveland, OH, United States)
Lewis, William (National Advisory Committee for Aeronautics. Lewis Flight Propulsion Lab. Cleveland, OH, United States)
Mulholland, Donald R. (National Advisory Committee for Aeronautics. Lewis Flight Propulsion Lab. Cleveland, OH, United States)
Date Acquired
August 11, 2013
Publication Date
May 1, 1957
Subject Category
Meteorology And Climatology
Report/Patent Number
NACA-TN-3984
Accession Number
81N73281
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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