1 A Study of U. S. Inflight Icing Accidents and Incidents, 1978

334,190 event synopses and reports were screened to yield 9299 relevant reports. These reports were read and disposed into applicability categories. This led to a database of 645 accidents and incidents, and a separate database of 299 NASA Aviation Safety Reporting System reports. The data was analyzed extensively. The principal conclusion was that factors such as pilot training, pilot experience, icing equipage and icing certification are not as significant to icing events as is aircraft scale. Event sequences were modeled; the stall followed by loss of control is the most common occurrence, followed by hard landings. Ice protection systems on smaller aircraft may delay an event but not prevent it. Larger aircraft are more likely to encounter an icing event on final approach or during the landing. Freezing precipitation is present in 33 % of the total events in the data. Snow is present in 32 % of the events; these conditions are not mutually exclusive, as 7 % of the events include both. Surface weather observations including temperatures of near freezing and ceiling of one thousand feet or less are generally associated with icing events