Avsoft has updated all Holdover Time (HOT) tables depicted in its Cold Weather Operations (CWO) course as per the “FAA Holdover Time Guidelines Winter 2019-2020” document; these tables are featured throughout the De-icing and Anti-icing Procedures module of the CWO course. HOT tables show the estimated times that a generic or specific type of de-icing/anti-icing fluid will prevent the accumulation of snow and the formation of ice or frost on aircraft critical surfaces, based on fluid/water concentration, outside air temperature, and type of precipitation.
When ice accretes and accumulates on aircraft critical surfaces, it disrupts the airflow around the aircraft, significantly reducing lift and increasing drag. This loss in aerodynamic performance has caused or been a major factor in many aviation accidents that have occurred in icing conditions. On March 22, 1992, USAir Flight 405 crashed shortly after departing from LaGuardia Airport in New York. The National Transportation Safety Board (NTSB) concluded in its report that “ice contamination on the wings resulted in an aerodynamic stall and loss of control after liftoff.” Of the 51 people on board the Fokker F28-4000 Fellowship aircraft, 27 were killed, including the captain and a cabin crew member.
HOT tables are vitally important to safe aircraft operations in cold weather, as they provide flight crews with safe holdover times. If a holdover time has expired, an aircraft should not take off until a pre-take-off contamination inspection is conducted and the critical surfaces are determined to be not contaminated. If the critical surfaces are contaminated, the aircraft must be de-iced or anti-iced again before take-off. The FAA updates its HOT tables each year before the northern winter season. ICAO and EASA consider “FAA Holdover Time Guidelines” documents to be acceptable reference for use by airline operators.
Avsoft’s Cold Weather Operations aviation training course provides a comprehensive introduction and review of the components, concepts, definitions, limitations, and procedures related to this important subject. This course is designed to provide initial training for pilots and dispatchers. Customers can tailor this course to fit their recurrent training requirements.
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