NTSB Blasts Icing Bridging Belief

 - March 5, 2007, 9:18 AM

The NTSB released new and old recommendations related to the Feb. 16, 2005, stall and fatal crash of a Cessna Citation 560 in Pueblo, Colo. Probable cause was “failure to effectively monitor and maintain airspeed and comply with procedures for deice boot activation on the approach.” Recommendations include training emphasizing boot operation during approach as soon as ice accumulates (as specified in the 560 AFM); requiring revision of AFMs to say that boots should be inflated as soon as the airplane enters icing conditions (a 1998 recommendation); and requiring that boots work automatically after activation. NTSB board member Deborah Hersman wrote that the pilots lacked proper guidance from the FAA and Cessna. There is still widespread belief in the so-called ice-bridging phenomenon, and the 560 AFM tells pilots to wait to inflate boots until ice builds to one-quarter to one-half inch to prevent ice bridging (but not during approach). The Safety Board has long recommended immediate inflation of boots when ice is encountered and has noted repeatedly that ice bridging does not occur.