Failure To Use Deicing Boots Cited in Accident Report

 - January 23, 2007, 10:01 AM

The NTSB determined today that the Feb. 16, 2005 crash of a Circuit City Cessna Citation 560 during the approach to Pueblo Memorial Airport, Colo., was caused because during the approach, as they flew through a cloud containing supercooled liquid droplets, the flight crew didn’t activate the deicing boots at the first sign of ice buildup (as specified in the AFM) and possibly not at all, and didn’t monitor airspeed, which led to a stall. All six passengers and the two pilots were killed in the crash. Contributing to the accident was the FAA’s “failure to establish adequate certification requirements for flight into icing conditions, which led to the inadequate stall warning margin provided by the airplane’s stall warning system.” The investigation determined that the airplane’s stall warning system did not activate until after the stall occurred. The Safety Board did mention that the entire approach up to and including the stall was being flown on autopilot, but didn’t address the safety implications of autopilot use in icing conditions. The Board further concluded that ice bridging “does not occur on modern airplanes; therefore, there is no reason for flight crews to delay activation of the deice boots.”