Recommends FAA Mandate Auto-Cycling Deicing Boots

On Tuesday, the National Transportation Safety Board issued a sweeping set of recommendations, all stemming from the February 16, 2005 loss of a Cessna Citation near Pueblo, CO. Six Circuit City Stores employees and two pilots were lost in the accident.

As Aero-News reported last month, the Board determined the accident was caused by the flight crew's failure to effectively monitor and maintain airspeed, and comply with procedures for deice boot activation on their approach to Pueblo, CO, which led to an aerodynamic stall. 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.

In addition to recommendations emphasizing additional training on the Cessna 560's deicing systems, and the aircraft's flight characteristics in icing conditions, the Board also recommends the FAA require proper training on all aircraft equipped with pneumatic deicing boots that are certified for flight into known ice (FIKI). Additionally, the NTSB recommends the FAA mandate all booted FIKI-certified aircraft to be equipped with automatic cycling systems, to insure the boots continue to cycle once activated.

The NTSB also noted it continues to recommend revised icing criteria -- to include such factors as liquid water content, and the size of ice and/or waterdrops on a plane's surfaces -- and that freezing rain and mixed ice conditions also be added to the Part 25 Appendix C icing certification envelope. The Board first made those recommendations in 1996.

Below is the text of the NTSB's latest recommendations, which call on the FAA to:

• Require that operational training in the Cessna 560 airplane emphasize the airplane flight manual requirements that pilots increase the airspeed and operate the deice boots during approaches when ice is present on the wings. (A-07-12)
• Require that all pilot training programs be modified to contain modules that teach and emphasize monitoring skills and workload management and include opportunities to practice and demonstrate proficiency in these areas. (A-07-13)
• Require manufacturers and operators of pneumatic deice boot-equipped airplanes to revise the guidance contained in their manuals and training programs to emphasize that leading edge deice boots should be activated as soon as the airplane enters icing conditions. (A-07-14) (This safety recommendation supersedes Safety Recommendation A-98-91 and is classified "Open-Unacceptable Response.")
• Require that all pneumatic deice boot-equipped airplanes certified to fly in known icing conditions have a mode incorporated in the deice boot system that will automatically continue to cycle the deice boots once the system has been activated. (A-07-15)
• When the revised icing certification standards (recommended in Safety Recommendations A-96-54 and A-98-92) and criteria are complete, review the icing certification of pneumatic deice boot-equipped airplanes that are currently certificated for operation in icing conditions and perform additional testing and take action as required to ensure that these airplanes fulfill the requirements of the revised icing certification standards. (A-07-16) (This safety recommendation supersedes Safety Recommendation A-98-100 and is classified "Open-Unacceptable Response.")
• Require modification of the Cessna 560 airplane’s stall warning system to provide a stall warning margin that takes into account the size, type, and distribution of ice, including thin, rough ice on or aft of the protected surfaces. (A-07-17)

In addition, the National Transportation Safety Board reiterates the following recommendations:

• Revise the icing criteria published in 14 Code of Federal Regulations Parts 23 and 25, in light of both recent research into aircraft ice accretion under varying conditions of liquid water content, drop size distribution, and temperature, and recent development in both the design and use of aircraft. Also, expand the Part 25 Appendix C icing certification envelope to include freezing drizzle/freezing rain and mixed water/ice crystal conditions, as necessary. (A-96-54)
• With the National Aeronautics and Space Administration and other interested aviation organizations, conduct additional research to identify realistic ice accumulations, to include intercycle and residual ice accumulations and ice accumulations on unprotected surfaces aft of the deicing boots, and to determine the effects and criticality of such ice accumulations; further, the information developed through such research should be incorporated into aircraft certification requirements and pilot training programs at all levels. (A-98-92)

FMI: www.ntsb.gov