National Transportation Safety Board (NTSB) Chairman Deborah A.P. Hersman, in recent testimony before the House Aviation Subcommittee, Committee on Transportation and Infrastructure, discussed the dangers of aircraft flying in icing conditions and highlighted longstanding Safety Board recommendations that have yet to be adopted by the Federal Aviation Administration to address the issue, according to a NTSB press release.

Reducing the dangers of flying in icing conditions has been on the NTSB's Most Wanted List of Transportation Safety Improvements since 1997. Last week, the NTSB voted to keep the issue area, along with its four open recommendations to the FAA, on the 2010 Most Wanted List with a "red" classification. The red classification indicates an unacceptable response by the FAA.

"Although the NTSB relies on others to implement these recommendations, we have worked to educate the pilot community about some of the hazards associated with icing conditions through our Safety Alerts," Hersman said.

In 1981, the NTSB published a report titled "Aircraft Icing Avoidance and Protection" and recommended the FAA review icing certification criteria. The special study followed a series of icing-related accidents where aircraft operating in icing conditions and the varying consequences that ice accretion had on different types of aircraft raised concern.

In the 1990s the NTSB re-examined the issue of airframe structural icing and concluded that the icing certification process continues to be inadequate. The Board also became concerned about airplanes that fly in supercooled large droplet conditions and that used pneumatic boots to deice the aircraft in flight. In the last decade, the Board has investigated more than 50 accidents involving aircraft icing, resulting in over 200 fatalities and it continues to investigate accidents where icing is a factor.

In the last few years, the FAA has addressed some of the recommendations related to icing by issuing a number of final and proposed regulations. However, not all of the NTSB's recommendations on icing have been addressed. The full text of Chairman Hersman's testimony is available on the Board's web site at: