The FAA’s Office of Chief Counsel today published a Draft Letter of Interpretation regarding “known icing conditions”. The Letter is a response to an AOPA request that the Chief Counsel’s office rescind an earlier letter of interpretation issued by the Eastern Region that defined “known icing conditions” in a manner that could have the effect of placing severe constraints on when individuals in aircraft without deicing equipment could fly. (The Eastern Region stated that “high relative humidity” constitutes known icing conditions, which meant that in high relative humidity conditions when the temperature is near or below freezing, pilots would have to fly an aircraft with deicing equipment.) Rather than rescinding this narrow interpretation, the Chief Counsel’s office published a draft interpretation seeking comments on its proposed interpretation of the term “known icing conditions”.
Although the Letter appears to remove the rigidness of the Eastern Region’s interpretation, it doesn’t provide a precise definition of what constitutes “known icing conditions”. The Letter begins its analysis by restating the NTSB precedent which provides that “known icing conditions exist when a pilot knows or reasonably should know of weather reports in which icing conditions are reported or forecast”. It then states that any assessment of “known icing conditions” is fact-specific and “[w]hether a pilot has operated into known icing conditions contrary to any limitation will depend upon the information available to the pilot, and his or her proper analysis of that information in connection with the particular operation (e.g., route of flight, altitude, time of flight, airspeed, and aircraft performance characteristics), in evaluating the risk of encountering known icing conditions.”
Known icing conditions will likely exist “[i]f the composite information indicates to a reasonable and prudent pilot that he or she will encounter visible moisture at freezing or near freezing temperatures and that ice will adhere to the aircraft along the proposed route and altitude of flight.” The Letter also reiterates that a pilot has a duty to evaluate the weather conditions both before an anticipated flight, as well as continuously during a flight. Clear as mud, right?!
At the end of the day, I am not sure this Letter helps much, other than removing the “high relative humidity” restricting language. Pilots will still need to evaluate all available information both before and during a flight in order to make a reasonable determination as to whether “known icing conditions” are present along the proposed route of flight.
Comments to the draft letter are due no later than May 3, 2007 and depending upon the comments received, the FAA could decide to re-evaluate its position on known icing conditions. If you would like further information, you may contact Bruce Glendening, Regulations Division, Office of the Chief Counsel, Federal Aviation Administration, 800 Independence Ave., Washington, DC 20591; telephone (202) 267-3073.