New FAA Icing Definition is a Cloud of Confusion

Some point out that if the FAA sticks to its interpretation then most general aviation aircraft would be grounded for the winter.


WASHINGTON – A simple letter last June to a pilot seeking clarification on flying in "known icing conditions" has opened a can of worms for the Federal Aviation Administration.

The FAA on April 3 released a draft letter to the Aircraft Owners and Pilots Association (AOPA) which re-evaluates the language and definitions contained in the June letter. Of note, the FAA does not fall back to its long-standing guidance, but instead crafts new instructions to pilots. In the days that the draft has been posted on the FAA web site, the revised language has only drawn more criticism.

Some point out that if the FAA sticks to its interpretation then most general aviation aircraft would be grounded for the winter.

"The FAA recognizes that the term 'known icing conditions,' addressed in the June 2006 letter of interpretation, could be misconstrued. Based on one's interpretation of the term, the FAA's prohibitions against flying into known icing conditions under certain circumstances could either have the effect of placing severe constraints on when individuals in aircraft without deicing equipment could fly or allowing these individuals to fly in conditions where there is a real risk of ice accretion with no means of removing the ice," the FAA wrote as a prelude to its draft letter.

The key paragraph of the draft letter attempts to clarify "known icing conditions," it reads in part: "The ultimate decision whether, when, and where to make the flight rests with the pilot. A pilot also must continue to reevaluate changing weather conditions. If 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, then known icing conditions likely exist."

The clarification is "too vague, too broad, and too likely to invite subjective judgment," said John Hazlet, a vice president with California-based Ameriflight and a vice president with the Regional Air Cargo Carriers Association (RACCA).

"The only way to prove that icing conditions exist is to encounter them – as has been proven repeatedly over decades of flying," Hazlet noted.

As a suggestion, RACCA wants the phrase "then known icing conditions likely exist" to be replaced with a directive that a pilot should plan for alternative courses if actual icing is encountered. Furthermore, Hazlet suggests that the FAA go back to language in a 1981 advisory letter which stated that aircraft can depart when light or moderate icing is forecast, but the pilot can not continue to fly in actual icing conditions.

AOPA has not filed its formal comments on the new language; however, the group does like the new FAA interpretations, said Kathleen Vasconcelos, an AOPA spokesperson. "They are saying that it is up to the pilot to decide whether to fly or not when icing conditions will be encountered. We support that. We believe it should be up to the pilot to make that go/no go decision," she told AMT Online.

AOPA did not have any disagreement with FAA's long-standing policy on flying during potential icing conditions, she said. The language prior to the June letter stated that the decision was up to the pilot and now the new one also does. "It has come full circle," Vasconcelos said.

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