[Federal Register Volume 72, Number 63 (Tuesday, April 3, 2007)]
[Notices]
[Pages 15931-15932]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 07-1620]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

[Docket No. FAA-2007-27758]


Known Icing Conditions

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of draft letter of interpretation.

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SUMMARY: This draft letter of interpretation addresses a request by the 
Aircraft Owners and Pilots Association (AOPA) that the FAA rescind a 
letter of interpretation dated June 6, 2006 regarding ``known icing 
conditions''. Because of the controversy surrounding this issue, the 
FAA is publishing a draft of its response to seek public comment.

DATES: Send your comments on or before May 3, 2007.

ADDRESSES: You may send comments, identified by docket number, using 
any of the following methods:
    1. DOT Docket Web site: Go to http://dms.dot.gov and follow the 
instructions for sending your comments electronically.
    2. Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Room PL-401, Washington, DC 
20590-0001.
    3. Facsimile: (202) 493-2251.
    4. Hand delivery: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Room PL-401, Washington, DC, 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays.
    Privacy: We will post all comments we receive, without change, to 
http://dms.dot.gov, including any personal information you provide.

FOR FURTHER INFORMATION CONTACT: Bruce Glendening, Regulations 
Division, Office of the Chief Counsel, Federal Aviation Administration, 
800 Independence Ave., Washington, DC 20591; telephone (202) 267-3073.

SUPPLEMENTARY INFORMATION: On November 17, 2006, Luis Gutierrez, 
Director of Regulatory and Certification Policy for AOPA, requested the 
FAA's Office of the Chief Counsel rescind a letter of interpretation 
issued by the FAA's Office of the Regional Counsel, Eastern Region, 
regarding flight in known icing conditions. The letter of 
interpretation, dated June 6, 2006, responded to a request by Robert 
Miller that the FAA clarify when ``known ice'' exists for purposes of 
enforcement action.
    The FAA recognizes that the term ``known icing condition'', the 
term 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. Because the FAA has been asked to rescind the June 6, 2006 letter 
of interpretation, we have decided to publish a draft of our response 
in the Federal Register and seek comment on it. Based upon comments 
received in the docket, the FAA may decide to reevaluate its position 
on known icing conditions. The text of the draft response is as 
follows:

Luis M. Gutierrez, Director, Regulatory and Certification Policy, 
Aircraft Owners and Pilots Association, 421 Aviation Way, Frederick, MD 
21701-4798.

Re: Legal Interpretation of Known Icing Conditions

Dear Mr. Gutierrez:

    In a letter dated November 21, 2006, to the FAA Chief Counsel's 
Office, you requested the rescission of a letter of interpretation 
regarding flight in known icing conditions, issued by this office on 
June 6, 2006. The Chief Counsel's Office has referred your letter to us 
for response. After considering the points you and other stakeholders 
have raised, we are replacing our June 6 letter through the issuance of 
this revision.
    Our letter of June 6, 2006, responded to a request by Robert J. 
Miller for a legal interpretation of ``known ice'' as it relates to 
flight operations. We construed the request as seeking clarification of 
the meaning of ``known icing conditions'' as that term appears in the 
Airplane Flight Manuals (AFM) or Pilot Operating Handbooks for many 
general aviation aircraft. That is also the term addressed in legal 
proceedings involving violations of FAA safety regulations that relate 
to in-flight icing. The NTSB has held that known icing conditions exist 
when a pilot knows or reasonably should know of weather reports in 
which icing conditions are reported or forecast.\1\
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    \1\ See e.g., Administrator v. Boger, N.T.S.B. Order No. EA-4525 
(Feb. 14, 1997); Administrator v. Groszer, NTSB Order No. EA-3770 
(Jan. 5, 1993); Administrator v. Bowen, 2 N.T.S.B. 940, 943 (1974).
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    While various FAA regulations contain limitations on flight in 
known icing conditions, the regulatory provision that most commonly 
affects general aviation operators in this respect applies the term 
only indirectly. 14 CFR 91.9 precludes pilots from operating contrary 
to the operating limitations in their aircraft's approved AFM. The 
operating limitations identify whether the aircraft is equipped to 
operate in known icing conditions and may prohibit or restrict such 
flights for many general aviation aircraft. 14 CFR 91.103 requires 
pilots to become familiar with all available information concerning 
their flights before undertaking them.
    Permutations on the type, combination, and strength of 
meteorological elements that signify or negate the presence of known 
icing conditions are too numerous to describe exhaustively in this 
letter. Any assessment of known icing conditions is necessarily fact-
specific. However, the NTSB's decisionmaking reflects the common 
understanding that the formation of structural ice requires two 
elements: visible moisture and an aircraft surface temperature at or 
below zero degrees Celsius. Even in the presence of these elements, 
there are many variables that influence whether ice will actually form 
on and adhere to an aircraft. The size of the water droplets, the shape 
of the airfoil, or the speed of the aircraft, among other factors, can 
make a critical difference in the initiation and growth of structural 
ice.
    Whether 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. The FAA, 
your own association, and other aviation- or weather-oriented 
organizations offer considerable information on the phenomenon of 
aircraft icing. Pilots are encouraged to use this information for a 
greater appreciation of the risks that flying in potential icing 
conditions can present. Likewise, a variety of sources

[[Page 15932]]

provide meteorological information that relates to forecast and actual 
conditions that are conducive to in-flight icing. Pilots should 
carefully evaluate all of the available meteorological information 
relevant to the proposed flight, including applicable surface 
observations, temperatures aloft, terminal and area forecasts, AIRMETs, 
SIGMETs, and pilot reports. As new technology becomes available, pilots 
should incorporate use of that technology into their decision-making 
process.
    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. If the AFM prohibits flight 
in known icing conditions and the pilot operates in such conditions, 
the FAA could take enforcement action.\2\
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    \2\ Enforcement action could also be taken for operation of an 
aircraft into icing conditions that exceed the certification 
limitations of the aircraft.
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    Pilots should also remain aware that 14 CFR Sec.  91.13(a) 
prohibits the operation of an aircraft for the purpose of air 
navigation in a careless or reckless manner so as to endanger the life 
or property of another. Meteorological information that does not 
evidence known icing conditions, or the extent thereof, may regardless 
support a finding that a pilot's operation under the circumstances was 
careless.
    This response constitutes an interpretation of the Chief Counsel's 
Office and was coordinated with the FAA's Flight Standards Service.

    Issued in Washington, DC, on March 27, 2007.
Rebecca MacPherson,
Assistant Chief Counsel for Regulations.
[FR Doc. 07-1620 Filed 4-2-07; 8:45 am]
BILLING CODE 4910-13-M