Mailing List lml@lancaironline.net Message #41661
From: Kevin Kossi <kevin@airforcemechanical.com>
Sender: <marv@lancaironline.net>
Subject: FAA's draft letter of interpretation ‘‘known icing condition’’
Date: Wed, 18 Apr 2007 20:38:55 -0400
To: <lml@lancaironline.net>
This is an improvement!

Kevin Kossi
Legacy N77PX

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.
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.

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
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
VerDate Aug<31>2005 18:30 Apr 02, 2007 Jkt 211001 PO 00000 Frm 00072 Fmt 4703 Sfmt 4703 E:\FR\FM\03APN1.SGM 03APN1 ycherry on PROD1PC64 with NOTICES
15932 Federal Register / Vol. 72, No. 63 / Tuesday, April 3, 2007 / Notices
2 Enforcement action could also be taken for
operation of an aircraft into icing conditions that
exceed the certification limitations of the aircraft.
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
Pilots should also remain aware that
14 CFR ¤ 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]


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