[Federal Register Volume 64, Number 239 (Tuesday, December 14, 1999)]
[Notices]
[Pages 69812-69813]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-32481]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
Draft Advisory Circular (AC) 91-XX, Altimeter Errors At Cold
Temperatures
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of availability and request for comments.
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[[Page 69813]]
SUMMARY: This notice announces the availability of and request for
comments on proposed AC 91-XX, which provides information and pilot/
controller guidance about a potentially hazardous situation with
altimeters that occurs at extreme temperatures. Now that international
standards have matured to a level of confidence, it is important that
cold temperature correction procedures be implemented in the national
airspace system. This action is being taken to address Controlled
Flight Into Terrain (CFIT) issues and support the Administrator's
safety agenda.
DATES: Comments must be received on or before January 28, 2000.
ADDRESSES: Send all comments on the proposed AC to: Howard Swancy,
Flight Procedures Standards Branch (AFS-420), Federal Aviation
Administration, 800 Independence Avenue, SW., Washington, DC 20591;
telephone number: (202) 267-8724.
FOR FURTHER INFORMATION CONTACT: Howard Swancy, Flight Procedures
Standards Branch (AFS-420), Federal Aviation Administration, 800
Independence Avenue, SW., Washington, DC 20591; telephone number: (202)
267-8724.
SUPPLEMENTARY INFORMATION:
Comments Invited
A copy of the draft AC may be obtained by accessing the FAA's
webpage at http://www.faa.gov/avr/arm/nprm/nprm.htm. Interested parties
are invited to submit comments on the proposed AC. Commenters must
identify AC 91-XX, and submit comments to the address specified above.
All communications received on or before the closing date for comments
will be considered by the FAA before issuing the final AC.
Discussion
The effect of cold temperature on altimeters has been the subject
of intense study and analysis since the early days of aviation. These
study results indicate that a number of aircraft accidents can be
attributed solely to pilot failures to set or use the altimeter
correctly. Although, there have been no accidents occurring in the
Unites States being directly related to a cold altimeter error, studies
confirm a number of near tragic events being thwarted in the final
seconds.
Cold temperatures tend to induce altimeter error that, in turn,
could potentially pose a deadly threat to today's aviators worldwide.
At extreme temperatures, altimeters may give pilots significantly
erroneous readings. The situation is especially dangerous at cold
extremes because altimeters may indicate altitudes higher than the
aircraft's actual altitude. This error might be as much as 1000 feet or
more. A pilot may not maintain an altitude necessary to clear
obstructions when relying solely on the altimeter reading and flying in
extreme cold temperatures.
The subject of cold temperature altimeter errors has been studied,
by world experts, and is considered to be a primary factor facilitating
CFIT mishaps. In the interest of safety, every pilot must understand
and know procedures to make altitude adjustments as appropriate for
actual flight conditions.
Issued in Washington, DC, on December 9, 1999.
L. Nicholas Lacey,
Director, Flight Standards Service.
[FR Doc. 99-32481 Filed 12-13-99; 8:45 am]
BILLING CODE 4910-13-M
