
[Federal Register Volume 77, Number 94 (Tuesday, May 15, 2012)]
[Notices]
[Pages 28668-28669]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-11678]



[[Page 28668]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Technical Standard Order (TSO)-C91a, Emergency Locator 
Transmitters (ELTs)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of cancellation of Technical Standard Order (TSO)-C91a, 
Emergency Locator Transmitter (ELT) Equipment.

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SUMMARY: This notice announces the FAA's cancellation of TSO-C91a, 
Emergency Locator Transmitter (ELT) Equipment. The effect of the 
cancelled TSO will result in no new TSO-C91a design or production 
approvals being issued. Applicants wanting to apply for TSO 
Authorization (TSOA) for new Emergency Locator Transmitters (ELTs) 
after December 1, 2012, must seek authorization for TSO-C126a, 406 MHz 
Emergency Locator Transmitter (ELT), or subsequent.

FOR FURTHER INFORMATION CONTACT: Mr. Albert Sayadian, AIR-130, Federal 
Aviation Administration, 470 L'Enfant Plaza, Suite 4102, Washington, DC 
20024. Telephone (202) 385-4652, fax (202) 385-4651, email to: 
Albert.Sayadian@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

    On February 1, 2009 Cospas-Sarsat satellite system stopped 
processing signals from 121.5 MHz ELTs and now only processes signals 
from 406 MHz ELTs. The decision to discontinue processing of the 121.5 
MHz signal was made by the International Cospas-Sarsat program with 
guidance from the United Nations. This was made due to the problems 
within the 121.5 MHz frequency band which inundated SAR authorities 
with reports of poor accuracy and numerous false alerts, thus impacting 
the effectiveness of lifesaving services.
    The 406 MHz ELT technology is an advance over the older 121.5 MHz 
ELT technology. TSO-C126a ELT equipment is more accurate and reliable 
than the 121.5 MHz ELT equipment. Examples of these improvements are: 
(1) Global satellite coverage; (2) a unique beacon identification which 
is required to be registered so that if an alert is activated the 
rescue coordination center can confirm whether the distress is real, 
who they are looking for, and where the search should begin; (3) 406 
MHz ELTs can be received by geostationary satellites which are always 
visible and provide instantaneous alerting, and (4) increased position 
accuracy which reduces the search area to less than two nautical miles 
in radius. Additionally, 406 MHz ELTs can optionally include a GPS 
position which can potentially reduce the search area to within 100 
meters of the accident site.
    The performance and benefits of TSO-C126a equipment surpasses TSO-
C91a equipment. The 406 MHz technology is mature and prevalent in the 
ELT market today. New TSO authorizations for ELTs should be 
accomplished to TSO-C126a, or subsequent, thus the FAA is canceling 
TSO-C91a.

Comments

    On January 11, 2012, a notice was published in the Federal Register 
which requested comments on the cancellation of TSO-C91a (77 FR 1779).
    The FAA received comments from four organizations in response to 
the Federal Register Notice. Comments from Cobham Beacon Products were 
comprised of several questions. The first question regarded 
permissibility of minor and major changes to existing TSO-C91a designs. 
In response, minor changes to an existing TSO-C91a ELT design will 
still be allowed in accordance with Title 14 of the Code of Federal 
Regulation (14 CFR) 21.611(a), however, after December 1, 2012, a major 
change that is extensive enough to require issuance of a new ELT TSO 
authorization will have to meet the minimum performance standards 
contained in TSO-C126a. Cobham's second question requested 
clarification on repair and overhaul of TSO-C91a ELTs. The FAA 
clarifies that repair and overhaul of TSO-C91a articles will continue 
to be permissible. Cobham's third question involved permissibility of 
continued installation of TSO-C91a ELTs. The FAA reiterates that 
articles with previous TSO-C91a authorizations may still be produced, 
sold, and installed. Cobham also inquired if the FAA will update 14 CFR 
Sec.  91.207 to exclude TSO-C91a equipment if the Federal Communication 
Commission (FCC) changes the rules governing the 121.5 MHz frequency. 
The FAA can not comment on future FCC actions, however at this time the 
FAA has no plans to revise 14 CFR 91.207.
    The second commenter, Astronics DME Corporation, provided two 
comments. First, Astronics commented that cancellation of TSO-C91a 
eliminates procedural access to the TSO requirements of 14 CFR 21, 
Subpart O when a major change to the TSO's article is required. Under 
14 CFR Part 21, a major change requires the TSO authorization holder to 
apply for a new TSO authorization utilizing the latest revision of the 
TSO. Major changes to TSO-C91a articles will be accepted when applied 
for utilizing the latest revision of TSO-C126.
    Astronics also commented that elimination of satellite detection on 
the 121.5 MHz frequency is not sufficient justification for TSO-C91a 
cancellation. The FAA acknowledges that the 121.5 MHz ELT signal is 
still monitored in many cases and provides limited search and rescue 
functionality. However, TSO-C126a is a more mature standard, and the 
406 MHz signal provides satellite detection, which enhances search and 
rescue efforts. Because the 121.5 MHz ELT continues to provide this 
basic functionality, the TSO-C91a ELTs can continue to be used to meet 
14 CFR Sec.  91.207, however because a more mature standard is 
available, it is appropriate to require new ELTs designs to meet the 
standards of TSO-C126a, or subsequent.
    Astronics also commented that the TSO-C126a requirement to include 
a 121.5 MHz homing beacon in the 406 MHz ELT should be modified to 
allow manufacturers to include a GPS locator instead of the 121.5 
homing beacon. The FAA acknowledges the benefits of including GPS 
position with the 406 MHz ELT transmission, and encourages this 
optional capability. However, this action is canceling TSO-C91a, and is 
not modifying TSO-C126a.
    The General Aviation Manufacturers Association (GAMA) and the 
Aircraft Owners and Pilots Association (AOPA) both provided comments 
that they do not oppose the TSO-C91a cancelation, but that they would 
oppose any future retrofit requirement. Both organizations requested 
the FAA reiterate that cancelation of TSO-C91a does not impact the 
continued production of articles with an existing TSO authorization nor 
impact the sale, installation, or the use of 121.5 MHz ELTs to comply 
with 14 CFR 91.207.
    The General Aviation Manufacturers Association (GAMA) also 
conducted a survey of the manufacturers of general aviation aircraft 
and determined that all current production airplanes include dual or 
tri-band ELTs. Additionally, these dual or tri-band ELTs have been 
installed in new production airplanes for over the past 5-years.
    The FAA reiterates in this final notice that cancelation of TSO-
C91a does not affect production under an existing TSO authorization. 
Articles produced under an existing TSO-C91a authorization can still be 
installed according to existing airworthiness approvals and 
applications for new installation approvals will still be processed. 
This

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action does not impact operation of TSO-C91a ELTs, and these ELTs will 
continue to satisfy the 14 CFR 91.207 ELT equipage requirement.
    GAMA also commented that the FAA should reconsider the ELT 
operational mandate as newer technology, such as ADS-B, becomes more 
commonplace. The FAA has determined that the ADS-B system currently 
cannot replace the ELT function. The ADS-B system is not required to be 
crashworthy and, thus, may not be operable or able to transmit 
following an aircraft accident. Additionally, current search-and-rescue 
technology is not compatible with ADS-B operations because ELTs 
broadcast on 121.5 or 406 MHz (not 1090 or 978 MHz). The FAA recognizes 
the value of a ground application that could allow for timely and 
accurate flight tracking of downed aircraft and is evaluating this 
capability separate from this action.

Conclusion

    TSO-C91a is canceled effective December 1, 2012. Manufacturers 
applying for new ELT technical standard order authorizations after 
December 1, 2012 must use TSO-C126a, or a subsequent ELT technical 
standard order.

    Issued in Washington, DC, on May 9, 2012.
Susan J.M. Cabler,
Assistant Manager, Aircraft Engineering Division, Aircraft 
Certification Service.
[FR Doc. 2012-11678 Filed 5-14-12; 8:45 am]
BILLING CODE 4910-13-P


