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Proposed Rule

Mode S Transponder Requirements in the National Airspace System

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Federal Aviation Administration (FAA), DOT.

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Policy notice and disposition of comments.


On October 7, 2005, the Federal Aviation Administration (FAA) published a document in the Federal Register announcing its long-term policy for Mode S transponder equipment requirements. The policy also sought comment on the proposed termination date of March 1, 2007, for operators currently exempted from the Mode S transponder requirement of 14 CFR parts 121 and 135. This action responds to the comments and adopts the proposed date for which all applicable exemptions will terminate.


The complete docket for the proposed exemption policy may be examined at the DOT Docket Web site: Interested persons may perform a Simple Search at that Web site, entering the docket number 22593. Comments may also be examined in Room PL-401, on the Plaza Level of the Department of Transportation Building, 400 Seventh Street, SW., Washington, DC between 9 a.m. and 5 p.m., except Federal holidays.

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Ida Klepper, Office of Rulemaking, Federal Aviation Administration, 800 Independence Avenue SW., Washington, DC 20591, telephone (202) 267-9677.

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On October 7, 2005, the FAA published two notices in the Federal Register concerning the Mode S transponder equipment requirements in 14 CFR parts 121 and 135. The first notice withdrew Notice No. 96-5, which proposed to withdraw the Mode S transponder requirements for part 135 and certain 121 operations. The first October 7 notice summarized our reassessment of the requirements and articulated the basis for our conclusion to retain the Mode S transponder equipment requirements. (See 70 FR 58966.) Accordingly, the FAA withdrew Notice No. 96-5.

The second notice published on October 7 announced our policy with respect to the exemptions granted from the Mode S transponder equipment requirements. (See 70 FR 58976.) We explained that since Notice 96-5 was published in May 1996, the agency granted several exemptions to the Mode S transponder requirements because we were progressing toward the removal of this equipment requirement from all aircraft, except those aircraft operated under part 121 and that have TCAS II. As we subsequently revised our long-term plan for Mode S transponders, we sought comment on the appropriate date for which all current exemptions should terminate. The notice proposed March 1, 2007, as the appropriate termination date.

Discussion of Comments

We received comments from AirTran Airways, Inc., Federal Express (FedEx), the Regional Airlines Association (RAA), and one individual. However, while the notice specifically sought comment on whether March 1, 2007 was the appropriate date to terminate current exemptions, no comment responded to that request. Although all comments were beyond the scope of the request, we respond to those comments below.

AirTran Airways fully supported that all applicable aircraft comply with the Mode S transponder equipment requirements.

FedEx commented on two aspects of the notice. First, it questioned whether it must request an extension of its current exemption to continue to use the Mode C and Mode A transponders installed on its Caravan airplanes until March 1, 2007. (FedEx's exemption expires on March 1, 2006.) Second, FedEx stated that it has both Mode A and Mode C transponders installed on its Caravan airplanes. FedEx questioned whether it must replace each transponder with a separate Mode S transponder.

The FAA does not intend to grant new exemptions or subsequent extensions of current exemptions during this interim period unless circumstances warrant. FedEx may continue to operate its Caravan airplanes with Mode A and Mode C installed, even after expiration of its exemption, until the transponders are no longer repairable and must be replaced. If FedEx finds that the transponders must be replaced after its exemption terminates, it must do so in accordance with the regulations and install a Mode S transponder. The FAA proposed the March 2007 date to provide a reasonable time for operators to plan for the need to replace outdated equipment when necessary. The FAA did not suggest this date to provide a vehicle for operators to quickly seek an exemption or extension to bide more time for which to equip their aircraft. We do not find that the public interest is served by simply granting additional exemptions for yet another year.

It appears to be a business decision by FedEx to have two transponders installed in its aircraft. This is not a regulatory requirement. Consequently, if FedEx needs to install a Mode S transponder in its aircraft, it only needs to install one transponder under the regulations. Any election to install a second transponder is at FedEx's discretion.

An individual commented that the ADS-B system is far superior to Mode S because it has the capability to receive other traffic and weather information and urged the adoption of a nationwide Capstone policy to benefit all operators (including general aviation) as opposed to enforcing outdated Mode S equipment. Also, RAA commented it would expect the Mode S requirement to be consistent with the FAA's long term objectives for ADS-B to avoid costly retrofits.

Capstone is a successful initiative, but is a limited concept for a defined and remote area in southwest Alaska. Capstone does not rely on ADS-B technology but rather on Global Positioning Systems (GPS) and Wide Area Augmentation Systems (WAAS) in areas where ground sensors are not yet available. ADS-B is not considered an alternative to the more mature Mode S technology at this time due to the uncertain timeframe of widespread availability of the technology. FAA plans for expanding the ADS-B technology to the lower 48 states are still under review. Lastly, any requirement to equip and use ADS-B technology must be established through rulemaking.

RAA requested that the agency complete a cost benefit analysis of the Mode S policy and provide an opportunity for public comment on that analysis.

The FAA is required to economically analyze its intended regulations.[1] (A regulatory evaluation, including cost-benefit analysis, was completed for both the final rule adopting the Mode S requirement [2] and the notice proposing to withdraw the requirement.[3] ) The FAA is not required to conduct an economic review because it determines not to proceed with a proposed regulation. A number of exemptions were granted between 1996 and 2005. The FAA could have simply denied all requests for exemptions until the Mode S transponder equipment requirement was in fact rescinded. However, we did not view this as supporting the public interest and concluded that certain exemptions were justified given the agency position on Mode S in 1996. Several operators have benefited from Start Printed Page 7894the exemptions and were able to defer the equipage costs for several years. Since that time, technology developments and the availability of Mode S avionics dictate that we revise our policy. As we are retaining the Mode S transponder requirements, the basis for the current exemptions no longer exists. Operators are not entitled to an exemption as a matter of right. Consequently, we do not agree with RAA's assertion that the previous grant of exemptions is tantamount to a rule and thus deserving of a cost-benefit analysis. We did view, as critical and warranting public input, the appropriate date for which the exemptions would terminate and that affected operators would be required to install a Mode S transponder if their Mode C or Mode A transponder could not be repaired and specifically requested comment on that aspect.

RAA also stated that there are more than 130,000 general aviation users who are not required to install Mode S and questioned why the Mode S transponder are required for part 135 operators.

The Mode S transponder requirement for part 91 operations was rescinded in 1992 (57 FR 34614; August 5, 1992). The agency concluded that the expense of requiring the equipment for all part 91 operators could not be justified since the vast majority of general aviation operators do not operate in congested airspace. Furthermore, to impose a Mode S requirement on all such operators would be unduly burdensome with little safety benefit. At this time, we do not see evidence that this rationale is no longer valid.

As stated previously, any new exemption or request for extension will be evaluated carefully as to whether it would serve the public interest. Requesting an exemption simply because previous exemptions have been granted is not considered in the public interest.

Adoption of the March 1, 2007 Date

The FAA concludes that March 1, 2007, provides a reasonable timeframe for the exemptions to terminate. We intend to judiciously exercise our authority in reviewing any petitions for exemption or requests for extension under 14 CFR 11.81.

Operators are advised that this policy does not require the installation of Mode S transponders on March 1, 2007. Operators may continue to use Mode A and Mode C transponders beyond the expiration of their exemption and past March 1, 2007, until they can no longer be repaired and must be replaced.

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Issued in Washington, DC, on February 9, 2006.

James J. Ballough,

Director, Flight Standards Service.

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1.  Executive Order 12866, Regulatory Flexibility Act of 1980 (5 U.S.C. 5601, et seq.), Trade Agreements Act (19 U.S.C. 4 §§ 2531-2533, Unfunded Mandate Reform Act of 1995 (Pub. L. 104-4).

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2.  52 FR 3380; February 3, 1987.

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3.  61 FR 26036; May 23, 1996.

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[FR Doc. E6-2178 Filed 2-14-06; 8:45 am]