[Federal Register Volume 88, Number 120 (Friday, June 23, 2023)]
[Rules and Regulations]
[Pages 41023-41024]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-12607]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 91

[Docket No.: FAA-2022-1212]


Changes to Surveillance and Broadcast Services

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notification of changes to surveillance services.

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SUMMARY: This document announces termination of the Mode-S Traffic 
Information Service (TIS) at FAA terminal Mode-S radar sites. The FAA 
is replacing legacy terminal Mode-S radars via the Mode-S Beacon 
Replacement System (MSBRS) program, or may remove legacy terminal Mode-
S radars as part of other ongoing activities. As each legacy terminal 
Mode-S Radar is replaced or removed, the FAA will no longer provide 
Mode-S TIS to capable transponders from that location. This change does 
not affect existing Traffic Information Service--Broadcast (TIS-B), 
Automatic Dependent Surveillance--Rebroadcast (ADS-R), or Automatic 
Dependent Surveillance--Same Link Rebroadcast (ADS-SLR) services 
currently provided to aircraft with a properly functioning Automatic 
Dependent Surveillance--Broadcast (ADS-B) system.

DATES: Effective June 23, 2023.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning 
this document, contact: Michael Freie, Technical Advisor, Surveillance 
Services, AJM-4, Air Traffic Organization, Federal Aviation 
Administration, 600 Independence Avenue SW, Washington, DC 20597; 
telephone: 202-528-2337; email: [email protected].

SUPPLEMENTARY INFORMATION: 

Executive Summary

    In 2018, the FAA performed an assessment of the safety impacts on 
general aviation owners and operators (from here on referred to as 
``the GA Community'') from the termination of Mode-S Traffic 
Information Service (TIS). The purpose of this work was to communicate 
information on the removal of Mode-S TIS from the National Airspace 
System (NAS) through user outreach and engaging with non-governmental 
organizations (e.g., Aircraft Electronics Association (AEA), Aircraft 
Owner and Pilots Association (AOPA), Experimental Aircraft Association 
(EAA), and General Aviation Manufacturers Association (GAMA)). Taking 
into consideration the results of the FAA study and the benefits from 
the ADS-B In traffic services available in the NAS, the FAA determined 
that removal of Mode-S TIS had little to no significant adverse safety 
impact on the GA Community. Therefore, beginning in 2024, Mode-S TIS 
will terminate at each radar location as current Mode-S radars are 
replaced by the Mode-S Beacon Replacement System (MSBRS) program, or as 
legacy terminal Mode-S radars are removed as part of other ongoing 
activities. The GA Community should no longer rely on reception of 
Mode-S TIS information from FAA capable radars.

I. Background

    In 2000, FAA implemented Mode-S Traffic Information System (TIS) 
via Mode-S radar data-link functionality. Mode-S TIS has also been 
referred to informally as TIS-A by some in industry. Mode-S TIS was 
implemented by FAA in response to an NTSB recommendation suggesting 
improvement of situational awareness information for the general 
aviation (GA) community not equipped with a traffic alert and collision 
avoidance system (TCAS). Reception of Mode-S TIS information was not a 
functionality that was required for Mode-S transponders. To this day, a 
very limited set of transponders are known to be capable of receiving 
and processing Mode-S TIS information from FAA terminal radars.
    In May 2010, the FAA published 14 CFR 91.225 and 91.227, requiring 
aircraft to be equipped with Automatic Dependent Surveillance--
Broadcast (ADS-B) Out equipment by 1 January 2020 in order to operate 
in certain U.S. airspace. ADS-B was identified as the backbone for the 
future of the FAA's Next Generation (NextGen) programs. From 2010 
through 2020, the FAA funded deployment of approximately 700 ADS-B 
radio stations across the U.S. to provide improved surveillance 
coverage across the NAS. Along with improving surveillance coverage, 
the FAA implemented functionality into ADS-B radio stations geared at 
providing appropriately equipped GA aircraft with enhanced situational 
awareness through both Traffic Information Services--Broadcast (TIS-B) 
and Automatic Dependent Surveillance--Rebroadcast (ADS-R).\1\ In 2016, 
FAA funded the addition of Automatic Dependent Surveillance--Same Link 
Rebroadcast (ADS-SLR) service at the busiest U.S. airports with a 
surface surveillance system.\2\
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    \1\ More information on TIS-B and ADS-R can be found at the 
FAA's NEXTGEN ADS-B website: https://www.faa.gov/nextgen/programs/adsb.
    \2\ FAA has two surface surveillance systems: ASSC (Airport 
Surface Surveillance Capability) and ASDE-X (Airport Surface 
Detection Equipment, Model X). See https://www.faa.gov/nextgen/programs/adsb/atc/assc and https://www.faa.gov/air_traffic/technology/asde-x.
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    In the decades following the initial Mode-S TIS deployment, the FAA 
implemented improved systems for provisioning information on proximate 
aircraft to GA pilots through the use of TIS-B, ADS-R, and ADS-SLR 
services. These new services expand beyond the

[[Page 41024]]

currently provided Mode-S TIS. With the ADS-B mandate in effect since 
January 2020, and low-cost avionics systems for receiving and 
displaying ADS-B, ADS-R, ADS-SLR, and TIS-B information are readily 
available, the GA community is able to obtain a heightened situational 
awareness of the traffic around them. This is especially true when 
flying around the terminal areas where significant ADS-B coverage is 
available today.
    As of March 6, 2023, approximately 133,486 aircraft have been 
identified as receiving ADS-B In information on one or both of the 
mandated ADS-B frequencies. The vast majority of these are general 
aviation aircraft due to the number of portable ADS-B In devices or 
integrated ADS-B In/Out systems available to this market.

Mode-S Radar Beacon Replacement System

    Many FAA Mode-S terminal radars are approaching the end of their 
useful lifecycle. Additionally, the FAA is facing an increased 
maintenance cost from the inability to purchase parts, due to parts 
obsolescence or part shortages, necessary to ensure continued 
operational availability. To mitigate this, the FAA has initiated a 
radar modernization effort called the Mode-S Beacon Replacement System 
(MSBRS) program. Under this program, the FAA intends to replace at 
least forty-six (46) aging Mode-S terminal radars starting in 2024. 
Starting in 2024 as the new MSBRS radars replace the existing terminal 
radars, the existing Mode-S TIS functionality will disappear at the 
location of each replaced terminal radar.
    Replacement of the existing terminal radars capable of providing 
Mode-S TIS under the MSBRS Program will provide an improvement in air 
traffic control (ATC) capabilities, which will benefit civil and 
military aviation, including general aviation. Installation of the new 
state-of-the-art MSBRS radars will improve system operational 
reliability and reduce system down time.
    During this timeframe, the FAA will continue to provide Mode-S TIS 
through the existing terminal radars until the existing radar is 
replaced with a new MSBRS radar. This document is intended to provide 
time for GA aircraft owners and operators who have not yet equipped 
with an ADS-B receiver to acquire and install, if appropriate, an ADS-B 
In capable system.

Other FAA Surveillance System Improvement Activities

    Independent of the MSBRS program, FAA is also engaged in multiple 
activities aimed at improving existing surveillance systems. These 
activities are aimed at reducing FAA operating costs and/or reducing 
congestion on surveillance system RF frequencies. As these activities 
proceed, FAA may remove one or more Mode-S terminal radars from 
operation, which would eliminate Mode-S TIS at that location.

II. Industry Discussion on Mode-S TIS Removal

    Using surveys and discussions with industry organizations, the FAA 
was able to obtain the necessary data required to understand the 
potential safety impacts from removing Mode-S TIS functionality from 
the existing terminal radars. FAA conducted surveys, such as the 
General Aviation/Part 135 Air Taxi Activity Survey, to produce a set of 
comprehensive data on part 91 and part 135 aircraft and their 
operations. The FAA reviewed data from survey reports for 2010, 2014, 
2016, 2018, and 2019, and discussed these reports with industry 
association experts. The data from these reports were utilized to study 
the relevant surveillance equipage for all types of aircraft: Fixed 
Wing Piston, Fixed Wing turboprop single and multi-engine, turbojet, 
and rotorcraft.
    Since 2018, the FAA has conducted industry briefings and 
discussions with major avionics manufacturing companies on the MSBRS 
program and the associated planned removal of Mode-S TIS from terminal 
radars. These discussions assisted in gathering pertinent information 
on equipage and gaining insight into potential concerns. Taking into 
consideration this information and the survey results, as well as the 
ADS-B In traffic services available to the cockpit via low-cost 
portable or integrated devices, the FAA determined that removal of 
Mode-S TIS had little to no significant adverse safety impacts on the 
GA Community.

III. Summary

    Based on industry engagement, FAA has determined that the removal 
of Mode-S TIS functionality will have little to no safety impact on the 
GA community.
    Removal of legacy terminal Mode-S radars may occur as part of other 
ongoing FAA activities to divest radars or which are being replaced 
with other modern cooperative surveillance systems. These activities 
are being pursued to lower FAA operating costs and/or reduce congestion 
on surveillance system RF frequencies.
    Aircraft operating within ADS-B mandated airspace, specified under 
14 CFR 91.225, have transitioned their avionics equipment to be 
compliant with the performance requirements of the regulation. If the 
ADS-B Out equipment is performing and configured properly, aircraft 
equipped with ADS-B In are capable of receiving ADS-R, ADS-SLR, and 
TIS-B services from the FAA ADS-B ground stations across the NAS. These 
low-cost ADS-B In avionics systems are widely available, and provide 
the GA community with a heightened situational awareness of the traffic 
around them which was not previously available using solely Mode-S TIS 
information. These services expand coverage and more than replace the 
information currently provided by Mode-S TIS.

    Issued in Washington, DC, on June 7, 2023.
Daniel S. Hicok,
Deputy Vice President (A), Program Management Organization, Air Traffic 
Organization.
[FR Doc. 2023-12607 Filed 6-22-23; 8:45 am]
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