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ATCBI-6 Long-Range Beacon Radar Set - A Long-Range Air Traffic Control Beacon Interrogator Model 6 (ATCBI-6) radar set built by the Raytheon Company.

The Federal Aviation Administration (FAA) selected the Raytheon Company's ATCBI-6 beacon system on 4 Aug 1998 to replace the aging ATCBI-3, ATCBI-4, and ATCBI-5 beacon sets in the en-route Air Traffic Control System. The FAA awarded a contract potentially worth US$180 million to manufacture and install up to 152 ATCBI-6 systems. DT&E was completed in September 1999, and OT&E began in October 1999. Key site commissioning took place in April 2000.

In August 2002, the FAA commissioned into service the first production ATCBI-6 system at Tinker AFB, Oklahoma. The last ATCBI-6 system was commissioned in FY 2013,


The ATCBI-6 Beacon, with Mode S selective addressing capability, obtains information from en-route aircraft, including identification, altitude, airspeed, and direction. The ATCBI-6 system integrates with existing primary surveillance radars (ARSR-4, CARSR, and FPS-117) operated by the FAA and the Department of Defense (DoD). The ATCBI-6M version supports the Mode 4 operation and appears to be deployed with all the ARSR-4 CONUS Sets (42). The regular ATCBI-6 is deployed at CARSR sites.

The ATCBI-6 includes most of the functionality of a traditional Mode S interrogator but it doesn’t have the data link feature, causing some to call it "Mode S lite." It does not appear that the first 23 FAA long range radar sites to be equipped with the initial Mode S equipment have been changed to use the ATCBI-6.

The ATCBI-6 provides four commonly used modes, mode 1, mode 2, mode 3/A, and mode C. Mode 1 is used to ID military targets. Mode 2 is used to identify military aircraft missions. Mode 3/A is used to identify each aircraft in the radar's coverage area. Mode C is used to report an aircraft's altitude. Mode 3/A is designated as the common military/civil mode for air traffic control use. The distribution of Mode 3/A codes is governed by The National Beacon Code Allocation Plan (NBCAP) laid out in FAA orders. Mode S is a discrete selective interrogation that ignores interrogations not addressed with a unique identity code.

Mode 4 is not considered part of the ATCRBS system, but it uses the same transmit and receiver hardware. Mode 4 is used by military aircraft for the Identification Friend or Foe (IFF) system.

Mark XII Mode 4 technology is the current military standard for U.S. and NATO countries. In 1995 the US Joint Chiefs of Staff ordered the development of a new Mode 5 to replace the current Mode 4 system. The transition to the new Mark XIIA Mode 5 equipment is now in process and will require a major effort for the U.S. military over the next 10-15 years.

ATCBI-6 Sustainment Program

From the FY 2020 President’s Budget Submission to Congress:

The ATCBI-6 is a Monopulse Secondary Surveillance Radar (MSSR) with selective interrogation capability that significantly improves the accuracy of aircraft position and altitude data provided to ATC automation systems. The ATCBI-6 program commissioned the first system in FY 2002 and the last system in FY 2013. This technology refresh activity will determine the retrofit requirement for the 132 operational and seven support ATCBI-6 systems, keeping the systems operational until SENSR deployment. For FY 2020, $3.0 million is requested to support the Final Investment Decision (FID). This includes Contractor Support and Benefit Analysis, Program Management, Logistics, and Sustainability Study, System Engineering and Second Level Engineering Analysis, Shortfall Analysis, the development of an Independent Government Cost Estimate, Business Case Analysis Report, and the Initial Implementation Strategy and Planning Document. FID is planned for December 2021.


The FAA conducts in-house training on the ATCBI-6/6M beacon system in Course FAA40675 titled "ATCBI-6/6M EHOT". The course is 120 hours long with 16 hours of lecture and 88 hours of lab work. Class size is 4 persons and they plan to conduct 10 classes in calendar year 2019 at their training academy. See FAA En-Route Radar Site Maintenance Training.

ATCBI-6 Beacon Radar

ATCBI-6 Beacon Radar
Element Value Notes
Nomenclature ATCBI-6
Origins ATCBI-3
Variants ATCBI-6M
Manufacturer Raytheon
Type Beacon
Number in NAS 87~ ATCBI-6
Target Capacity 1,400
IEEE Band L-Band
Transmit Frequency 1,030 MHz
Receive Frequency 1,090 MHz
Antenna MonoPulse
Waveform ATCBI-6 ATCRBS/Mode S
Range 225 mi (362 km) Long-Range
Altitude 100k Feet
Introduced First production Model Commissioned August 2002 at Tinker AFB

Early View of ATCBI-6.

See Also:



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