Publications
Guidance material for Mode S-specific protocol application avionics
June 4, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-334
Summary
This ATC report presents guidance material for the use of "Ground-Initiated Comm. B" (GICB) register set contained in a Mode S transponder. The guidance material is intended to provide assistance for implementers of Mode S avionics installations. A common summary of the requirements and specifications for Mode S GICB transponder register data link applications is developed. While this ATC report focuses primarily on the "Elementary Surveillance" (ELS), "Enhanced Surveillance" (EHS), and "Automatic Dependent Surveillance-Broadcast" (ADS-B) applications, guidance information is also provided for general transponder configuration and architecture of other Mode S functions employing the GICB register set. Although the information contained in this ATC report is drawn from a number of approved national and international standards, it is not intended to replace or supersede those standards documents. In the event of a conflict or contradiction between this ATC report and any approved standards (see references 1 through 6), the approved standard takes precedence and the reader is encouraged to contact the authors of this document. Reference 4 is the most-recent and complete specification for the Mode S register contents. For ease of reference, the relevant Mode S register images have been duplicated in Appendix A of this report.
Summary
This ATC report presents guidance material for the use of "Ground-Initiated Comm. B" (GICB) register set contained in a Mode S transponder. The guidance material is intended to provide assistance for implementers of Mode S avionics installations. A common summary of the requirements and specifications for Mode S GICB transponder...
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Enhanced regional situational awareness
June 1, 2007
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 355-380.
Topic:
R&D area:
Summary
Airspace protection in the capital area is provided by an Integrated Air Defense System (IADS) created through the coordinated response of U.S. government and local law-enforcement agencies, including the Department of Defense, the Department of Homeland Security, the Federal Aviation Administration, and the Capitol Police. The IADS includes U.S. Coast Guard helicopters, fighter aircraft, and airborne early-warning aircraft cued by surveillance radars. Under Operation Noble Eagle, the response to a threat includes warning flares deployed from fighter aircraft and, ultimately, the use of surface and air-launched missiles. Selecting the appropriate response requires a means for rapidly assessing the aircraft threat. New and existing sensors must be simultaneously cued to the target of interest and integrated with existing sources of information to display a common-air-picture display to support the decision makers. This article describes the development of an Enhanced Regional Situation Awareness system, an integrated sensing and decision support system developed for the complex and busy airspace surrounding the National Capital Region.
Summary
Airspace protection in the capital area is provided by an Integrated Air Defense System (IADS) created through the coordinated response of U.S. government and local law-enforcement agencies, including the Department of Defense, the Department of Homeland Security, the Federal Aviation Administration, and the Capitol Police. The IADS includes U.S. Coast...
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The Traffic Alert and Collision Avoidance System
June 1, 2007
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 277-296.
Summary
The Traffic Alert and Collision Avoidance System (TCAS) has had extraordinary success in reducing the risk of mid-air collisions. Now mandated on all large transport aircraft, TCAS has been in operation for more than a decade and has prevented several catastrophic accidents. TCAS is a unique decision support system in the sense that it has been widely deployed (on more than 25,000 aircraft worldwide) and is continuously exposed to a high-tempo, complex air traffic system. TCAS is the product of carefully balancing and integrating sensor characteristics, tracker and aircraft dynamics, maneuver coordination, operational constraints, and human factors in time-critical situations. Missed or late threat detections can lead to collisions, and false alarms may cause pilots to lose trust in the system and ignore alerts, underscoring the need for a robust system design. Building on prior experience, Lincoln Laboratory recently examined potential improvements to the TCAS algorithms and monitored TCAS activity in the Boston area. Now the Laboratory is pursuing new collision avoidance technologies for unmanned aircraft.
Summary
The Traffic Alert and Collision Avoidance System (TCAS) has had extraordinary success in reducing the risk of mid-air collisions. Now mandated on all large transport aircraft, TCAS has been in operation for more than a decade and has prevented several catastrophic accidents. TCAS is a unique decision support system in...
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Surveillance improvement algorithms for Airport Surface Detection Equipment Model X (ASDE-X) at Dallas-Fort Worth Airport
April 20, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-333
Summary
Operational testing of the Runway Status Lights (RWSL) system at the Dallas-Fort Worth (DFW) airport has detected a number of cases where faults in the ASDE-X/DFW surveillance data have led to erroneous operation of the status lights. Among the surveillance problems noted during testing at DFW were: (a) false tracks, (b) track positional jumps to false locations, (c) Mode S track splits, (d) ATCRBS track splits, (e) invalid Mode C altitudes, (f) invalid track velocities, and (g) spurious Mode 3/a 06078 code tracks. The RWSL surveillance improvement algorithms package in this document is placed between the ASDE-X/DFW surveillance data source and the RESL safety logic. The surveillance improvement algorithms perform a variety of reasonableness and consistency checks on the input data and set validity flags and report status values for each input report which are then passed on to the RWSL safety logic. These flags and status values allow the RWSL to ignore erroneous reports and to avoid using questionable report components in the subsequent RWSL logic. This document illustrates the performance of the RWSL surveillance improvement algorithms package with examples from DFW analysis. It is shown that the RWSL surveillance improvement algorithms package substantially reduces the impact of the known ASDE-X/DFW surveillance anomalies on the performance of the RWSL safety logic. The RWSL surveillance improvement algorithms package may also host future algorithms necessary to mitigate further problems that might be detected in the surveillance data.
Summary
Operational testing of the Runway Status Lights (RWSL) system at the Dallas-Fort Worth (DFW) airport has detected a number of cases where faults in the ASDE-X/DFW surveillance data have led to erroneous operation of the status lights. Among the surveillance problems noted during testing at DFW were: (a) false tracks...
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Multifunction phased array radar: technical synopsis, cost implications, and operational capabilities
January 14, 2007
Conference Paper
Published in:
87th Annual American Meteorological Society Meeting, 14-18 January 2007.
Topic:
R&D area:
R&D group:
Summary
Current U.S. weather and aircraft surveillance radar networks vary in age from 10 to more than 40 years. Ongoing sustainment and upgrade programs can keep these operating in the near to mid term, but the responsible agencies (FAA, NWS and DoD/DHS) recognize that large-scale replacement activities must begin during the next decade. In addition, these agencies are re-evaluating their operational requirements for radar surveillance. FAA has announced that next generation air traffic control (ATC) will be based on Automatic Dependent Surveillance - Broadcast (ADS-B) (Scardina, 2002) rather than current primary and secondary radars. ADS-B, however, requires verification and back-up services which could be provided by retaining or replacing primary ATC radars.
Summary
Current U.S. weather and aircraft surveillance radar networks vary in age from 10 to more than 40 years. Ongoing sustainment and upgrade programs can keep these operating in the near to mid term, but the responsible agencies (FAA, NWS and DoD/DHS) recognize that large-scale replacement activities must begin during the...
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Required surveillance performance accuracy to support 3-mile and 5-mile separation in the National Airspace System
November 1, 2006
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-323
Summary
The Federal Aviation Administration is modernizing the Air Traffic Control system to improve flight efficiency, to increase capacity, to reduce flight delays, and to control operating costs as the demand for air travel continues to grow. Promising new surveillance technologies such as Automatic Dependent Surveillance Broadcast, (ADS-B), multisensor track fusion, and multifunction phased array radar offer the potential for increased efficiency in the National Airspace System (NAS). However, the introduction of these surveillance systems into the NAS is hampered because the FAA Order containing the surveillance requirements to support separation services assumes surveillance is provided by radar technology. The requirements are stated in terms that don't apply to new surveillance technologies. In order to take advantage of new surveillance technologies, the surveillance requirements to support separation services in the NAS must be articulated from a performance perspective that is not technology specific. This will allow the FAA to make the investment and performance trade-off analysis necessary to support the introduction of new surveillance technologies. [not complete]
Summary
The Federal Aviation Administration is modernizing the Air Traffic Control system to improve flight efficiency, to increase capacity, to reduce flight delays, and to control operating costs as the demand for air travel continues to grow. Promising new surveillance technologies such as Automatic Dependent Surveillance Broadcast, (ADS-B), multisensor track fusion...
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Improving the resolution advisory reversal logic of the traffic alert and collision avoidance system
October 15, 2006
Conference Paper
Published in:
25th IEEE/AIAA Digital Avionics Systems Conf., 15-18 October 2006, pp. 561-570.
Summary
The Traffic Alert and Collision Avoidance System (TCAS II) is the worldwide standard system for manned aircraft to avoid collisions with airborne transponder-equipped traffic. A safety vulnerability of the collision avoidance logic was reported by European analysts, who also proposed a change to correct it. The safety issue concerns limitations in the ability of TCAS to reverse the sense of a Resolution Advisory (RA) during an encounter. The issue was addressed by a team of experts1 in the Requirements Working Group (RWG) of RTCA Special Committee 147 [1]. This paper discusses the problem, the metrics and methods used in the analysis, and presents results that quantify the effectiveness of the proposed solution. Finally, recommendations are presented for implementing the change.
Summary
The Traffic Alert and Collision Avoidance System (TCAS II) is the worldwide standard system for manned aircraft to avoid collisions with airborne transponder-equipped traffic. A safety vulnerability of the collision avoidance logic was reported by European analysts, who also proposed a change to correct it. The safety issue concerns limitations...
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Operational evaluation of runway status lights
June 1, 2006
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 16, No. 1, June 2006, pp. 123-146.
Summary
To maintain safe separation of aircraft on the airport surface, air traffic controllers issue verbal clearances to pilots to sequence aircraft arrivals, departures, and runway crossings. Although controllers and pilots work together successfully most of the time, mistakes do occasionally happen, causing several hundred runway incursions a year and, less frequently, near misses and collisions in the United States. With this rate of incursions, it is imperative to have an independent warning system as a backup to the current system. Runway status lights, a system of automated, surveillance-driven stoplights, have been designed to provide this backup function. The lights are installed at runway-taxiway intersections and at departure points along the runways. They provide a clear signal to pilots crossing or departing from a runway, warning them of potential conflicts with traffic already on the runway. Existing FAA-installed radar surveillance is coupled with Lincoln Laboratory-developed algorithms to generate the light commands. To be compatible with operations at the busiest airports, the algorithms must drive the lights such that during normal operations pilots will almost never encounter a red light when it is safe to cross or depart from a runway. A minimal error rate must be maintained even in the face of inevitable imperfections in the surveillance system used to drive the safety logic. A prototype runway status light system has been designed at Lincoln Laboratory and installed at the Dallas/Fort Worth International Airport, where Laboratory personnel have worked with the FAA to complete an operational evaluation of the system, demonstrating the feasibility of runway status lights in the challenging, complex environment of one of the world's busiest airports.
Summary
To maintain safe separation of aircraft on the airport surface, air traffic controllers issue verbal clearances to pilots to sequence aircraft arrivals, departures, and runway crossings. Although controllers and pilots work together successfully most of the time, mistakes do occasionally happen, causing several hundred runway incursions a year and, less...
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Surveillance accuracy requirements in support of separation services
June 1, 2006
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 16, No. 1, June 2006, pp. 97-122.
Summary
The Federal Aviation Administration is modernizing the Air Traffic Control system to improve flight efficiency, to increase airspace capacity, to reduce flight delays, and to control operating costs as the demand for air travel continues to grow. Promising new surveillance technologies such as Automatic Dependent Surveillance Broadcast and multisensor track fusion offer the potential to augment the ground-based surveillance and controller-display systems by providing more timely and complete information about aircraft. The resulting improvement in surveillance accuracy may potentially allow the expanded use of the minimum safe-separation distance between aircraft. However, these new technologies cannot be introduced with today's radar-separation standards, because they assume surveillance will be provided only through radar technology. In this article, we review the background of aircraft surveillance and the establishment of radar separation standards. The required surveillance accuracy to safely support aircraft separation with National Airspace System technologies is then derived from currently widely used surveillance systems. We end with flight test validation of the derived results, which can be used to evaluate new technologies.
Summary
The Federal Aviation Administration is modernizing the Air Traffic Control system to improve flight efficiency, to increase airspace capacity, to reduce flight delays, and to control operating costs as the demand for air travel continues to grow. Promising new surveillance technologies such as Automatic Dependent Surveillance Broadcast and multisensor track...
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Evaluation of proposed changes to the ACAS modified tau calculation
May 1, 2006
Conference Paper
Published in:
Int. Civil Aviation Organization Aeronautical Surveillance Panel Working Group, 1 May 2006.
Summary
Modified tau is a parameter computed by ACAS to estimate the earliest time at which a collision could occur should an intruder aircraft accelerate toward the own aircraft. A concern with the modified tau calculation has been raised in a class of encounters where intruders are already close and converging slowly. In these problem cases, ACAS may induce a Near Mid-Air Collision by generating RAs with inappropriate timing or initial sense or failing to reverse sense when necessary. Performance in some problem encounters is greatly improved when using several proposed changes to the modified tau equations. These changes are outside CP112E, which focuses only on RA reversals. Although changes to modified tau resolve some problem encounters, aggregate risk-ratio results do not support implementing the existing proposals. There remains a concern about mid-air collision risk due to vulnerability in the existing modified tau equations, yet a robust solution to the problem has not been developed.
Summary
Modified tau is a parameter computed by ACAS to estimate the earliest time at which a collision could occur should an intruder aircraft accelerate toward the own aircraft. A concern with the modified tau calculation has been raised in a class of encounters where intruders are already close and converging...
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