Publications
Lincoln Laboratory Evaluation of TCAS II Logic Version 7 Appendices Volume II
December 13, 1999
Project Report
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MIT Lincoln Laboratory Report ATC-268,II
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Summary
Volume I described the analysis procedures and inputs. This volume presents tables and figures that were generated during the assessment to the TCAS Logic Performance.
Summary
Volume I described the analysis procedures and inputs. This volume presents tables and figures that were generated during the assessment to the TCAS Logic Performance.
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Lincoln Laboratory Evaluation of TCAS II Logic Version 7 Volume I
December 13, 1999
Project Report
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MIT Lincoln Laboratory Report ATC-268,I
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Summary
This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in the U.S. airspace. Version 7 is a major revision to the TCAS II logic consisting of more than 300 separately defined changes affecting all majot TCAS areas (surveillance, CAS logic and displays/aurals). Lincoln Laboratory Evaluated the logic by examining approximately two million simulated pairwise TCAS-TCAS encounters, derived from actual tracks recorded in U.S. airspace. The main goals of the evaluation were: (1) to study the performance of the new TCAS-TCAS coordinated reversal logic; (2) to detect and explain any areas of performance; (3) to examine the performance of the version 7 logic for the 30 Representative NMACs identified during the 6.04a logic evaluation; and (4) to understand the limitations of the logic by analyzing every version NMAC. Five Lincoln Laboratory analysis programs written for previous logic evaluation work were updated and new software was written to aid in the evaluation of TCAS-TCAS sense reversals. There were four phases of the evaluation corresponding to the above goals. For each phase the report gives an overview of the evaluation approach taken and a description of the results. An overall summary and perspective on the evolution of the TCAS II logic are given at the end of the report.
Summary
This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in...
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A comparative study of existing and proposed FAA and Eurocontrol CHIs for en route air traffic control
September 26, 1999
Conference Paper
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44th Annual Air Traffic Control Association Conf. Proc., 26-30 September 1999, pp. 22-26.
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In this paper we present a comparison of the Computer Human Interface (CHI) similarities and differences among the key Free Flight Phase 1 (FFP1) products for en route air traffic control (ATC) and air traffic control management (ATM) as well as some recent Eurocontrol-based CHI innovations. Our comparative study focuses on details of these disparate CHIs and the potential introduction of advanced graphical interactive features seen in the Eurocontrol CHI. Active US controllers who participated in Eurocontrol's Operational Display and Input Development (ODID) study have requested that the FAA develop an alternative CHI based on ODID and its successors such as the Denmark Sweden Interface (DSI). MIT Lincoln Laboratory has built a CHI Requirements Engineering Model (CREM) to support testing of an alternative ODID-like CHI that is feasible given the newly deployed Display System Replacement (DSR).
Summary
In this paper we present a comparison of the Computer Human Interface (CHI) similarities and differences among the key Free Flight Phase 1 (FFP1) products for en route air traffic control (ATC) and air traffic control management (ATM) as well as some recent Eurocontrol-based CHI innovations. Our comparative study focuses...
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Operational and spectrum tests for ATIDS at Dallas/Fort Worth Airport
September 20, 1999
Project Report
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MIT Lincoln Laboratory Report ATC-272
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Runway Incursion (RI) prevention is on the National Transportation Safety Board's (NTSB) list of "10 Most Wanted" safety improvements. Improved surveillance on the airport surface is an important ingredient in that it improves situational awareness and improves the accuracy of tracks used by automation algorithms. Towards this goal, the Runway Incursion Reduction Program (RIRP) has been developing the Airport Target Identification System (ATIDS). ATIDS is a prototype multilateration and Automatic Dependent Surveillance - Broadcast (ADS-B) system. It requires the enabling of existing transponders on the airport surface....The RIRP team, which includes the FAA Volpe National Transportation Systems Center, Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL) and Trios Associates, Inc., has conducted interferences tests at Dallas/Fort Worth Airport (DFW) to quantify the impact that ATIDS would have on that high-use environment. The tests included environmental 1040/1090 MHz measurements, ATCRBS false target investigations, and Mode S interrogation tests. This document reports the results of these tests. [Not complete].
Summary
Runway Incursion (RI) prevention is on the National Transportation Safety Board's (NTSB) list of "10 Most Wanted" safety improvements. Improved surveillance on the airport surface is an important ingredient in that it improves situational awareness and improves the accuracy of tracks used by automation algorithms. Towards this goal, the Runway...
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Rotating a weather map
June 1, 1999
Journal Article
Published in:
Dr. Dobb's J., Vol. 24, No. 6, June 1999, pp. 80-88.
Summary
Introduction: I was recently part of a project developing a system for aircraft pilots to access the national ground weather-radar database while in flight. This weather-radar graphical database is generated from the outputs of the FAA and National Weather Service network of radars covering the continental United States and is updated every five minutes. Each pixel in the database covers a square measuring two kilometers (about one nautical mile) on a side. The content of each data pixel is a measure of the radar reflectivity measured at that location - radar reflectivity is proportional to the water content in the atmosphere (the precipitation rate). This graphical database is available through several commercial vendors - it's what you see displayed on The Weather Channel or during typical TV weather reports. Our system, on the other hand, provides a low-speed digital datalink connection from an FAA ground computer to an avionics computer/display located in the aircraft cockpit.
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Introduction: I was recently part of a project developing a system for aircraft pilots to access the national ground weather-radar database while in flight. This weather-radar graphical database is generated from the outputs of the FAA and National Weather Service network of radars covering the continental United States and is...
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Lessons learned designing an alternative CHI for en route air traffic control
April 27, 1999
Conference Paper
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Controller Centered HMI, 27-29 April 1999.
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MIT Lincoln Laboratory is supporting the FAA-sponsored effort to design an operationally suitable Computer Human Interface (CHI) for the recently upgraded En Route Air Traffic Control Centers. All centers will soon receive new control consoles with state-of-the-art 20 square (2K by 2K resolution) color displays (currently operating in Seattle as of January 1999). The future CHI is being modeled on Eurocontrol's Operational Display and Input Development (ODID) CHI, as requested by active controllers in the US. The ODID-like CHI, with its minimal information display and color coded guidance, provides increased efficiency and productivity through employment of a modern graphical user interface. Lessons learned during the on-going design process, including research of look and feel issues in conjunction with data analysis from controller-in-the-loop testing of a prototype ODID-like CHI will be discussed. The Laboratory plans to model the alternative ODID-like CHI on the best of the European ODID, Denmark Sweden Interface (DSI) and EATCHIP CHI features, while cognizant of the FAA?s DSR capabilities and limitations to support an improved user interface. Human factors issues need resolution to provide a consistent look and feel across the Free Flight Phase 1 products and platforms, the Center TRACON Automation System (CTAS) and the User Request Evaluation Tool (URET). MIT Lincoln Laboratory has built a CHI Requirements Engineering Model (CREM) to support controller-in-the-loop testing of the ODID-like CHI, validate CHI requirements and determine applicable standards for the design of an integrated CHI. The CREM provides a means to assess various CHI alternatives and the capability to iterate options with controller teams to address user concerns. Lessons learned from the ODID-like CHI specification process will also be shared.
Summary
MIT Lincoln Laboratory is supporting the FAA-sponsored effort to design an operationally suitable Computer Human Interface (CHI) for the recently upgraded En Route Air Traffic Control Centers. All centers will soon receive new control consoles with state-of-the-art 20 square (2K by 2K resolution) color displays (currently operating in Seattle as...
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Development of improved TCAS II surveillance and interference limiting functions
January 1, 1999
Journal Article
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Air Traffic Control Q., Vol. 7, No. 1, 1999, pp. 19-46.
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This paper describes the development and validation of improved TCAS II intruder surveillance tracking and interference limiting algorithms. Improvements in interference limiting were prompted by the FAA Spectrum Management Office and by international aviation administrations in order to further reduce interference to ground-based air traffic control surveillance by TCAS II. Improvements in surveillance tracking were prompted by aircarrier pilot organizations in order to increase the level of traffic situational awareness offered by the TCAS II display. The new algorithms are included in a proposed new version of TCAS II MOPS DO-185A which is commonly referred to as Change 7.0. TCAS II change 7.0 units will be introduced into the US airspace beginning as early as 1999 as part of a program to implement improvements in both TCAS II surveillance and collision avoidance.
Summary
This paper describes the development and validation of improved TCAS II intruder surveillance tracking and interference limiting algorithms. Improvements in interference limiting were prompted by the FAA Spectrum Management Office and by international aviation administrations in order to further reduce interference to ground-based air traffic control surveillance by TCAS II...
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TCAS II use of ADS-B surveillance data through hybrid surveillance
January 1, 1999
Journal Article
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Air Traffic Control Q., Vol. 7, No. 2, 1999, pp. 109-121.
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This paper describes a technique that enables TCAS II to use passive surveillance data obtained via extended squitter, an implementation of automatic dependent surveillance broadcast (ADS-B). The technique, known as hybrid surveillance, is based upon the use of TCAS active surveillance to perform validation of the reported ADS-B position at track acquisition. Aircraft that pass initial validation are maintained on passive surveillance until they become a near threat. At that time, TCAS begins regular active surveillance and thus uses its current surveillance techniques for traffic and resolution advisories. In this way, TCAS is able to use passive extended squitter data while retaining its role as an independent monitor. Simulation results show that the use of passive information for non-threatening aircraft results in a significant decrease in TCAS interrogation rate. This enables TCAS to delay or avoid the range reduction that is now required in order for TCAS to remain within its interference budget in high traffic density airspace. Maintaining TCAS operating range in high density air-space enhances TCAS ability to support situational awareness for the flight crew.
Summary
This paper describes a technique that enables TCAS II to use passive surveillance data obtained via extended squitter, an implementation of automatic dependent surveillance broadcast (ADS-B). The technique, known as hybrid surveillance, is based upon the use of TCAS active surveillance to perform validation of the reported ADS-B position at...
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Techniques for improved reception of 1090 MHz ADS-B signals
October 31, 1998
Conference Paper
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17th DASC: Proc. of the 17th. Digital Avionics Systems Conf., 31 October - 7 November 1998, Vol. 2, pp. G25-1 - G25-9.
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The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters and the associated position and status. Squitter reception includes the detection of the Mode S 1090 MHz waveform preamble, declaration of the bit and confidence values, error detection, and (if necessary) error correction. The current techniques for squitter reception are based upon methods developed for use in Mode S narrow-beam interrogators and for ACAS. In both of these applications, the rate of Mode NC fruit that is stronger than the Mode S waveform is relatively low, nominally less than 4,000 fruit per second. Extended squitter applications now include long range (up to 100 nmi) air-air surveillance in support of free flight. This type of surveillance is sometimes referred to as Cockpit Display of Traffic Information (CDTI). In high density environments, it is possible to operate with fruit rates of 40,000 fruit per second and higher. Operation of extended squitter in very high ModeNC fruit environments has led to the need to re-evaluate squitter reception techniques to determine if improved performance is achievable. The purpose of this paper is to provide a summary of work in progress to investigate improved squitter reception techniques. Elements of improved squitter reception being investigated include (1) the use of amplitude to improve bit and confidence declaration accuracy, (2) more capable error correction algorithms, and (3) more selective preamble detection approaches.
Summary
The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters...
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Multilateration on Mode S and ATCRBS signals at Atlanta's Hartsfield Airport
January 8, 1998
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-260
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The ATC community is seeking a way to obtain aircraft ID and improved surveillance on the airport movement area. Surface radars provide good surveillance data, but do not provide ID, may not cover the whole movement area, and suffer from false reflection targets and performance degradations in rain. This report describes an evolutionary technique employing multilateration, TCAS technology, and existing ATCBI transponders to provide the desired surface surveillance information. Five multilateration receiver/transmitters (RTs) based on TCAS units, and a central multilateration computer processor were procured and installed on the highest available buildings on the perimeter of the north side of Atlanta's Hartsfield airport. The resulting coverage was such that there was a 93% probability that a multilateration position would be computed on a given Mode S short squitter emitted from a a target at a randomly selected position on the movement area. Multilateration was performed on ATCRBS targets using replies elicited by whisper shout methods originally developed for TCAS. Measurements showed that whisper shout was successful in degarbling targets that were in close proximity on the movement area. The probability of obtaining an ATCRBS multilateration position in a given one second interval depended on the number of whisper shout interrogations transmitted. The equipment required over 10 interrogations per target per second to obtain per second multilateration update rates on two typical targets of 58% and 83% respectively. This less than anticipated performance was primarily due to the inefficient whisper shout interrogation technique that was used in the test equipment. This can be corrected in next generation equipment. The multilateration accuracy was about 20 feet one sigma, as anticipated from theoretical considerations and previous experience with other equipment. By combining the multilateration data with ASDE data and tracking the results, it would be possible to obtain track reliabilities on the airport surface similar to that obtained elsewhere in the ATC system but update rates of 1Hz as required for surface surveillance and control purposes. The RTs were also capable of receiving Mode S long squitters containing GPS position information. The probability of at least one of the 5RTs receiving a given long squitter was essentially 100% on the movement area.
Summary
The ATC community is seeking a way to obtain aircraft ID and improved surveillance on the airport movement area. Surface radars provide good surveillance data, but do not provide ID, may not cover the whole movement area, and suffer from false reflection targets and performance degradations in rain. This report...
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