Publications
Analysis of ground surveillance assets to support Global Hawk airspace access at Beale Air Force Base
August 10, 2007
Project Report
Published in:
Project Report ATC-335, MIT Lincoln Laboratory
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Summary
This study, performed from May 2006 to January 2007 by MIT Lincoln Laboratory, investigated the feasibility of providing ground-sensor-based traffic data directly to Global Hawk operators at Beale AFB. The system concept involves detecting and producing tracks for all cooperative (transponder-equipped) and non-cooperative aircraft from the surface to 18,000 ft MSL, extending from the Beale AFB Class C airspace cylinder northward to the China Military Operations Area (MOA). Data from multiple sensors can be fused together to create a comprehensive air surveillance picture, with the altitudes of non-cooperative targets estimated by fusing returns from all available sensor data. Such a capability, if accepted by the FAA, could mitigate the need for Temporary Flight Restrictions (TFR) to satisfy Certificate of Waiver or Authorization (COA) requirements. There are no existing specifications for ground-sensor-based Unmanned Aerial Systems (UAS) traffic avoidance procedures, nor is it yet known how precisely altitude needs to be estimated. It may be possible to avoid traffic laterally, in which case traffic altitude need not be known accurately. If, however, it is necessary to also avoid traffic vertically, then altitudes will need to be estimated to some (as yet undefined) level of accuracy.
Summary
This study, performed from May 2006 to January 2007 by MIT Lincoln Laboratory, investigated the feasibility of providing ground-sensor-based traffic data directly to Global Hawk operators at Beale AFB. The system concept involves detecting and producing tracks for all cooperative (transponder-equipped) and non-cooperative aircraft from the surface to 18,000 ft...
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Macroscopic workload model for estimating en route sector capacity
July 2, 2007
Conference Paper
Published in:
USA/Europe ATM Seminar, 2-5 July 2007.
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Summary
Under ideal weather conditions, each en route sector in an air traffic management (ATM) system has a certain maximum operational traffic density that its controller team can safely handle with nominal traffic flow. We call this the design capacity of the sector. Bad weather and altered flow often reduce sector capacity by increasing controller workload. We refer to sector capacity that is reduced by such conditions as dynamic capacity. When operational conditions cause workload to exceed the capability of a sector's controllers, air traffic managers can respond either by reducing demand or by increasing design capacity. Reducing demand can increase aircraft operating costs and impose delays. Increasing design capacity is usually accomplished by assigning more control resources to the airspace. This increases the cost of ATM. To ensure full utilization of the dynamic capacity and efficient use of the workforce, it is important to accurately characterize the capacity of each sector. Airspace designers often estimate sector capacity using microscopic workload simulations that model each task imposed by each aircraft. However, the complexities of those detailed models limit their real-time operational use, particularly in situations in which sector volumes or flow directions must adapt to changing conditions. To represent design capacity operationally in the United States, traffic flow managers define an acceptable peak traffic count for each sector based on practical experience. These subjective thresholds-while usable in decision-making-do not always reflect the complexity and geometry of the sectors, nor the direction of the traffic flow. We have developed a general macroscopic workload model to quantify the workload impact of traffic density, sector geometry, flow direction, and air-to-air conflict rates. This model provides an objective basis for estimating design capacity. Unlike simulation models, this analytical approach easily extrapolates to new conditions and allows parameter validation by fitting to observed sector traffic counts. The model quantifies coordination and conflict workload as well as observed relationships between sector volume and controller efficiency. The model can support real-time prediction of changes in design capacity when traffic is diverted from nominal routes. It can be used to estimate residual airspace capacity when weather partially blocks a sector. Its ability to identify dominant manual workload factors can also help define the benefits and effectiveness of alternative concepts for automating labor-intensive tasks.
Summary
Under ideal weather conditions, each en route sector in an air traffic management (ATM) system has a certain maximum operational traffic density that its controller team can safely handle with nominal traffic flow. We call this the design capacity of the sector. Bad weather and altered flow often reduce sector...
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Guidance material for Mode S-specific protocol application avionics
June 4, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-334
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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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Air traffic management decision support during convective weather
June 1, 2007
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 263-276.
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Flight delays caused by thunderstorms are a significant and growing problem for airlines and the flying public. Thunderstorms disrupt the structured, preplanned flight routing and control process that is used to handle dense air traffic streams in congested airspace. Today's coping strategies are developed by traffic flow management (TFM) specialists who interpret weather measurements and forecasts to develop delay and rerouting strategies. The effectiveness of these strategies is limited by the lack of quantitative models for the capacity impacts of thunderstorms, and by the difficulty of developing and executing timely response strategies during rapidly changing convective weather. In this article, we describe initial work to develop more effective response strategies. We first review insights gained during operational testing of a simple but highly effective Route Availability Planning Tool that can significantly reduce convective-weather induced departure delays at congested airports. We then discuss work to develop core technical capabilities and applications that address broader TFM problems, including en route congestion. Objective models for airspace capacity reductions caused by thunderstorms are discussed, as is an associated scheduling algorithm that exploits the capacity estimates to develop broad-area TFM strategies that minimize delay. We conclude by discussing candidate real-time applications and airspace system performance analysis that is enabled by our weather-capacity models and optimal scheduling algorithm.
Summary
Flight delays caused by thunderstorms are a significant and growing problem for airlines and the flying public. Thunderstorms disrupt the structured, preplanned flight routing and control process that is used to handle dense air traffic streams in congested airspace. Today's coping strategies are developed by traffic flow management (TFM) specialists...
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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.
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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Improving air traffic management group decision-making during severe convective weather
June 1, 2007
Conference Paper
Published in:
11th World Conf. on Transport Research, June 2007.
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Summary
There is an urgent need to enhance the efficiency of United States (U.S.) air traffic management (ATM) decision-making when convective weather occurs. Thunderstorm ATM decisions must be made under considerable time pressure with inadequate information (e.g., missing or ambiguous), high stakes, and poorly defined procedures. Often, multiple decisions are considered simultaneously; each requiring coordination amongst a heterogeneous set of decision-makers. Recent operational experience in the use of improved convective weather decision support systems in the Northeast quadrant of the U.S. is reviewed in the context of literature on individual and team decision-making in complex environments. Promising areas of research are identified.
Summary
There is an urgent need to enhance the efficiency of United States (U.S.) air traffic management (ATM) decision-making when convective weather occurs. Thunderstorm ATM decisions must be made under considerable time pressure with inadequate information (e.g., missing or ambiguous), high stakes, and poorly defined procedures. Often, multiple decisions are considered...
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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.
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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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Technical assessment of the impact of decommissioning the TDWR on terminal weather services
May 23, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-331
Summary
Details of a technical study that was part of a larger investigation assessing terminal weather services impacts of decommissioning the Terminal Doppler Weather Radar (TDWR) are presented. Effects on two key areas for safety and delay-reduction benefits are examined: low-altitude wind shear visibility and the Integrated Terminal Weather System (ITWS) Terminals Winds (TWINS) product. It is concluded that the information conted provided by the TDWR cannot, in general, be effectively replaced by other candidate radar systems such as the Airport Surveillance Radar (ASR-9) equipped with a Weather Systems Processor (WSP) or the Next Generation Weather Radar (NEXRAD).
Summary
Details of a technical study that was part of a larger investigation assessing terminal weather services impacts of decommissioning the Terminal Doppler Weather Radar (TDWR) are presented. Effects on two key areas for safety and delay-reduction benefits are examined: low-altitude wind shear visibility and the Integrated Terminal Weather System (ITWS)...
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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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Analysis of operational alternatives to the Terminal Doppler Weather Radar (TDWR)
February 26, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-332
Summary
Possible alternatives to the Terminal Doppler Weather Radar (TDWR) are assessed. We consider both the low altitude wind shear detection service provided by TDWR and its role in reducing weather-related airport delays through its input to the Integrated Terminal Weather System (ITWS). Airborne predictive wind shear (PWS) radars do not provide the broad area situational awareness needed to proactively reroute aircraft away from the affected runways. We considered in detail the alternative of using the ASR-9 Weather Systems Processor (WSP) and NEXRAD in lieu of TDWR. An objective metric for wind shear detection capability was calculated for each of these radars at all TDWR equipped airports. TDWR was uniformly superior by this metric, and at a number of the airports, the ASR-9/NEXRAD alternative scored so low as to raise questions whether it would be operationally acceptable. To assess airport weather delay reduction impact, we compared the accuracy of the high-benefit ITWS "Terminal Winds" product with and without TDWR input. Removal of the TDWR data would have increased the mean estimate error by a factor of 3 near the surface.
Summary
Possible alternatives to the Terminal Doppler Weather Radar (TDWR) are assessed. We consider both the low altitude wind shear detection service provided by TDWR and its role in reducing weather-related airport delays through its input to the Integrated Terminal Weather System (ITWS). Airborne predictive wind shear (PWS) radars do not...
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