Publications
Model estimates of traffic reduction in storm impacted en route airspace
September 18, 2007
Conference Paper
Published in:
7th AIAA Aviation Technology, Integration, and Operations (ATIO) Conf., 18-20 September 2007.
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Summary
An understanding of convective weather impacts on en route airspace capacity is a first step toward development of predictive tools to support both tactical and strategic routing decisions in storm-impacted airspace. This study presents a model for traffic reductions in en route sectors that result from convective weather impacts. A model to predict the impact of convective weather on en route traffic, Traffic Normalized Fractional Route Availability (TNFRA), combines Weather Avoidance Fields (WAF) from the Convective Weather Avoidance Model (CWAM) with a model for route usage in air traffic control (ATC) sectors. The model estimates the number of flights that will be able to pass through convective weather in a given sector. Results show that TNFRA provides a relatively unbiased estimate of sector traffic when compared to actual operations during high impact - convective weather events.
Summary
An understanding of convective weather impacts on en route airspace capacity is a first step toward development of predictive tools to support both tactical and strategic routing decisions in storm-impacted airspace. This study presents a model for traffic reductions in en route sectors that result from convective weather impacts. A...
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Evaluation of potential NEXRAD dual polarization products
September 4, 2007
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-336
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Summary
The NEXRAD program will begin fielding a dual polarization capability in 2009. Three additional base data parameters and two additional derived parameters from the dual polarization capability will be produced to complement the traditional three radar moments. The initial use of the added data is to provide a dual-polarization-based quantitative precipitation estimate (QPE) algorithm. Other NEXRAD algorithms will have access to the new dual polarization parameters as well as the derived products. The National Severe Storms Laboratory coordinated a dual polarization product evaluation to solicit NEXRAD agency participant feedback regarding potential dual polarization products. The evaluation consisted of analyzing dual polarization data from seven weather cases. MIT Lincoln Laboratory participated in the evaluation. The evaluation opportunity was used to have early access to prototypical dual polarization data to consider the potential benefit to FAA weather systems. This report introduces the new dual polarization pararmeters, presents some of the relevant weather cases, and provides recommendations regarding use of the dual polarization parameters.
Summary
The NEXRAD program will begin fielding a dual polarization capability in 2009. Three additional base data parameters and two additional derived parameters from the dual polarization capability will be produced to complement the traditional three radar moments. The initial use of the added data is to provide a dual-polarization-based quantitative...
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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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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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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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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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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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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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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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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.
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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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An automated visibility detection algorithm utilizing camera imagery
January 14, 2007
Conference Paper
Published in:
87Th AMS Annual Meeting, 14-18 January 2007.
Summary
The Federal Highway Administration (FHWA) has had a focused program to improve the integration of weather decision support systems into surface transportation operations since 1999. Clarus (Latin for clear) is the FHWA's most recent surface transportation weather initiative. The Clarus concept is to develop and demonstrate an integrated surface transportation weather observing, forecasting and data management system (Pisano, 2006a). As part of this effort, the FHWA is also promoting research into methods for applying new and existing sensor or probe data. These efforts include utilizing new in-vehicle sensor data that will be part of the vehicle infrastructure initiative (VII) (Pisano, 2006b), and finding innovative ways to use existing camera imagery. MIT Lincoln Laboratory (MIT/LL) was tasked to evaluate the usefulness of camera imagery for sensing ambient and road weather conditions and the feasibility for creating a portable visibility estimation algorithm. This paper gives a general background on the current utilization of camera imagery, including past and ongoing research of automated weather/condition algorithms. This is followed by a description of the MIT/LL camera test site, the analyses performed and the resultant prototype visibility estimation algorithm. In addition, the paper details application of the prototype algorithm to existing state DOT cameras in Utah. The final section discusses the future possibilities of camera-based weather and road condition algorithms.
Summary
The Federal Highway Administration (FHWA) has had a focused program to improve the integration of weather decision support systems into surface transportation operations since 1999. Clarus (Latin for clear) is the FHWA's most recent surface transportation weather initiative. The Clarus concept is to develop and demonstrate an integrated surface transportation...
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