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Quantifying convective delay reduction benefits for weather/ATM systems
June 27, 2005
Conference Paper
Published in:
USA/Europe Air Traffic Management Seminar, 27-30 June 2005.
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Summary
This paper investigates methods for quantifying convective weather delay reduction benefits for weather/ATM systems and recommends approaches for future assessments. This topic is particularly important at this time because: 1. Convective weather delays continue to be a dominant factor in the overall National Airspace System (NAS) delays, and 2. Benefits quantification and NAS performance assessment have become very important in an era of significant government and airline budget constraints for civil aviation investments. Quantifying convective weather delay benefits for ATM systems has proven to be quite difficult since the delays arise from complicated, highly variable, poorly understood interactions between convective weather and a very complex aviation system. In this paper, we consider key aspects of convective weather disruptions of the aviation system, how the weather severity can be characterized, and discuss practical experience with benefits quantification by a variety of approaches. The paper concludes with recommendations for a methodology to be used in future convective weather delay reduction quantification studies.
Summary
This paper investigates methods for quantifying convective weather delay reduction benefits for weather/ATM systems and recommends approaches for future assessments. This topic is particularly important at this time because: 1. Convective weather delays continue to be a dominant factor in the overall National Airspace System (NAS) delays, and 2. Benefits...
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Safety analysis for advanced separation concepts
June 27, 2005
Conference Paper
Published in:
USA/Europe Air Traffic Management Seminar, 27-30 June 2005.
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Aviation planners have called for increasing the capacity of the air transportation system by factors of two or three over the next 20 years. The inherent spatial capacity of en route airspace appears able to accommodate such traffic densities. But controller workload presents a formidable obstacle to achieving such goals. New approaches to providing separation assurance are being investigated to overcome workload limitations and allow airspace capacity to be fully utilized. One approach is to employ computer automation as the basis for separation-assurance task. This would permit traffic densities that exceed the level at which human cognition and decision-making can assure separation. One of the challenges that must be faced involves the ability of such highly automated systems to maintain safety in the presence of inevitable subsystem faults, including the complete failure of the supporting computer system. Traffic density and flow complexity will make it impossible for human service providers to safely reinitiate manual control in the event of computer failure, so the automated system must have inherent fail-soft features. This paper presents a preliminary analysis of the ability of a highly automated separation assurance system to tolerate general types of faults such as nonconformance and computer outages. Safety-related design features are defined using the Advanced Airspace Concept (AAC) as the base architecture. Special attention is given to the impact of a severe failure in which all computer support is terminated within a defined region. The growth and decay of risk during an outage is evaluated using fault tree methods that integrate risk over time. It is shown that when a conflict free plan covers the region of the outage, this plan can be used to safely transition aircraft to regions where service can still be provided.
Summary
Aviation planners have called for increasing the capacity of the air transportation system by factors of two or three over the next 20 years. The inherent spatial capacity of en route airspace appears able to accommodate such traffic densities. But controller workload presents a formidable obstacle to achieving such goals...
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An analysis of wake vortex lidar measurements at LaGuardia Airport
November 30, 2004
Project Report
Published in:
Project Report ATC-318, MIT Lincoln Laboratory
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The majority of research into the wake vortex hazard has concentrated on the in-trail encounter scenario for arrivals. At LaGuardia Airport, wake vortex spacings are applied to arrivals on runway 22 following a heavy departure on the intersecting runway 31, resulting in delay and increased workload for controllers. Previous analysis of this problem led to a recommendation for a measurement campaign to collect data on the behavior of wake vortices generated by departing heavy aircraft. In April of 2004, MIT Lincoln Laboratory deployed its wake vortex lidar system to measure such wakes at LaGuardia. Additionally, wind speed and turbulence data were collected with the hope of correlating wake behavior with the local atmospheric conditions. Analysis of the lidar data indicates that the system was able to acquire and track vortices from departures, a task not proven prior to this deployment. Further, vortices were seen to transport toward the threshold of runway 22, verifying an assumption based on analysis of the winds that wake transport is not a solution in this case. The quantity and type of data collected were insufficient to formulate a clear relationship between atmospheric turbulence and vortex decay. However, it may be possible to develop such a model by exploiting the data gathered during previous lidar deployments.
Summary
The majority of research into the wake vortex hazard has concentrated on the in-trail encounter scenario for arrivals. At LaGuardia Airport, wake vortex spacings are applied to arrivals on runway 22 following a heavy departure on the intersecting runway 31, resulting in delay and increased workload for controllers. Previous analysis...
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Remotely piloted vehicles in civil airspace: requirements and analysis methods for the traffic alert and collision avoidance system (TCAS) and see-and-avoid systems
October 24, 2004
Conference Paper
Published in:
Proc. of the 23rd Digital Avionics Systems Conf., DASC, Vol. 2, 24-28 October 2004, pp. 12.D.1-1 - 12.D.1.14.
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The integration of Remotely Piloted Vehicles (RF'Vs) into civil airspace will require new methods of ensuring aircraft separation. This paper discusses issues affecting requirements for RPV traffic avoidance systems and for performing the safety evaluations that will be necessary to certify such systems. The paper outlines current ways in which traffic avoidance is assured depending on the type of airspace and type of traffic that is encountered. Alternative methods for RPVs to perform traffic avoidance are discussed, including the potential use of new see-and-avoid sensors or the Traffic Alert and Collision Avoidance System (TCAS). Finally, the paper outlines an established safety evaluation process that can be adapted to assure regulatory authorities that RPVs meet level of safety requirements.
Summary
The integration of Remotely Piloted Vehicles (RF'Vs) into civil airspace will require new methods of ensuring aircraft separation. This paper discusses issues affecting requirements for RPV traffic avoidance systems and for performing the safety evaluations that will be necessary to certify such systems. The paper outlines current ways in which...
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Improving convective weather operations in highly congested airspace with the Corridor Integrated Weather System (CIWS)
October 4, 2004
Conference Paper
Published in:
11th Conf. on Aviation, Range and Aerospace Meteorology, 4-8 October 2004.
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Summary
Reducing thunderstorm-related air traffic delays in congested airspace has become a major objective of the FAA, especially given the recent growth in convective delays. In 2000 and 2001, the key new initiative for reducing these convective weather delays was "strategic" traffic flow management (TFM). Users were given 2-, 4-, and 6-hour collaborative convective weather forecasts, and collaborative traffic routing plans were established via telecons attended by Air Traffic Control (ATC) and airline traffic managers. This "strategic" approach led to difficulties during a large fraction of the weather events because it was not possible to generate forecasts of convective weather at time horizons between 2 and 6 hours that were accurate enough to assess impacts on routes and capacity, and thereby accomplish effective TFM. During convective weather events, traffic managers tend to focus on tactical TFM [Huberdeau, 2004], yet they had relatively inaccurate current weather information and tactical forecasts. The Corridor Integrated Weather System (CIWS) demonstration began in 2001. The objectives of the demonstration are to provide improved tactical air traffic management (ATM) decision support, via improved real time 3D products and accurate short-term convective weather forecasts, and to determine if this support is an operationally useful complement to "strategic" TFM. The current focus of the CIWS initiative is the highly congested airspace containing the Great Lakes and Northeast corridors, since that region offers the greatest potential for delay reduction benefits. In this paper, we describe the current status of CIWS, including initial operational results of Air Traffic Control (ATC) and airline use of the CIWS weather products. We begin with some CIWS background, describing the motivation for the program, the role of CIWS products in the overall convective weather planning process, and the functional domains in which CIWS products can provide operationally significant benefits. We then review the current CIWS capabilities, spatial coverage, sensors used, products, operational users, and integration with ATM systems. Next the detailed CIWS operational benefits study carried out in 2003 is summarized. Finally, we discuss the FAA plans for CIWS and near term enhancements to the system.
Summary
Reducing thunderstorm-related air traffic delays in congested airspace has become a major objective of the FAA, especially given the recent growth in convective delays. In 2000 and 2001, the key new initiative for reducing these convective weather delays was "strategic" traffic flow management (TFM). Users were given 2-, 4-, and...
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Tactical 0-2 hour convective weather forecasts for FAA
October 4, 2004
Conference Paper
Published in:
11th Conf. on Aviation, Range and Aerospace Meteorology, 4-8 October 2004.
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Major airlines and FAA Traffic Flow Managers alike would prefer to plan their flight routes around convective weather and thereby avoid the tactical maneuvering that results when unforecasted thunderstorms occur. Strategic planning takes place daily and 2-6 hr forecasts are utilized, but these early plans remain unaltered in only the most predictable of convective weather scenarios. More typically, the ATC System Command Center and the Air Route Traffic Control Centers together with airline dispatchers will help flights to utilize jet routes that remain available within regions of convection, or facilitate major reroutes around convection, according to the available "playbook" routes. For this tactical routing in the presence of convective weather to work, both a precise and timely shared picture of current weather is required as well as an accurate, reliable short term (0-2 hr) forecast. This is crucial to containing the system-wide and airport-specific delays that are so prevalent in the summer months (Figure 1), especially as traffic demands approach full capacity at the pacing airports. This paper describes the Tactical 0-2 hr Convective Weather Forecast (CWF) algorithm developed by the MIT Lincoln Laboratory for the FAA, principally sponsored by the Aviation Weather Research Program (AWRP). This CWF technology is currently being utilized in both the Integrated Terminal Weather System (ITWS; Wolfson et al., 2004) and the Corridor Integrated Weather System (CIWS; Evans et al., 2004) proof-of-concept demonstrations. Some of this technology is also being utilized in the National Convective Weather Forecast from the Aviation Weather Center (Megenhardt, 2004), the NCAR Autonowcaster (Saxen et al., 2004), and in various private-vendor forecast systems.
Summary
Major airlines and FAA Traffic Flow Managers alike would prefer to plan their flight routes around convective weather and thereby avoid the tactical maneuvering that results when unforecasted thunderstorms occur. Strategic planning takes place daily and 2-6 hr forecasts are utilized, but these early plans remain unaltered in only the...
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Adaptive doppler filtering applied to modern air traffic control radars
April 26, 2004
Conference Paper
Published in:
Proc. of the IEEE 2004 Radar Conf., 26-29 April 2004, pp. 242-248.
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This paper presents an analysis of the Doppler processing technology currently in use in the nation's terminal airport surveillance radars, and examines possibilities for performance improvement, particularly in the presence of moving clutter. The research focuses on five- and eight-pulse waveform methodologies and their respective detection capabilities given clearly defined rain clutter scenarios. Performance with fixed coefficient filters similar to those used in the existing radars is calculated, followed by performance using an adaptive Doppler filtering technique. Performance is quantified in terms of signal-to-interference ratio at the output of the Doppler filters and resultant probability of detection given a specified probability of false alarm. The results will show that a substantial improvement in detection in the vicinity of rain clutter is realized for both the five- and eight-pulse waveforms when using the adaptive coefficient Doppler filters as compared to the performance observed with the fixed coefficient filters. For constant filter weights, the eight-pulse Doppler filters give significantly better performance in most diverse rain clutter than the five-pulse Doppler filters.
Summary
This paper presents an analysis of the Doppler processing technology currently in use in the nation's terminal airport surveillance radars, and examines possibilities for performance improvement, particularly in the presence of moving clutter. The research focuses on five- and eight-pulse waveform methodologies and their respective detection capabilities given clearly defined...
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An examination of wind shear alert integration at the Dallas/Ft. Worth International Airport (DFW)
August 20, 2003
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-309
Summary
The Dallas / Fort Worth International Airport (DFW) is one of the four demonstration system sites for the Integrated Terminal Weather System (ITWS). One of the primary benefits of the ITWS is a suite of algorithms that utilize data from the Terminal Doppler Weather Radar (TDWR) to generate wind shear alerts. DFW also benefits from a Network Expansion of the Low-Level Wind Shear Advisory System (LLWAS-NE). The LLWAS-NE generated alerts are integrated with the radar-based alerts in ITWS to provide Air Traffic Control (ATC) with a comprehensive set of alert information. This study examines the integrated DFW wind shear alerts with emphasis on circumstances in which the detection performance of the TDWR-based wind shear algorithms was poor. Specific detection problems occur in the following situations: when wind shear events over the airport are aligned along a radial to the TDWR, during "non-traditional" wind shear events, when severe signal attenuation occurs during heavy precipitation over the TDWR radar site, and because of excessive TDWR clutter-residue editing over the airport. In all of the cases examined, the LLWAS-NE issued alerts to ATC that would have otherwise gone unreported.
Summary
The Dallas / Fort Worth International Airport (DFW) is one of the four demonstration system sites for the Integrated Terminal Weather System (ITWS). One of the primary benefits of the ITWS is a suite of algorithms that utilize data from the Terminal Doppler Weather Radar (TDWR) to generate wind shear...
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ADS-B Airborne Measurements in Frankfurt
October 27, 2002
Conference Paper
Published in:
21st AIAA/IEEE Digital Avionics Systems Conf., 27-31 October 2002, pp. 3.A.3-1 - 3.A.3-11.
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Automatic Dependent Surveillance-Broadcast (ADS-B) was the subject of airborne testing in Frankfurt, Germany in May 2000. ADS-B is a system in which latitude-longitude information is broadcast regularly by aircraft, so that receivers on the ground and in other aircraft can determine the presence and accurate locations of the transmitting aircraft. In addition to the latitude and longitude, ADS-B transmissions include altitude, velocity, aircraft address, and a number of other items of optional information. The tests in Germany were aimed at assessing the performance of Mode S Extended Squitter, which is one of several possible implementations of ADS-B. Extended Squitter uses a conventional Mode S signal format, specifically the 112-bit reply format at 1090 MHz, currently being used operationally for air-to-ground communications and air-to-air coordination in TCAS (Traffic Alert and Collision Avoidance System).
Summary
Automatic Dependent Surveillance-Broadcast (ADS-B) was the subject of airborne testing in Frankfurt, Germany in May 2000. ADS-B is a system in which latitude-longitude information is broadcast regularly by aircraft, so that receivers on the ground and in other aircraft can determine the presence and accurate locations of the transmitting aircraft...
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Analysis and comparison of separation measurement errors in single sensor and multiple radar mosiac display terminal environments
October 21, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-306
Summary
This paper presents an analyis to estimate and characterize the errors in the measured separation distance between aircraft that are displayed on a radar screen to a controller in a single sensor terminal environment compared to a multiple radar mosiac terminal environment. The error in measured or displayed separation is the difference between the true separation or distance between aircraft in the air and the separation displayed to a controller on a radar screen. In order to eliminate as many variables as possible and to concentrate specifically on the differences between displayed separation errors in the two environments, for the purposes of this analysis, only full operation Mode S secondary beacon surveillance characteristics are considered. A summary of the Mode S secondary radar error sources and characteristics used to model the resultant errors in measured separation between aircraft in single and multi-radar terminal environments is presented. The analysis for average separation errors show that the performance of radars in providing separation services degrades with range. The analysis also shows that when using independent radars in a mosiac display, separation errors will increase, on average, compared to the performance when providing separation with a single radar. The data presented in the section on average separation errors is summarized by plotting the standard deviation of the separation error as a function of range for the single radar case and for the independent mosiac display case. The sections on typical and specific errors in separation measurements illustrate that the separation measurement errors are highly dependent on the geometry of the aircraft and radars. Applying average results to specific geometries can lead to counter intuitive results is illustrated in an example case presented in analysis.
Summary
This paper presents an analyis to estimate and characterize the errors in the measured separation distance between aircraft that are displayed on a radar screen to a controller in a single sensor terminal environment compared to a multiple radar mosiac terminal environment. The error in measured or displayed separation is...
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