Publications
Analysis of the Integrated Terminal Weather System (ITWS) 5-nm product suite
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp.137-140.
Summary
Currently, the prototype Integrated Terminal Weather System (ITWS) displays six-level precipitation data generated from the Airport Surveillance Radar (ASR-9) and the Next Generation Weather Radar (NEXRAD). The ASR-9 data are updated every 30 seconds and provide a 0.5 nm spatial resolution to a distance of 60 nm (Weber, 1986). Since the ASR-9 is a fan beam radar, the data represent the average precipitation within the vertical column. As reported by Isaminger, et al., (1999), this sensor can significantly underestimate the precipitation intensity and areal coverage due to precipitation processing limitations and hardware failures. In particular, storms located near the sensor can be underestimated or missed entirely (Crow& et al., 1999). The NEXRAD data are updated every 5-6 minutes with a spatial resolution of 0.5 nm (2.2 nm) and a coverage region of 100 nm (200 nm). The maximum reflectivity value in the vertical column at each grid point is used to create the product. This sensor can overestimate the precipitation intensity near the surface due to bright band contamination and the composite technique (Crowe and Miller, 1999). The update rate can also become an issue if the storms are moving rapidly or developing quickly. In order to confront these issues, the specified ITWS product suite will include six-level precipitation derived from the Terminal Doppler Weather Radar (TDWR). The data from this sensor will be depicted in a high-resolution window (5-nm) around the airport. The TDWR one-minute update rate will provide timely information on rapidly moving or developing storm cells. In many regards, the data will be complimentary to that provided by the ASR-9 and NEXRAD. In others, the weather levels could vary significantly. This report will focus on a discussion of the 5-nm product capabilities and limitations based on an analysis of data collected in Memphis (MEM) and New York City (NYC). A discussion of key product enhancements will serve to illustrate the modifications required to improve this product suite. Finally, a list of recommendations will be presented to assist in product development.
Summary
Currently, the prototype Integrated Terminal Weather System (ITWS) displays six-level precipitation data generated from the Airport Surveillance Radar (ASR-9) and the Next Generation Weather Radar (NEXRAD). The ASR-9 data are updated every 30 seconds and provide a 0.5 nm spatial resolution to a distance of 60 nm (Weber, 1986). Since...
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Developing a mosiacked gust front detection algorithm for TRACONS with multiple TDWRS
September 11, 2000
Conference Paper
Published in:
Proc. Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 494-498.
Summary
Gust front detection is an important Initial Operational Capability (IOC) of the Integrated Terminal Weather System (ITWS). The Machine Intelligent Gust Front Algorithm (MIGFA) being deployed for ITWS uses multi-dimensional, knowledge-based signal processing techniques to detect and track gust fronts in Terminal Doppler Weather Radar (TDWR) data. Versions of MIGFA have also been developed for the ASR-9 Weather Systems Processor (WSP) and NEXRAD, and within the past year MIGFA was installed as the primary gust front detection algorithm for operational TDWRs throughout the United States. (Not complete.)
Summary
Gust front detection is an important Initial Operational Capability (IOC) of the Integrated Terminal Weather System (ITWS). The Machine Intelligent Gust Front Algorithm (MIGFA) being deployed for ITWS uses multi-dimensional, knowledge-based signal processing techniques to detect and track gust fronts in Terminal Doppler Weather Radar (TDWR) data. Versions of MIGFA...
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Exploring the possibility of a low altitude gravity wave encounter as the cause of a general aviation accident near Norman Oklahoma on December 6, 1998
September 11, 2000
Conference Paper
Published in:
Proc. Ninth Conf. on Aviation, Range, and Aerospace Meteorology and 20th Conf. on Severe Local Storms, 11-15 September 2000, pp. J46-J49.
Summary
On December 6th, 1998, a fatal accident involving a twin engine Beech Baron occurred near the Max-Westheimer Airport at Norman Oklahoma (OUN). Although the National Transportation Safety Board (NTSB) conducted an extensive investigation into this accident, the probable cause for the accident has yet to be determined. Since the accident occurred outside of weather echoes that might be considered hazardous, it seems difficult to deduce a meteorological explanation for this accident. However, Doppler radar data suggested the presence of wave formations near the site of the accident. This report reflects examination of the data provided by the NTSB.
Summary
On December 6th, 1998, a fatal accident involving a twin engine Beech Baron occurred near the Max-Westheimer Airport at Norman Oklahoma (OUN). Although the National Transportation Safety Board (NTSB) conducted an extensive investigation into this accident, the probable cause for the accident has yet to be determined. Since the accident...
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FAA terminal convective weather forcast algorithm assessment
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 365-370.
Summary
Air traffic delay due to convective weather reached historically high levels in 1999, as passengers blamed airlines and airlines blamed the FAA for the massive inconveniences. While coordination between the FAA's System Command Center and the regional centers and terminals can be expected to improve with the FAA's new initiatives, it is clear that air traffic management and planning during convective weather will ultimately require accurate convective weather forecasts. In addition to improving system capacity and reducing delay, convective forecasts can help provide safer flight routes as well. The crash of a commercial airliner at Little Rock, AR in June 1999 after a one-hour flight from Dallas/Ft. Worth illustrates the dangers and potential tactical advantage that could be gained with frequently updated one-hour forecasts of convective storms. The Terminal Convective Weather Forecast (TCWF) product has been developed by MIT Lincoln Laboratory as part of the FAA Aviation Weather' Research Convective Weather Product Development Team (PDT). Lincoln began by consulting with air traffic personnel and commercial airline dispatchers to determine the needs of aviation users (Forman, et. al., 1999). Users indicated that convective weather, particularly line storms, caused the most consistent problems for managing air traffic. The "Growth and Decay Storm Tracker" developed by Wolfson et al. (1999) allows the generation of up to 1-hour forecasts of large scale, organized precipitation features with operationally useful accuracy. This patented technology. represents a breakthrough in short-term forecasting capability, providing quantitative envelope tracking as opposed to the usual cell tracking. This tracking technology is now being utilized in NCAR's AutoNowcaster (Mueller, et al., 2000), the National Convective Weather Forecast running at the Aviation Weather Center (Megenhardt, et al., 2000) and by private sector meteorological data vendors. The TCWF has been tested in Dallas/Ft. Worth (DFW) since 1998, in Orlando (MCO) since 1999, and in New York (NYC) since fiscal year 2000 began. These have been informal demonstrations, with the FAA William J. Hughes Technical Center (WJHTC) assessing utility to the users, and with MIT LL modifying the system based on user feedback and performance analyses. TCWF has undergone major revisions, and the latest build has now been deployed at all sites. The TCWF is now in a formal assessment phase at the Memphis international Airport as a prerequisite to an FAA operational requirement. The FAA Technical Center will make a recommendation on whether TCWF is suitable for inclusion in the FAA's operational integrated Terminal Weather System (ITWS), which has an unmet requirement for 30+ minute forecasts of convective weather. Memphis was selected for the TCWF Assessment since it has not been exposed to the forecast product during prior demonstrations. Operations began on March 24, 2000 and operational feedback is being assessed by the FAA Technical Center (McGettigan, et al., 2000) and MCR Corporation is performing a quantitative benefits assessment (Sunderlin and Paull, 2000). This paper details the refined TCWF algorithm and display concept, gives examples of the operational impact of terminal forecasts, and analyzes the technical performance of the TCWF during the early stages of the Memphis Assessment.
Summary
Air traffic delay due to convective weather reached historically high levels in 1999, as passengers blamed airlines and airlines blamed the FAA for the massive inconveniences. While coordination between the FAA's System Command Center and the regional centers and terminals can be expected to improve with the FAA's new initiatives...
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Distribution of Integrated Terminal Weather System (ITWS) products using web technology
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 147-152.
Summary
The Integrated Terminal Weather System (ITWS) is a capital investment of the Federal Aviation Administration (FAA) to provide a fully-automated, integrated terminal aviation weather information system that will improve the safety, efficiency, and capacity of major terminals. The ITWS acquires data from FAA and National Weather Service sensors as well as from aircraft in flight within the terminal area. Demonstration systems are being operated by the Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL) Weather Sensing Group at four airport terminal areas: New York, NY; Orlando, FL; Memphis, TN; and Dallas/Ft. Worth, TX. Real-time graphical weather information from the ITWS demonstration systems is relayed to primary users (airport towers, en route centers, TRACONS, the Command Center, and major airlines, etc.) via a situation display (SD) that consists of a Sun workstation and, a dedicated data line to the ITWS site. For users who do not have access to a fully operational SD or who want additional flexibility for accessing the ITWS information, MIT/LL operates a demonstration ITWS web server that provides the information for viewing with commercial-off-the-shelf (COTS) web browsers over the Internet and via the Collaborative Decision Making Network (CDMnet). This distribution of ITWS products has provided shared situational awareness between widely separated users. By sharing a common view of the same operational environment, controllers, dispatchers and other aviation decision makers and stakeholders have been better able to understand and coordinate the decisions that affect air traffic in the terminal area and surrounding en route airspace. In particular, by having up-to-the-minute weather information readily available to airline dispatch, safety during hazardous weather in the terminal area has been improved on a number of occasions at the ITWS demonstration sites (Evans, 2000). With the upcoming deployment of the ITWS as an operational FAA system to 44 major airports, a priority for the FAA is the distribution of the ITWS information from the production systems to airline dispatch and other non-FAA users. The operational ITWS is not designed to support SDS at the major airlines. Hence, distribution of ITWS information via a mechanism such as the Internet and the CDMnet is essential if the safety and coordination benefits achieved with the ITWS demonstration systems are to be obtained with the production ITWS. Because many airlines do not allow Internet access at all locations within the dispatch office, the current plan is to use CDMnet as the primary vehicle for ITWS data distribution to non-FAA users. However, to increase the availability of ITWS information to the broader ITWS user community, efforts are underway to make the data available on the Internet as well. Use of the Internet and CDMnet could also facilitate low-cost distribution of the ITWS information to additional FAA and non-FAA users alike. This paper describes the evolution of the ITWS demonstration web server, discusses the design of the web server and data processing, details how to access the web page and what products are currently available, presents some access statistics and current airline users, and discusses some future work which will allow for wide distribution of the production ITWS information.
Summary
The Integrated Terminal Weather System (ITWS) is a capital investment of the Federal Aviation Administration (FAA) to provide a fully-automated, integrated terminal aviation weather information system that will improve the safety, efficiency, and capacity of major terminals. The ITWS acquires data from FAA and National Weather Service sensors as well...
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Extending the Integrated Terminal Weather System (ITWS) to address urgent terminal area weather needs
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 153-158.
Summary
Major terminals and the surrounding en route airspace are critical elements of the US National Air System (NAS). A large fraction of the US population lives near these terminals, and the bulk of the hub connecting operations are at these airports as well. Adverse weather in these terminal areas and surrounding en route airspace is a major safety concern for the NAS as well as causing a large fraction of all US aviation delays. The principal weather decision support tool for these terminals is the Integrated Terminal Weather System (ITWS) which commenced full-scale development by the FAA in 1995, with first articles to be deployed shortly. In this paper, we discuss how the initial ITWS operational capability needs to be extended to address performance problems identified in operational use and to meet the many new user needs that have developed in the past five years. The paper proceeds as follows. In Section 2, we provide some necessary background on the ITWS operational capability, followed by a discussion of new capabilities to meet urgent user needs. Section 3 discusses refinements to the initial capability to address problems/issues that have been identified based on five years of operational use of ITWS products from ITWS demonstration systems at eight major airports. Next, we consider extending planned ITWS coverage to other major terminals. The final section summarizes the paper's results and suggests additional studies.
Summary
Major terminals and the surrounding en route airspace are critical elements of the US National Air System (NAS). A large fraction of the US population lives near these terminals, and the bulk of the hub connecting operations are at these airports as well. Adverse weather in these terminal areas and...
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Forecast aids to lessen the impact of marine stratus on San Francisco International Airport
September 11, 2000
Conference Paper
Published in:
Proc. Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 317-322.
Summary
San Francisco International Airport (SFO) is unable to use independent parallel approaches to its closely-spaced parallel runways when marine stratus is present in the approach. Delay programs are imposed to regulate the flow of traffic to match the true arrival capacity of the airport. Failure to forecast accurately the times of onset and dissipation of stratus in the approach results in unnecessary delays, costly airborne holding and diversions, or in wasted capacity as the traffic management planners fail to match the arrival rate to the actual airport capacity. Previous studies have shown that accurate 1-2 hour forecasts of the times of clearing in the approach could provide substantial reductions in the delays and inefficiencies associated with the marine stratus impacts on air traffic at SFO. The San Francisco Marine Stratus Initiative has provided a four-year focus on this problem and has resulted in the development of several forecast algorithms that will aid, the operational forecasting of the dissipation of marine stratus in the approach to SFO (Clark and Wilson, 1997). These algorithms involve new techniques for the analysis of observational data and statistical and dynamical prognosis of the behavior of the marine stratus. This discussion of the design and the performance of these algorithms provides an overview of the status of this project.
Summary
San Francisco International Airport (SFO) is unable to use independent parallel approaches to its closely-spaced parallel runways when marine stratus is present in the approach. Delay programs are imposed to regulate the flow of traffic to match the true arrival capacity of the airport. Failure to forecast accurately the times...
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ITWS and ITWS/LLWAS-NE runway alert performance at Dallas-Ft. Worth and Orlando
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 590-595.
Summary
The Integrated Terminal Weather System (ITWS) provides runway-orientated wind shear and microburst alerts to enhance the safety of flight operations at major U.S. airports. The alerts are reported as either losses or gains of airspeed, representing performance decreasing or performance increasing wind shears. The performance of ITWS as a stand-alone system has been thoroughly documented in previous research. During the 1994 ITWS Demonstration and Validation testing, the probability of detection (POD) and probability of false alarm (PFA) at Memphis (MEM) and Orlando (MCO) for all loss events were > 90 and < 5 percent, respectively, based on single-Doppler truth. The Low-Level Windshear Alert System-Network Expansion (LLWAS-NE) also generates runway alerts in the same format as ITWS. LLWAS-NE is not subject to viewing angle problems such as those experienced by single-Doppler radar. However, false alarms caused by LLWAS-NE sensor failures at some Terminal Doppler Weather Radar (TDWR) sites have reduced user confidence in the system. At those ITWS sites with an LLWAS-NE, the ITWS alerts derived from TDWR data will be integrated with LLWAS-NE alerts, hopefully to improve the performance. The ITWS integration algorithm is identical to the TDWR version, with the exception of a few adaptable parameter changes. The ITWS/LLWAS-NE parameters were modified slightly to account for ITWS and TDWR algorithm performance differences. In this paper, the performance of a stand-alone ITWS and the ITWS/LLWAS-NE integration algorithm at the MCO and Dallas-Ft. Worth (DFW) demonstration sites will be discussed. This assessment is considered unique since the radar and anemometer data were combined to create the runway truth. The focus of this research is to identify the shortcomings of both systems in order to recommend modifications that will improve the integration algorithm performance.
Summary
The Integrated Terminal Weather System (ITWS) provides runway-orientated wind shear and microburst alerts to enhance the safety of flight operations at major U.S. airports. The alerts are reported as either losses or gains of airspeed, representing performance decreasing or performance increasing wind shears. The performance of ITWS as a stand-alone...
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Medium Intensity Airport Weather System (MIAWS)
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 122-126.
Summary
Operational experience with the Integrated Terminal Weather Systems (ITWS) and Airport Surveillance Radar, Model 9, (ASR-9) Weather System Processor (WSP) demonstration systems, studies of pilot weather avoidance decision making), and recent accidents have demonstrated the need to provide timely, accurate information on the location and movement of storms to air traffic controllers, pilots, and airline dispatch. At medium-intensity airports, generally those with too few flight operations to justify the presence of Doppler radar systems like the Terminal Doppler Weather Radar (TDWR) or the WSP, terminal air traffic surveillance is currently provided with the ASR-7 and ASR-8 radar systems. The ASR-7 and ASR-8 do not provide calibrated precipitation intensity products or any storm motion information. The Medium-Intensity Airport Weather System (MIAWS) program is intended to address these terminal weather information deficiencies. MIAWS-generated products would be displayed to tower and Terminal Radar Approach Control (TRACON) supervisors and delivered to aircraft cockpits and airline dispatchers to assist pilots during landings. Initially, the MIAWS will provide a real time display of storm positions and motion based on Next Generation Weather Radar (NEXRAD) product data using a product generation and display system derived from the WSP. Airport wind and wind shear information will be acquired from an FAA Low Level Wind Shear Alert System (LLWAS). A demonstration system will be installed and demonstrated at experimental sites in Memphis, TN and Jackson, MS in 2000 and potentially at a third site in 2001. This demonstration system will be used to assess technical and operational issues such as compensation for the relatively slow updates of the NEXRAD products and, Anomalous Propagation (AP) ground clutter. The ASR-11 is a replacement for the ASR-7/8 radars that feature a weather reflectivity processing channel. When it becomes available at MIAWS locations, the MIAWS processor will acquire and display precipitation and storm movement products derived from the ASR-11. Likewise, when an LLWAS Relocation/Sustainment (LLWAS-RS) (Nilsen, et al., 1999) becomes available at MIAWS locations, the MIAWS will acquire wind and wind shear information derived from the LLWAS-RS.
Summary
Operational experience with the Integrated Terminal Weather Systems (ITWS) and Airport Surveillance Radar, Model 9, (ASR-9) Weather System Processor (WSP) demonstration systems, studies of pilot weather avoidance decision making), and recent accidents have demonstrated the need to provide timely, accurate information on the location and movement of storms to air...
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Measurement of hazardous winter storm phenomena at the Portland OR International Airport
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, ARAM, 11-15 September 2000, pp. 525-530.
Summary
Wind shear and lightning are classically associated with summertime convective weather events at airports east of Reno, NV. However, a recent study concluded that severe wind shear and lightning strike events occasionally occur during winter storms at west coast airports. One of the most surprising findings was that the Portland Oregon International Airport (PDX) has operationally significant vertical wind shear and a surprisingly high number of lightning strikes to aircraft within the terminal area during winter storms. The FAA has for a number of years planned to install an ASR-9 Weather System Processor (WSP) at PDX to provide protection against wind shear from microbursts and gust fronts. However, in view of the findings of the west coast weather study (conducted after the FAA's wind shear deployment study was completed, a research program was undertaken to: Better understand the phenomenology associated with the Portland winter storms; Determine whether the baseline ASR-9 Weather System Processor planned for PDX would adequately address operationally significant wind shear and other safety-related weather phenomena; and Identify alternative sensing/data fusion approaches to providing PDX terminal weather decision support if the WSP alone could not adequately provide safety warnings.
Summary
Wind shear and lightning are classically associated with summertime convective weather events at airports east of Reno, NV. However, a recent study concluded that severe wind shear and lightning strike events occasionally occur during winter storms at west coast airports. One of the most surprising findings was that the Portland...
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