Publications
Distribution of aviation weather hazard information: low altitude wind shear
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 499-504.
Topic:
R&D area:
Summary
Weather Hazard Information distribution is a necessary component for a successful system of weather hazard avoidance for aviation. It is a very important component, but not the only one. In order to be successful, a complete set of components must be included in the system: 1) Accurate Conceptual Model (Appropriate models of the physical process responsible for generating the hazard); 2) Production Infrastructure (System of tools [hardware, software and manpower]; the raw data feeds necessary for production of the hazard information and a standardized message format); 3) Quality Control Infrastructure (System of tools [hardware, software and manpower] & data feeds necessary for identifying and correcting erroneous information immediately); 4) Distribution Infrastructure (A method to relay, in a timely manner, only the information pertinent to the specific user); 5) Policies and Procedures (There must be clearly defined expectations of actions required of the users and recipients of the hazard information); 5) Training (The users and recipients as well as individuals responsible for production and quality control of the information must receive initial and recurrent training regarding actions required). ICAO in their Annex 3, Chapter 7 titled, SIGMET Information, Aerodrome Warnings and Wind Shear Warnings [ICAO 19981, describes in part one such system for weather hazard avoidance. ICAO does a good job defining the necessary production infrastructure. ICAO especially has been successful in defining the standardized message format. The format for SlGMETs is described in detail in Annex 3. But, an international organization Such as ICAO is limited in its scope of influence. Quality control of the SIGMET product and the distribution of the SIGMET is, in large part, beyond ICAO’s control. In addition, the actual weather hazard avoidance policies, procedures and training must be accomplished internally by each individual commercial aviation operator. Since each component listed above is directly dependent on the other five for a successful weather hazard avoidance system, Northwest Airlines (NWA) has chosen to attempt to address all six components of the system internally with use of the NWA Turbulence Plot System (TPS) [Fahey et. al. 2000].
Summary
Weather Hazard Information distribution is a necessary component for a successful system of weather hazard avoidance for aviation. It is a very important component, but not the only one. In order to be successful, a complete set of components must be included in the system: 1) Accurate Conceptual Model (Appropriate...
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FAA surveillance radar data as a complement to the WSR-88D network
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. J35-J39.
Summary
The U.S. Federal Aviation Administration (FAA) operates over 400 C- to L-band surveillance radars-Airport Surveillance Radars (ASRs), Air Route Surveillance Radars (ARSRs) and Terminal Doppler Weather Radars (TDWRs). Current generation terminal and en route aircraft surveillance radars (ASR-9, ASR-11 and ARSR-4) feature dedicated digital processing channels that measure and display precipitation reflectivity. Some of these "weather channels" will be upgraded to measure Doppler velocity, supporting, for example, wind shear detection at air terminals. The Terminal Doppler Weather Radar is a high quality dedicated meteorological surveillance radar deployed near many of the larger airports in the U.S. In this paper we consider how these radars could complement the WSR-88D network in providing a variety of meteorological services to the U.S. public. Potential benefits from a combined radar network would accrue from significantly increased radar density and the more rapid temporal updates of the FAA radars. Convective weather monitoring and forecasting, hydrological measurements and services to aviation are examples of areas where significant improvements could be expected. Section 2 reviews the status of the FAA radars their parameters, locations and capabilities. We also note the progress of various upgrade programs that will increase their weather surveillance capabilities substantially. In Section 3, we discuss benefits that would result from their usage in conjunction with the WSR-88D network. Finally, we discuss technological developments that will facilitate realization of these benefits.
Summary
The U.S. Federal Aviation Administration (FAA) operates over 400 C- to L-band surveillance radars-Airport Surveillance Radars (ASRs), Air Route Surveillance Radars (ARSRs) and Terminal Doppler Weather Radars (TDWRs). Current generation terminal and en route aircraft surveillance radars (ASR-9, ASR-11 and ARSR-4) feature dedicated digital processing channels that measure and display...
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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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Operational experience with weather products generated through joint use of FAA and NWS weather radar sensors
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology and 20th Conf. on Severe Local Storms, 11-15 September 2000, pp. J19-J23.
Summary
In this paper, we describe current joint use of Federal Aviation Administration (FAA) and National Weather Service (NWS) radar sensors to provide operational weather decision support for the FAA, airline operations centers, and NWS forecast offices. The capabilities that have been demonstrated include fully automatic data editing and short term "nowcast" product generation algorithms as well as display of data from the different radars in different windows; direct product distribution to operational decision makers without any intervening meteorologist input; and collaborative decision making between the various parties. The significant use of fully automated product generation algorithms has facilitated flexible, coordinated decision making in real time at many locations simultaneously, without the high personnel costs that would be required to achieve the same weather product generation capability manually through interpretation by experienced radar meteorologist/forecasters. These joint-use capabilities have been demonstrated operationally at the Integrated Terminal Weather System (ITWS) demonstration sites in Memphis, TN, Orlando, FL, Dallas, TX, and Garden City, NY. These sites have provided operational service for the four major terminal areas since 1994.1 Specific capabilities used operationally by FAA- and airline users, which are discussed in the next section, include: 1. Addressing radar data quality issues such as rain attenuation and AP-induced ground clutter contamination, 2. High update rates for detection of rapidly changing weather while also obtaining 3D information on storms, 3. Estimating 3D winds, and 4. Reducing the fraction of phenomena that are not accurately characterized because the radars can directly measure radial velocity only. Section 3 discusses the operational usage of integrated products by NWS forecast offices at the ITVVS demonstration sites. The paper concludes with a summary of the operational uses to date and makes some suggestions for NWS and USAF use of FAA radar sensors in conjunction with NEXt generation weather RADars (NEXRAD).
Summary
In this paper, we describe current joint use of Federal Aviation Administration (FAA) and National Weather Service (NWS) radar sensors to provide operational weather decision support for the FAA, airline operations centers, and NWS forecast offices. The capabilities that have been demonstrated include fully automatic data editing and short term...
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Weather sensing and data fusion to improve safety and reduce delays at major west coast airports
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 102-107.
Summary
In this paper we present results from a recently completed study of weather sensing and data fusion to improve safety and reduce delays at major west coast airports. With the exception of a summer stratus burn-off prediction project at San Francisco, these airports have received much less attention in terms of advanced FAA terminal weather decision support systems than major airports east of Los Angeles. This is because the principal concern for terminal weather decision support to date has been microburst-induced wind shear, which is very infrequent at the west coast airports. However, three factors warrant a reexamination of weather decision support provided to these major west coast airports: 1. The increased emphasis on significantly improving aviation safety while reducing delays at major airports in the face of expected increases in operations rates within the National Airspace System (NAS), 2. New air traffic management technology such as terminal automation, collaborative decision making (CDM), and weather adaptive wake vortex spacing systems, and 3. Advances in terminal weather decision support technology represented by the Integrated Terminal Weather System (ITWS) [including various P31 enhancements to ITWS (Evans and Wolfson, 2000)] The airports considered in this study were the Los Angeles (LAX), San Francisco (SFO), Portland (PDX) and Seattle (SEA) International Airports. It should be noted that because these airports did not receive a Terminal Doppler Weather Radar, there currently is no plan to provide them with an ITWS. LAX, SF0 and PDX are scheduled to receive an ASR-9 Weather System Processor (WSP). The paper proceeds as follows. Section 2 discusses the study's methodology and provides background information on delays and weather phenomena for these airports in the context of other major US airports as well as applicable air traffic management (ATM) and terminal weather system technology. Section 3 summarizes the principal findings for the four airports. We conclude with a summary of the potential benefits of improved weather sensing and data fusion that might be provided at these west coast airports by an augmented ITWS as well as recommendations for further studies.
Summary
In this paper we present results from a recently completed study of weather sensing and data fusion to improve safety and reduce delays at major west coast airports. With the exception of a summer stratus burn-off prediction project at San Francisco, these airports have received much less attention in terms...
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The Beacon Target Detector (BTD) algorithms deployed in the ASR-9 Processor Augmentation Card (9-PAC)
September 5, 2000
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-288
Summary
This project report describes the Beacon Target Detector (BTD) algorithms implemented in the ASR-9 Processor Augmentation Card (9-PAC). The BTD function combines replies that arise from the same aircraft to form beacon targets, and sends these beacon targets to the 9-PAC merge process where they are combined with primary radar targets. The 9-PAC BTD algorithm was designed to solve two problems with the ASR-9 Array Signal Processor (ASP) BTD: identifying and removing false beacon targets due to reflections, and preventing merging or splitting of targets due to reply overlap and garble. The BTD reflection processing algorithm marks each beacon target as either real or false, and provides this information to the 9-PAC merge process. Discrete Mode 3/A reflection false targets are identified when duplicate code reports satisfying stringent conditions are located. In order to find non-discrete Mode 3/A code reflection false targets, the BTD builds an automated, dynamic reflector database based on the geography of real and false targets with discrete Mode 3/A codes. This report supersedes an earlier report (ATC-220) which described the 9-PAC BTD algorithms prior to the operational field testing effort conducted by the FAA in 1995 and 1996. Nationwide deployment of 9-PAC on production hardware was approved in April 1999. To date, more than 60 installations have been performed, and hardware has been procured to update all 134 ASR-9s in the National Airspace System.
Summary
This project report describes the Beacon Target Detector (BTD) algorithms implemented in the ASR-9 Processor Augmentation Card (9-PAC). The BTD function combines replies that arise from the same aircraft to form beacon targets, and sends these beacon targets to the 9-PAC merge process where they are combined with primary radar...
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