Publications
Potential benefits of reducing wake-related aircraft spacing at the Dallas/Fort Worth International Airport
July 12, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-304
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Summary
Measurements and modeling of wake vortices reveal that the Federal Aviation Administration's (FAA) minimum separation requirements for departing aircraft are often overly conservative. If the separation times following heavy aircraft can be safely reduced, considerable savings will be realized. The Dallas/Fort Worth International Airport (DFW) experiences departure delays daily. Banks of departing aircraft often create a significant queue at the end of the runway, with aircraft waiting between 10-20 minutes to depart. Additional delays occur during weather recovery operations after the terminal airspace has been impacted by thunderstorms. This report produces projected delay and cost benefits of implementing reduced wake spacing for departing aircraft at DFW. The benefits are calculated by simulating aircraft departures during both clear weather and weather recovery operations, using current and possible reduced spacings. The difference in delay values using different separation standards is used to calculate a cost savings to the airlines. The benefits for a single day are extended to a yearly approximation based on the estimated number of days that the separation criteria could be safely reduced. Departure information from February 19, 2001 is analyzed for clear weather operations. The simulation reveals a savings of $4.7 million/yr when the separation criteria is reduced from the current practice of 110 seconds to 90 seconds. A further reduction in the separation criteria to 60 seconds pushes the maximum savings to almost $10 million/yr. The daily savings for a weather recovery operation is $19,600 for weather impacts between 15-60 minutes and a reduction in spacing fiom the current 110 seconds to 90 seconds. The average increases to $36,200 when the spacing is reduced to 60 seconds. Significant thunderstorm events impacted the DFW terminal airspace 59 times during 2001 leading to projected yearly savings of greater than $2.1 million for a 60 second separation criteria following heavies.
Summary
Measurements and modeling of wake vortices reveal that the Federal Aviation Administration's (FAA) minimum separation requirements for departing aircraft are often overly conservative. If the separation times following heavy aircraft can be safely reduced, considerable savings will be realized. The Dallas/Fort Worth International Airport (DFW) experiences departure delays daily. Banks...
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ASR-9 Weather Systems Processor (WSP) signal processing algorithms
June 25, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-255
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Summary
Thunderstorm activity and associated low-altitude wind shear constitute a significant safety hazard to aviation, particularly during operations near airport terminals where aircraft altitude is low and flight routes are constrained. The Federal Aviation Administration (FAA) has procured several dedicated meteorological sensors (Terminal Doppler Weather Radar (TDWR), Network Expansion Low Level Wind Shear Alert System (LLWAS) at major airports to enhance the safety and efficiency of operations during convective weather. A hardware and software modification to existing Airport Surveillance Radars (ASR-9)-the Weather Systems Processor (WSP)-will provide similar capabilities at much lower cost, thus allowing the FAA to extend its protection envelope to medium density airports and airports where thunderstorm activity is less frequent. Following successful operation demonstrations of a prototype ASR-WSP, the FAA has procured approximately 35 WSP's for nationwide deployment. Lincoln Laboratory was responsible for development of all data processing algorithms, which were provided as Government Furnished Equipment (GFE), to be implemented by the full-scale development (FSD) contractor without modification. This report defines the operations that are used to produce images of atmospheric reflectivity, Doppler velocity and data quality that are used by WSP's meteorological product algorithms to generate automated information on hazardous wind shear and other phenomena. Principle requirements are suppression of interference (e.g. ground clutter, moving points targets, meteorological and ground echoes originating from beyond the radar's unambiguous range), generation of meteorologically relevant images and estimates of data quality. Hereafter, these operations will be referred to as "signal processing" and the resulting images as "base data."
Summary
Thunderstorm activity and associated low-altitude wind shear constitute a significant safety hazard to aviation, particularly during operations near airport terminals where aircraft altitude is low and flight routes are constrained. The Federal Aviation Administration (FAA) has procured several dedicated meteorological sensors (Terminal Doppler Weather Radar (TDWR), Network Expansion Low Level...
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Machine intelligent gust front algorithm for the WSP
June 10, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-274
Summary
The Machine Intelligent Gust Front Algorithm (MIGFA) utilizes multi-dimensional image processing and fuzzy logic techniques to identify gust fronts in Doppler radar data generated by the ASR-9 Weather Systems Processor (WSP). The algorithm generates products that support both safety and planning functions for ATC. Outputs include current and predicted locations of gust fronts, as well as estimates of the wind shear and wind shift associated with each gust front. This document provides both high level and detailed functional descriptions of FAA build 2.0 of the WSP MIGFA. The document was written with many explicit references to data structures and routines in the actual software in order that it may serve as a useful algorithm development and programmers reference guide.
Summary
The Machine Intelligent Gust Front Algorithm (MIGFA) utilizes multi-dimensional image processing and fuzzy logic techniques to identify gust fronts in Doppler radar data generated by the ASR-9 Weather Systems Processor (WSP). The algorithm generates products that support both safety and planning functions for ATC. Outputs include current and predicted locations...
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A web-based display and access point to the FAA's Integrated Terminal Weather System (ITWS)
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 206-209.
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The Integrated Terminal Weather System (ITWS) is a high-resolution weather information system designed to operate within the TRACONs surrounding the country's major airports. Targeted for those airports most often adversely affected by convective weather, the system was developed for the Federal Aviation Administration (FAA) by the Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL) Weather Sensing Group. The ITWS acquires data from Next Generation Radars (NEXRAD), Terminal Doppler Weather Radars (TDWR), Airport Surveillance Radars (ASR-9), Low Level Windshear Alert Systems (LLWAS), the National Lightning Detection Network (NLDN), Automated Weather Observing Stations (AWOS/ASOS), and aircraft in flight. The system integrates the data to provide consistent weather information in a form that is usable without further meteorological interpretation. This information includes six-level precipitation at a number of ranges, windshear and microburst detection and prediction, storm motion and extrapolated position, wind fields, gust fronts, lightning, and storm cell information (hail, mesocyclone notification, and echo tops). A set of direct users of ITWS (FAA users at TRACONs, Air Traffic Control Towers, and en-route centers) will receive ITWS weather products through FAA-provided Situation Displays (SDs) that are tied directly to the ITWS processor. In addition, the FAA has sponsored development of an ITWS External Users Data Distribution System to provide real-time ITWS products to those users who do not have access to a dedicated SD. The data distribution system is being developed in conjunction with the upcoming deployment of the ITWS (2002-2004) as an operational FAA system serving 47 major airports. The need for a remotely accessible display is strongly supported by draft recommendations recently released by the National Transportation Safety Board (NTSB) that call for U.S. air carriers and all air traffic control facilities to have access to data from FAA terminal weather information systems. In addition, the Collaborative Decision Making program (CDM) has highlighted the need to make the information widely available to airlines. MIT/LL has operated demonstration ITWS systems since 1994, and a demonstration website since 1997. Most major airlines have successfully accessed the ITWS demonstration products in real time via Web browsers and have used this information to improve safety and reduce delays (Maloney, 2000). Benefits specific to airline dispatch include support for decisions made during diversion situations and improvements in hub operations . 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 (Evans 2000). This paper describes the goals of the ITWS External Users Data Distribution System development project, including a discussion of the system architecture, data distribution and access methods, and the web-based interface.
Summary
The Integrated Terminal Weather System (ITWS) is a high-resolution weather information system designed to operate within the TRACONs surrounding the country's major airports. Targeted for those airports most often adversely affected by convective weather, the system was developed for the Federal Aviation Administration (FAA) by the Massachusetts Institute of Technology's...
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An improved gust front detection capability for the ASR-9 WSP
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 379-382.
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The Weather Systems Processor (WSP) is being deployed by FAA at 35 medium and high-density ASR-9 equipped airports across the United States. The Machine Intelligent Gust Front Algorithm (MIGFA) developed at Lincoln Laboratory provides important gust front detection and tracking capability for this system as well as other FAA systems including Terminal Doppler Weather Radar (TDWR) and Integrated Terminal Weather System (ITWS). The algorithm utilizes multidimensional image processing, data fusion, and fuzzy logic techniques to recognize gust fronts observed in Doppler radar data. Some deficiencies in algorithm performance have been identified through ongoing analysis of data from two initial limited production WSP sites in Austin, TX (AUS) and Albuquerque, NM (ABQ). At AUS, the most common cause of false alarms is bands of low-reflectivity rain echoes having shapes and intensities similar to gust front thin line echoes. Missed or late detections have occasionally occurred when gust fronts are near or embedded in the leading edge of approaching line storms, where direct radar evidence of the gust front (e.g.. thin line echo, velocity convergence) may be fragmented or absent altogether. In ABQ, "canyon wind" events emanating, from mountains located just east of the airport occur with very little lead time, and often with little or no radar signatures, making timely detection on the basis of the radar data alone difficult. MIGFA is equipped with numerous parameters and thresholds that can be adjusted dynamically based on recognition of the local or regional weather context in which it is operating. Through additional contextual weather information processing, this dynamic sensitization capability has been further exploited to address the deficiencies noted above, resulting in an appreciable improvement in performance on data collected at the two WSP sites.
Summary
The Weather Systems Processor (WSP) is being deployed by FAA at 35 medium and high-density ASR-9 equipped airports across the United States. The Machine Intelligent Gust Front Algorithm (MIGFA) developed at Lincoln Laboratory provides important gust front detection and tracking capability for this system as well as other FAA systems...
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An evaluation of the Medium-Intensity Airport Weather System (MIAWS) products at the Memphis, TN and Jackson, MS International Airports
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology (13th Conf. on Applied Climatology), 13-16 May 2002, pp. J118-J122.
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The FAA is procuring aviation weather systems, which are designed to enhance safety/capacity and reduce delays at U.S. airports. The two most widely publicized systems currently being installed are the Integrated Terminal Weather System (ITWS) at airports equipped with a Terminal Doppler Weather Radar (TDWR) and the Weather System Processor (WSP) at those terminal areas covered by an Airport Surveillance Radar, Model 9 (ASR-9). At airports not slated to receive either an ITWS or WSP, an emerging system coined the Medium Intensity Airport Weather System (MIAWS) will be installed. Currently, either an ASR-7 or 8 provides terminal aircraft surveillance at these airports. Unfortunately, these platforms do not output calibrated precipitation intensity or storm motion information. Quantitative six-level weather reflectivity data will be available once the digitally enhanced ASR-11 radar system is operational at MIAWS supported sites. The Low Level Wind Shear Alert System - Relocation/Sustainment (LLWAS-RS) anemometer network will provide MIAWS with surface-based winds and wind shear alerts. The rationale for MIAWS evolved from the ITWS and WSP prototype testing. The premise is that the calibrated reflectivity and velocity data from state-of-the-art radar platforms can be utilized to produce a suite of current and forecasted storm positions to aid air traffic control decision making. The forecasted location is a critical issue if the storms are moving rapidly. This can lead to a scenario where the weather conditions deteriorate significantly within a matter of minutes. Once implemented, MIAWS will be an essential component of the National Airspace System by providing this evolving technology to airports whose traffic counts are not sufficient to warrant either an ITWS or WSP, but where commercial carriers could reap the benefits of a high-quality weather radar system. The FAA has contracted the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL) to undertake a proof-of-concept evaluation of MIAWS. To this end, MIT/LL installed two prototype systems at the Jackson, MS (JAN) and Memphis, TN (MEM) International Airports. The system at MEM is used solely for product evaluation and refinement, while the FAA is operationally evaluating the JAN MIAWS. The focus of this report is a preliminary assessment of the capabilities and limitations of MIAWS in its current implementation, i.e. precipitation based solely on NEXRAD data. Potential enhancements to the NEXRAD product data and MIAWS algorithms will also be discussed.
Summary
The FAA is procuring aviation weather systems, which are designed to enhance safety/capacity and reduce delays at U.S. airports. The two most widely publicized systems currently being installed are the Integrated Terminal Weather System (ITWS) at airports equipped with a Terminal Doppler Weather Radar (TDWR) and the Weather System Processor...
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Development of automated aviation weather products for ocean/remote regions: scientific and practical challenges, research strategies, and first steps
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 57-60.
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From the common and recognizable occurrence of convection, to the sporadic and far less visible reach of volcanic ash, meteorological phenomena impose diverse challenges to the efficiency, economic viability, and safety of flight operations across the global oceans. Those challenges are compounded by special difficulties associated with nowcasting and forecasting for remote areas, such as expansive voids in surface observations and soundings, large forecast domains, communications difficulties, and long-duration flights often needing significant forecast updates. Conspicuously lacking over oceans are the observational capabilities that provide key information about the internal structure of convection - notably radar and lightning detection systems. The long-term oceanic weather development program (OW) outlined here seeks to use improved understanding of the phenomenology of oceanic weather hazards along with new observations, model information and processing tools to fashion automated forecast/briefing products supporting remote oceanic routes. A parallel OW objective (outlined by Lindholm and Bums, 2002, this conference volume) supports in-flight product transfer to the cockpit. Established in March, 2001, the OW program is still in its infancy. Thus, we concentrate here upon strategy and the scientific basis for our plans. Although our work has begun with a focus on low and middle latitudes (Pacific, Atlantic and Gulf of Mexico regions), increasing use of polar routes is likely to raise the priority for products tailored to high latitude regions over the next several years.
Summary
From the common and recognizable occurrence of convection, to the sporadic and far less visible reach of volcanic ash, meteorological phenomena impose diverse challenges to the efficiency, economic viability, and safety of flight operations across the global oceans. Those challenges are compounded by special difficulties associated with nowcasting and forecasting...
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En route weather depiction benefits of the NEXRAD vertically integrated liquid water product utilized by the Corridor Integrated Weather System
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 120-123.
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It is demonstrated in this paper that weather depictions in an operational environment based upon VIL provide more meaningful information for en route traffic routing than a BREF product. VIL precipitation proves advantageous in limiting contamination from Anomalous Propagation (AP) ground clutter, biological targets (e.g., birds and insects), and radar artifacts. The extended vertical coverage of VIL sampling also better depicts storm cells as they first develop, further assisting traffic managers achieve more efficient use of tactical airspace when weather occurs unexpectedly.
Summary
It is demonstrated in this paper that weather depictions in an operational environment based upon VIL provide more meaningful information for en route traffic routing than a BREF product. VIL precipitation proves advantageous in limiting contamination from Anomalous Propagation (AP) ground clutter, biological targets (e.g., birds and insects), and radar...
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The Corridor Integrated Weather System (CIWS)
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 210-215.
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The FAA Operational Evolution Plan (OEP) identified en route severe weather as one of the four problems that must be addressed if the US. air transportation system is to alleviate the growing gap between the demand for air transportation and the ability of the system to meet that demand. Convective weather in highly congested airspace is of particular concern because many of the delays arise from these corridors. For example, rerouting aircraft around areas of actual or predicted weather can be very difficult when one must be concerned about controller overload in the weather free sectors. When major terminals also underlie the en route airspace, convective weather has even greater adverse impacts. The principal thrust to date in addressing this problem has been "strategic" collaborative routing as exemplified by the "Spring 2000" and "Spring 2001" initiatives. However, success of the strategic approach embodied in these initiatives depends on the ability to accurately forecast convective weather impacts two or more hours in advance. Limitations in the forecast accuracy necessitate development of a companion "tactical" convective weather capability. In this paper, we describe a major new FAA initiative, the Corridor Integrated Weather System (CIWS). The objective of this project, which is currently in the concept exploration phase, is to improve tactical convective weather decision support for congested en route airspace. A real time operational demonstration, which was begun in July 2001 in the Great Lakes corridor, will be extended to the Northeast corridor in 2002. In the sections that follow, we describe the operational needs that motivated the ClWS initiative, the technology under investigation, the concept exploration test bed and summer 2001 operational experience, and the near term plans for the CIWS concept exploration.
Summary
The FAA Operational Evolution Plan (OEP) identified en route severe weather as one of the four problems that must be addressed if the US. air transportation system is to alleviate the growing gap between the demand for air transportation and the ability of the system to meet that demand. Convective...
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Low altitude boyancy wave turbulence - a potential aviation safety threat
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 375-378.
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Weather comprises one of the most significant safety hazards facing civilian aviation today. This hazard has been significantly reduced by the development and use of microburst wind shear detection technologies such as the Low Level Wind Shear Alert System (LLWAS), the Terminal Doppler Weather Radar (TDWR), the ASR-9 Weather Systems Processor (WSP) and the Integrated Terminal Weather System (ITWS). Each was designed to detect and warn for the presence of low altitude wind shear resulting from microburst and gust fronts. These systems have made an unquestionable improvement in aviation safety; however, there are other forms of low altitude wind shear hazardous to aviation. This paper provides a description of a low altitude buoyancy wave (BW) induced turbulence phenomena that appears to also be a significant hazard to aviation. Buoyancy wave turbulence can be particularly dangerous since it often occurs outside regions containing intense precipitation where pilots typically expect to encounter thunderstorm induced wind shear conditions. Section 2 of this paper contains a general description of BW phenomena based on laboratory and observational studies. Section 3 will briefly summarize several incidents where commercial and civilian aircraft have encountered buoyancy waved induced turbulence. A summary and conclusions are made in section 4.
Summary
Weather comprises one of the most significant safety hazards facing civilian aviation today. This hazard has been significantly reduced by the development and use of microburst wind shear detection technologies such as the Low Level Wind Shear Alert System (LLWAS), the Terminal Doppler Weather Radar (TDWR), the ASR-9 Weather Systems...
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