Publications
Surveillance performance requirements for runway incursion prevention systems
September 26, 2001
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-301
Summary
In response to concerns over the number of runway incursions and runway conflicts at U.S. airports, the FAA is sponsoring research and development of safety systems for the airport surface. Two types of safety systems are being actively pursued, a tower cab alerting system and a runway status light system. The tower cab alerting system, called the Airport Movement Area Safety System (AMASS) is currently undergoing initial operational evaluation at several major airports. It provides aural and visual alerts to the tower cab to warn the controllers of potential traffic conflicts. The runway status light system is currently in the development phase, with initial operational suitability demonstrations planned at Dallas/Fort Worth International Airport during FY2003. Intended to offer protection in time-critical conflict scenarios where there is not enough time to warn the aircrews indirectly via the tower cab, the runway status light system provides visual indication of runway status directly to the cockpit; runway entrance lights warn pilots not to enter a runway on which there is approaching high-speed traffic; takeoff-hold lights warn pilots not to start takeoff if a conflict could occur. Both systems operate automatically, requiring no controller inputs. Activation commands for alerts and lights are generated by the systems' safety logic, which in turn receives airport traffic inputs from a surface surveillance and target tracking system. Accurate traffic representation is essential to meet system requirements, which include high conflict detection rate, prompt and accurate alerting and light activation, low nuisance and false alarm rates, and negligible interference with normal operations. This report analyzes the effect of the two fundamental surveillance performance parameters-position accuracy and surveillance update rate - on the performance of three different surface safety systems. The first two are the above-mentioned tower cab alerting and runway status light systems. The third system is a hypothetical cockpit alerting system that delivers alerts directly to the cockpit rather than to the tower cab. The surveillance accuracy and update rate requirements of these three systems are analyzed for three of the most common runway conflict scenarios, using realistic parameter values for aircraft motion. The scenarios are 1) a runway incursion by a taxiing aircraft in front of a departure or arrival, 2) a departure on an occupied runway, and 3) an arrival on an occupied runway. Runway status lights are especially effective at preventing incursions and accidents between takeoff or arrival aircraft and intersection taxi aircraft. Tower cab alerts are effective at alerting controllers to aircraft crossing or on a runway during an arrival. Runway status information provided directly to the cockpit will be required for the case where a previous arrival or a taxi aircraft fails to exit the runway as anticipated shortly before the arrival crossed the threshold. (not complete)
Summary
In response to concerns over the number of runway incursions and runway conflicts at U.S. airports, the FAA is sponsoring research and development of safety systems for the airport surface. Two types of safety systems are being actively pursued, a tower cab alerting system and a runway status light system...
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Assessing delay benefits of the Final Approach Spacing Tool (FAST)
August 6, 2001
Conference Paper
Published in:
AIAA Guidance, Navigation and control Conf., Vol. 3, 6-9 August 2001, pp. 1851-1859.
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Summary
Air traffic delay grows each year. NASA is developing the Final Approach Spacing Tool (FAST) to help reduce airport arrival delays. FAST is intended to increase throughput and reduce delays. Analysis and field trials have suggested that FAST can help controllers increase arrival throughput on busy runways by several aircraft per hour. Published simulation studies have predicted that delay reductions from such throughput increases would save several hundred million dollars annually. However, these predictions disagree on delay savings for some airports and omit other airports of interest. Their predicted delay savings for some airports are higher than actual reported delays for those airports. They do not consider hazardous weather disruptions to arrival routes, and they do not address downstream delays caused by schedule disruption. This paper focuses on simple statistical and analytical measures of delay to resolve these problems. It develops a rule for ranking benefits and compares delay reduction predictions against actual reported delays. It relates delay to ceiling and visibility and thunderstorms. It examines the correlation of delay between airports and estimates the impact of downstream delay on FAST benefits.
Summary
Air traffic delay grows each year. NASA is developing the Final Approach Spacing Tool (FAST) to help reduce airport arrival delays. FAST is intended to increase throughput and reduce delays. Analysis and field trials have suggested that FAST can help controllers increase arrival throughput on busy runways by several aircraft...
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Evaluation of Eta model forecasts as a backup weather source for CTAS
August 6, 2001
Conference Paper
Published in:
AIAA Guidance, Navigation and Control Conf.: a collection of Technical Papers, Vol. 3, 6-9 August 2001, pp. 1837-1842.
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Summary
Knowledge of present and future winds and temperature is important for air traffic operations in general, but is crucial for Decision Support Tools (DSTs) that rely heavily on accurately predicting trajectories of aircraft. One such tool is the Center-TRACON Automation System (CTAS) developed by NASA Ames Research Center. The Rapid Update Cycle (RUC) system is presently the principal source of weather information for CTAS. RUC provides weather updates on an hourly basis on a nationwide grid with horizontal resolution of 40 km and vertical resolution of 25 mb in pressure. However, a recent study of RUC data availability showed that the NWS and NOAA servers are subject to frequent service interruptions. Over a 210 day period (4/19/00-11/11/00), the availability of two NOAA and one NWS RUC server was monitored automatically. It was found that 60 days (29%) had periods of one hour or more where at least one server was out, with the longest outage lasting 13 hours on 9/21/00. In addition, there were 9 days (4%) for which all three servers were simultaneously unavailable, with the longest outage lasting 6 hours on 5/7/00. Moreover, even longer outages have been experienced with the RUC servers over the past several years. RUC forecasts are provided for up to 12 hours, but these are not currently used in CTAS as back up sources (except that the 1 or 2 hour forecasts are used for the current winds to compensate for transmission delays in obtaining the RUC data). Since RUC outages have been experienced for longer than 12 hours, it is therefore necessary to back RUC up with another weather source providing long-range forecasts. This paper examines the use of the Eta model forecasts as a back-up weather sources for CTAS. A specific output of the Eta km model, namely Grid 104, was selected for evaluation because its horizontal and vertical resolution, spatial extent and output parameters match most closely those of RUC. While RUC forecasts for a maximum of 12 hours into the future, Eta does so for up to 60 hours. In the event that a RUC outage would occur, Eta data could be substituted. If Eta data also became unavailable, the last issued forecasts could allow CTAS to continue to function properly for up to 60 hours. The approach used for evaluating the suitability of the Eta model and RUC forecasts was to compare them with the RUC analysis output or 0 hour forecast file, at the forecast time. Not surprisingly, it was found that the RUC model forecasts had lower wind magnitude errors out to 12 hours (the limit of the RUC forecasts) than the Eta model had. Hosever, the wind magnitude error for the Eta model grew only from 9 ft/s at 12 hours (comparable with RUC) to 11 ft/s at 48 hours. We therefore conclude that RUC forecasts should be used for outages up to 12 hours and Eta model forecasts should be used for outages up to 60 hours.
Summary
Knowledge of present and future winds and temperature is important for air traffic operations in general, but is crucial for Decision Support Tools (DSTs) that rely heavily on accurately predicting trajectories of aircraft. One such tool is the Center-TRACON Automation System (CTAS) developed by NASA Ames Research Center. The Rapid...
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The design and implementation of the new center/TRACON automation system (CTAS) weather distribution system
August 6, 2001
Conference Paper
Published in:
AIAA Guidance, Navigation and Control Conf.: a collection of Technical Papers, Vol. 3, 6-9 August 2001, pp. 1818-1836.
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Summary
The National Aeronautics and Space Administration (NASA), working with the Federal Aviation Administration (FAA), is developing a suite of decision support tools, called the Center/TRACON Automation System (CTAS). CTAS tools such as the Traffic Management Advisor (TMA) and Final Approach Spacing Tool (FAST) are designed to increase the efficiency of the air traffic flow into and through Terminal airspace. A core capability of CTAS is the Trajectory Synthesis (TS) software for accurately predicting an aircraft's trajectory. In order to compute these trajectories, TS needs an efficient access mechanism for obtaining the most up-to-date and accurate winds. The current CTAS weather access mechanism suffers from several major drawbacks. First, the mechanism can only handle a winds at a single resolution (presently 40-80 km). This prevents CTAS from taking advantage of high resolution wind from sources such as the Integrated Terminal Weather System (ITWS). Second, the present weather access mechanism is memory intensive and does not extend well to higher grid resolutions. This potentially limits CTAS in taking advantage of improvements in wind resolution from sources such as the Rapid Update Cycle (RUC). Third, the present method is processing intensive and limits the ability of CTAS to handle higher traffic loads. This potentially could impact the ability of new tools such as Direct-To and Multi-Center TMA (McTMA) to deal with increased traffic loads associated with adjacent Centers. In response to these challenges, M.I.T. Lincoln Laboratory has developed a new CTAS weather distribution (WxDist) system. There are two key elements to the new approach. First, the single wind grid is replaced with a set of nested grids for the TRACON, Center and Adjacent Center airspaces. Each and the grids are updated independently of each other. The second key element is replacement of the present interpolation scheme with a nearest-neighbor value approach. Previous studies have shown that this nearest-neighbor method does not degrade trajectory accuracy for the grid sizes under consideration. The new software design replaces the current implementation, known as the Weather Data Processing Daemon (WDPD), with a new approach. The Weather Server (WxServer) sends the weather grids to a Weather Client (WxClient) residing on each CTAS workstation running TS or PGUI (Planview Graphical User Interface) processes. The present point-to-point weather file distribution is replaced in the new scheme with a reliable multi-cast mechanism. This new distribution mechanism combined with data compression techniques greatly reduces network traffic compared to the present method. Other new processes combine RUC and ITWS data in a fail-soft manner to generate the multiple grids. The nearest-neighbor access method also substantially speeds up weather access. In combination with other improvements, the winds access speed is more than doubled over the original implementation.
Summary
The National Aeronautics and Space Administration (NASA), working with the Federal Aviation Administration (FAA), is developing a suite of decision support tools, called the Center/TRACON Automation System (CTAS). CTAS tools such as the Traffic Management Advisor (TMA) and Final Approach Spacing Tool (FAST) are designed to increase the efficiency of...
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Using surface surveillance to help reduce taxi delays
August 6, 2001
Conference Paper
Published in:
AIAA Guidance, Navigation and Control Conf.: a collection of Technical Papers, Vol. 3, 6-9 August 2001, pp. 1809-1817.
Summary
Taxi delay is the largest of all aviation movement delays. However, taxi-out delays have not received attention equal to that focused on airborne delays because taxi-out delays often result from downstream problems. Also, until recently, there was no practical means of tracking surface movements. New surface surveillance technology will revolutionize surface management by providing data for planning, timing, and monitoring surface operations. This paper proposes a simple aid to help manage departure taxi queues and help exploit existing departure capacity, while avoiding the delays that result from saturated queues and unbalanced runways. The proposed decision aide will use archived surveillance data to quantify queuing behavior and model departure capacity, and it will use real-time surveillance to track capacity changes and monitor the state of the taxi queues.
Summary
Taxi delay is the largest of all aviation movement delays. However, taxi-out delays have not received attention equal to that focused on airborne delays because taxi-out delays often result from downstream problems. Also, until recently, there was no practical means of tracking surface movements. New surface surveillance technology will revolutionize...
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ASR-9 Processor Augmentation Card (9-PAC) phase II scan-scan correlator algorithms
April 26, 2001
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-298
Summary
This report documents the scan-scan correlator (tracker) algorithm developed for Phase II of the ASR-9 Processor Augmentation Card (9-PAC) project. The improved correlation and tracking algorithms in 9-PAC Phase II decrease the incidence of false-alarm tracks and increase the detection of real aircraft. The tracker processing for 9-PAC Phase II defined in this document builds upon the prototype 9-PAC Phase II tracker describedin ATC-245. Tracker algorithms from Mode S (ATC-65) are also used in Phase II. This document describes the three main processing tasks of the tracker: initialization, input/output, and the actual correlation/tracking. The tracker itself is further broken down into four main functions: report-to-track association, report-to-track correlation, track update, and track initiation. Each of these functions is described in detail and is further broken down into sub-functions. In addition to the algorithm descriptions, the 9-PAC Phase II tracker system requirements are reviewed, and main data structures used in the 9-PAC Phase II tracker are defined.
Summary
This report documents the scan-scan correlator (tracker) algorithm developed for Phase II of the ASR-9 Processor Augmentation Card (9-PAC) project. The improved correlation and tracking algorithms in 9-PAC Phase II decrease the incidence of false-alarm tracks and increase the detection of real aircraft. The tracker processing for 9-PAC Phase II...
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An assessment of the communications, navigation, surveillance (CNS) capabilities needed to support the future Air Traffic Management System
January 10, 2001
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-295
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Summary
The purpose of this study was to assess the Communications, Navigation, and Surveillance (CNS) capabilities needed to support future Air Traffic Management (ATM) functionality in the National Airspace System (NAS). The goal was to determine the most effective areas for research and technical development in the CNS field and to make sure the decision support tools under development match future CNS capabilities. The requirements for future ATM functions were derived from high level operational concepts designed to provide more freedom and flexibility in flight operations and from the Joint Research Project Descriptions (JRPDs) that are listed in the Integrated Plan for Air Traffic Management Research and Technology Development. This work was performed for the FAA/NASA Interagency Air Traffic Management Integrated Product Team.
Summary
The purpose of this study was to assess the Communications, Navigation, and Surveillance (CNS) capabilities needed to support future Air Traffic Management (ATM) functionality in the National Airspace System (NAS). The goal was to determine the most effective areas for research and technical development in the CNS field and to...
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An operational concept for the Smart Landing Facility (SLF)
January 1, 2001
Conference Paper
Published in:
20th AIAA/IEEE Digital Avionics Systems Conf., 14-18 October 2001, pp. 6.C.2-1 - 6.C.2-8.
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Summary
This paper describes an operational concept for the Smart Landing Facility (SLF). The SLF is proposed as a component of the Small Aircraft Transportation System (SATS) and is envisioned to utilize Communication, Navigation, Surveillance and Air Traffic Management (CNS/ATM) technologies to support higher-volume air traffic operations in a wider variety of weather conditions than are currently possible at airports without an Air Traffic Control Tower (ATCT) or Terminal Radar Approach Control (TRACON). In order to accomplish this, the SLF will provide aircraft sequencing and separation within its terminal airspace (the SLF traffic area) and on the airport surface. The SLF infrastructure will provide timely and accurate weather and other flight information as well as traffic advisories. The SLF will provide a means to coordinate with nearby TRACONs or Air Route Traffic Control Centers (ARTCCs) to ensure proper integration of its traffic flows with those of adjacent airspace.
Summary
This paper describes an operational concept for the Smart Landing Facility (SLF). The SLF is proposed as a component of the Small Aircraft Transportation System (SATS) and is envisioned to utilize Communication, Navigation, Surveillance and Air Traffic Management (CNS/ATM) technologies to support higher-volume air traffic operations in a wider variety...
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Comparison of active TCAS slant range measurements with interpolated passive position reports for use in hybrid surveillance applications - measurements from the June 1999 Los Angeles Basin flight tests
October 17, 2000
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-294
Summary
Traffic Alert and Collision Avoidance System (TCAS) hybrid surveillance is a technique that makes use of both active surveillance data from the interrogation reply sequence and passive position estimates received from Mode S extended squitters. This technique allows TCAS to use passive surveillance once the data have been validated by comparison with active data. The maximum allowable range difference for validation specified by the International Civil Aviation Organization (ICAO) is 200 meters. Data from twenty encounters recorded during flight tests conducted in the Los Angeles Basin in June 1999 were analyzed. The results show that the ICAO specified limits were never exceeded and serve to validate the 200 meter limit.
Summary
Traffic Alert and Collision Avoidance System (TCAS) hybrid surveillance is a technique that makes use of both active surveillance data from the interrogation reply sequence and passive position estimates received from Mode S extended squitters. This technique allows TCAS to use passive surveillance once the data have been validated by...
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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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