Publications
Lessons learned designing an alternative CHI for en route air traffic control
April 27, 1999
Conference Paper
Published in:
Controller Centered HMI, 27-29 April 1999.
Summary
MIT Lincoln Laboratory is supporting the FAA-sponsored effort to design an operationally suitable Computer Human Interface (CHI) for the recently upgraded En Route Air Traffic Control Centers. All centers will soon receive new control consoles with state-of-the-art 20 square (2K by 2K resolution) color displays (currently operating in Seattle as of January 1999). The future CHI is being modeled on Eurocontrol's Operational Display and Input Development (ODID) CHI, as requested by active controllers in the US. The ODID-like CHI, with its minimal information display and color coded guidance, provides increased efficiency and productivity through employment of a modern graphical user interface. Lessons learned during the on-going design process, including research of look and feel issues in conjunction with data analysis from controller-in-the-loop testing of a prototype ODID-like CHI will be discussed. The Laboratory plans to model the alternative ODID-like CHI on the best of the European ODID, Denmark Sweden Interface (DSI) and EATCHIP CHI features, while cognizant of the FAA?s DSR capabilities and limitations to support an improved user interface. Human factors issues need resolution to provide a consistent look and feel across the Free Flight Phase 1 products and platforms, the Center TRACON Automation System (CTAS) and the User Request Evaluation Tool (URET). MIT Lincoln Laboratory has built a CHI Requirements Engineering Model (CREM) to support controller-in-the-loop testing of the ODID-like CHI, validate CHI requirements and determine applicable standards for the design of an integrated CHI. The CREM provides a means to assess various CHI alternatives and the capability to iterate options with controller teams to address user concerns. Lessons learned from the ODID-like CHI specification process will also be shared.
Summary
MIT Lincoln Laboratory is supporting the FAA-sponsored effort to design an operationally suitable Computer Human Interface (CHI) for the recently upgraded En Route Air Traffic Control Centers. All centers will soon receive new control consoles with state-of-the-art 20 square (2K by 2K resolution) color displays (currently operating in Seattle as...
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Development of improved TCAS II surveillance and interference limiting functions
January 1, 1999
Journal Article
Published in:
Air Traffic Control Q., Vol. 7, No. 1, 1999, pp. 19-46.
Summary
This paper describes the development and validation of improved TCAS II intruder surveillance tracking and interference limiting algorithms. Improvements in interference limiting were prompted by the FAA Spectrum Management Office and by international aviation administrations in order to further reduce interference to ground-based air traffic control surveillance by TCAS II. Improvements in surveillance tracking were prompted by aircarrier pilot organizations in order to increase the level of traffic situational awareness offered by the TCAS II display. The new algorithms are included in a proposed new version of TCAS II MOPS DO-185A which is commonly referred to as Change 7.0. TCAS II change 7.0 units will be introduced into the US airspace beginning as early as 1999 as part of a program to implement improvements in both TCAS II surveillance and collision avoidance.
Summary
This paper describes the development and validation of improved TCAS II intruder surveillance tracking and interference limiting algorithms. Improvements in interference limiting were prompted by the FAA Spectrum Management Office and by international aviation administrations in order to further reduce interference to ground-based air traffic control surveillance by TCAS II...
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TCAS II use of ADS-B surveillance data through hybrid surveillance
January 1, 1999
Journal Article
Published in:
Air Traffic Control Q., Vol. 7, No. 2, 1999, pp. 109-121.
Summary
This paper describes a technique that enables TCAS II to use passive surveillance data obtained via extended squitter, an implementation of automatic dependent surveillance broadcast (ADS-B). The technique, known as hybrid surveillance, is based upon the use of TCAS active surveillance to perform validation of the reported ADS-B position at track acquisition. Aircraft that pass initial validation are maintained on passive surveillance until they become a near threat. At that time, TCAS begins regular active surveillance and thus uses its current surveillance techniques for traffic and resolution advisories. In this way, TCAS is able to use passive extended squitter data while retaining its role as an independent monitor. Simulation results show that the use of passive information for non-threatening aircraft results in a significant decrease in TCAS interrogation rate. This enables TCAS to delay or avoid the range reduction that is now required in order for TCAS to remain within its interference budget in high traffic density airspace. Maintaining TCAS operating range in high density air-space enhances TCAS ability to support situational awareness for the flight crew.
Summary
This paper describes a technique that enables TCAS II to use passive surveillance data obtained via extended squitter, an implementation of automatic dependent surveillance broadcast (ADS-B). The technique, known as hybrid surveillance, is based upon the use of TCAS active surveillance to perform validation of the reported ADS-B position at...
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Airbus 320 performance during ATC-directed breakouts on final approach
November 20, 1998
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-265
Summary
An evaluation of Airbus 320 (A320) performance during ATC-directed breakouts was conducted in a two-part study during 1995. Phase 1 tested the combined effect of proposed ATC phraseology, pilot situational awareness training, and an A320-specific breakout procedure on performance. Pilot training included a briefing and viewing a videotape, but no simulator practice. Turn performance statistics from the Precision Runway Monitor Demonstration Program were used as the test criteria. Pilot preferences regarding procedures and the training material were also elicited. Three conclusions were: (1) breakout performance given the tested combination of pilot training and proposed ATC phraseology did meet the test criteria; (2) breakout performance given existing procedures did not meet the test criteria; and (3) the tested breakout procedure should be refined because it conflicted with other cockpit procedures and increased the transition time to a positive climb rate. Based on the results of this study, it is recommended that a combination of pilot situational awareness training, A320 breakout procedure, and modified ATC breakout phraseology equivalent to that tested in Phase 2 be employed for simultaneous parallel approach operations in instrument meteorological conditions.
Summary
An evaluation of Airbus 320 (A320) performance during ATC-directed breakouts was conducted in a two-part study during 1995. Phase 1 tested the combined effect of proposed ATC phraseology, pilot situational awareness training, and an A320-specific breakout procedure on performance. Pilot training included a briefing and viewing a videotape, but no...
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Techniques for improved reception of 1090 MHz ADS-B signals
October 31, 1998
Conference Paper
Published in:
17th DASC: Proc. of the 17th. Digital Avionics Systems Conf., 31 October - 7 November 1998, Vol. 2, pp. G25-1 - G25-9.
Summary
The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters and the associated position and status. Squitter reception includes the detection of the Mode S 1090 MHz waveform preamble, declaration of the bit and confidence values, error detection, and (if necessary) error correction. The current techniques for squitter reception are based upon methods developed for use in Mode S narrow-beam interrogators and for ACAS. In both of these applications, the rate of Mode NC fruit that is stronger than the Mode S waveform is relatively low, nominally less than 4,000 fruit per second. Extended squitter applications now include long range (up to 100 nmi) air-air surveillance in support of free flight. This type of surveillance is sometimes referred to as Cockpit Display of Traffic Information (CDTI). In high density environments, it is possible to operate with fruit rates of 40,000 fruit per second and higher. Operation of extended squitter in very high ModeNC fruit environments has led to the need to re-evaluate squitter reception techniques to determine if improved performance is achievable. The purpose of this paper is to provide a summary of work in progress to investigate improved squitter reception techniques. Elements of improved squitter reception being investigated include (1) the use of amplitude to improve bit and confidence declaration accuracy, (2) more capable error correction algorithms, and (3) more selective preamble detection approaches.
Summary
The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters...
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Multilateration on Mode S and ATCRBS signals at Atlanta's Hartsfield Airport
January 8, 1998
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-260
Summary
The ATC community is seeking a way to obtain aircraft ID and improved surveillance on the airport movement area. Surface radars provide good surveillance data, but do not provide ID, may not cover the whole movement area, and suffer from false reflection targets and performance degradations in rain. This report describes an evolutionary technique employing multilateration, TCAS technology, and existing ATCBI transponders to provide the desired surface surveillance information. Five multilateration receiver/transmitters (RTs) based on TCAS units, and a central multilateration computer processor were procured and installed on the highest available buildings on the perimeter of the north side of Atlanta's Hartsfield airport. The resulting coverage was such that there was a 93% probability that a multilateration position would be computed on a given Mode S short squitter emitted from a a target at a randomly selected position on the movement area. Multilateration was performed on ATCRBS targets using replies elicited by whisper shout methods originally developed for TCAS. Measurements showed that whisper shout was successful in degarbling targets that were in close proximity on the movement area. The probability of obtaining an ATCRBS multilateration position in a given one second interval depended on the number of whisper shout interrogations transmitted. The equipment required over 10 interrogations per target per second to obtain per second multilateration update rates on two typical targets of 58% and 83% respectively. This less than anticipated performance was primarily due to the inefficient whisper shout interrogation technique that was used in the test equipment. This can be corrected in next generation equipment. The multilateration accuracy was about 20 feet one sigma, as anticipated from theoretical considerations and previous experience with other equipment. By combining the multilateration data with ASDE data and tracking the results, it would be possible to obtain track reliabilities on the airport surface similar to that obtained elsewhere in the ATC system but update rates of 1Hz as required for surface surveillance and control purposes. The RTs were also capable of receiving Mode S long squitters containing GPS position information. The probability of at least one of the 5RTs receiving a given long squitter was essentially 100% on the movement area.
Summary
The ATC community is seeking a way to obtain aircraft ID and improved surveillance on the airport movement area. Surface radars provide good surveillance data, but do not provide ID, may not cover the whole movement area, and suffer from false reflection targets and performance degradations in rain. This report...
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Evaluation of Boeing 747-400 performance during ATC-directed breakouts on final approach
January 7, 1998
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-263
Summary
The effects of three different levels of pilot training on the breakout response of pilots and the Boeing 747-400 aircraft were studied. The study examined response during ATC-directed breakouts on final approach and was conducted in three phases. Phase 1 tested performance during manual and autopilot-coupled approaches given current procedures and pilot training. Phase 2 tested the effect of increased pilot situational awareness and proposed ATC breakout phraseology on breakouts during manual and autopilot-coupled approaches. Phase 3 tested the effect of two B747-400-specific breakout procedures on breakouts during autopilot-coupled approaches. Pilot preferences regarding procedures and the tested training materials were also solicited.
Summary
The effects of three different levels of pilot training on the breakout response of pilots and the Boeing 747-400 aircraft were studied. The study examined response during ATC-directed breakouts on final approach and was conducted in three phases. Phase 1 tested performance during manual and autopilot-coupled approaches given current procedures...
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The effects of compression-induced distortion of graphical weather images on pilot perception, acceptance, and performance
November 21, 1997
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-243
Summary
The Graphical Weather Service (GWS) is a data link application that will provide near-real-time graphical weather information to pilots in flight. To assess the effect GWS, as well as to aid in the proper design, implementation and certification of the use of GWS in aircraft, two human factors studies have been conducted. The second study conducted (Phase Two) is the topic of this report. Phase Two was conducted to determine the maximum level of compression-induced distortion that would be acceptable for transmission of weather images to the cockpit. To make this determination the following data were collected and analyzed: pilot subjective ratings of the perceived amount of distortion of a compressed image, pilot subjective ratings of the acceptability of a compressed image for use in the flight task, and pilot route selections as a function of the amount of compression presented in an image. Results indicated that images of low to moderate compression levels were generally acceptable for transmission to the cockpit, while images that were highly compressed were generally unacceptable. In addition, computed measures of image quality have been identified to enable the establishment of a criteria for transmitting images to aircraft.
Summary
The Graphical Weather Service (GWS) is a data link application that will provide near-real-time graphical weather information to pilots in flight. To assess the effect GWS, as well as to aid in the proper design, implementation and certification of the use of GWS in aircraft, two human factors studies have...
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The Weather-Huffman method of data compression of weather images
October 31, 1997
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-261
Summary
Providing an accurate picture of the weather conditions in the pilot's area of interest is a highly useful application for ground-to-air datalinks. The problem with using data links to transmit weather graphics is the large number of bits required to exactly specify the weather image. To make transmission of weather images practical, a means must be found to compress the data to a size compatible with a limited datalink capacity. The Weather-Huffman (WH) Algorithm developed in this report incorporates several subalgorithms in order to encode as faithfully as possible an input weather image within a specified datalink bit limitation. The main algorithm component is the encoding of a version of the input image via the Weather Huffman runlength code, a variant of the standard Huffman code tailored to the peculiarities of weather images. If possible, the input map itself is encoded. Generally, however, a resolution-reduced version of the map must be created prior to the encoding to meet the bit limitation. In that case, the output map will contain blocky regions, and higher weather level areas will tend to bloom in size. Two routines are included in WH to overcome these problems. The first is a Smoother Process, which corrects the blocky edges of weather regions. The second, more powerful routine, is the Extra Bit Algorithm (EBA). EBA utilizes all bits remaining in the message after the Huffman encoding to correct pixels set at too high a weather level. Both size and shape of weather regions are adjusted by this algorithim. Pictorial examples of the operation of this algorithm on several severe weather images derived from NEXRAD are presented.
Summary
Providing an accurate picture of the weather conditions in the pilot's area of interest is a highly useful application for ground-to-air datalinks. The problem with using data links to transmit weather graphics is the large number of bits required to exactly specify the weather image. To make transmission of weather...
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A description of the interfaces between the Weather Systems Processor (WSP) and the Airport Surveillance Radar (ASR-9)
June 16, 1997
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-259
Summary
The Weather Systems Processor (WSP) is an enhancement for the Federal Aviation Administration's (FAA) current generation Airport Surveillance Radars (ASR-9) that provides fully automated detection of microburst and gust front wind shear phenomena, estimates of storm cell movement and extrapolated future postion, and 10- and 20-minute predictions of the future postion of gust fronts. The WSP also generates six-level weather reflectivity free of anomalous propagation induced ground clutter breakthrough. Alphanumeric and graphical displays provide WSP-generated weather information to air traffic controllers and their supervisors. This report describes the hardware, interfaces, timing and digital signal extraction from the ASR-9 necessary to support the WSP. The digital interface circuitry between the WSP and the ASR-9, the control functions associated with the WSP, and the strategies for performing system test functions are described
Summary
The Weather Systems Processor (WSP) is an enhancement for the Federal Aviation Administration's (FAA) current generation Airport Surveillance Radars (ASR-9) that provides fully automated detection of microburst and gust front wind shear phenomena, estimates of storm cell movement and extrapolated future postion, and 10- and 20-minute predictions of the future...
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