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Sector workload model for benefits analysis and convective weather capacity prediction

Published in:
10th USA/Europe Air Traffic Management Research and Development Sem., ATM 2013, 10-13 June 2013.

Summary

En route sector capacity is determined mainly by controller workload. The operational capacity model used by the Federal Aviation Administration (FAA) provides traffic alert thresholds based entirely on hand-off workload. Its estimates are accurate for most sectors. However, it tends to over-estimate capacity in both small and large sectors because it does not account for conflicts and recurring tasks. Because of those omissions it cannot be used for accurate benefits analysis of workload-reduction initiatives, nor can it be extended to estimate capacity when hazardous weather increases the intensity of all workload types. We have previously reported on an improved model that accounts for all workload types and can be extended to handle hazardous weather. In this paper we present the results of a recent regression of that model using an extensive database of peak traffic counts for all United States en route sectors. The resulting fit quality confirms the workload basis of en route capacity. Because the model has excess degrees of freedom, the regression process returns multiple parameter combinations with nearly identical sector capacities. We analyze the impact of this ambiguity when using the model to quantify the benefits of workload reduction proposals. We also describe recent modifications to the weather-impacted version of the model to provide a more stable normalized capacity measure. We conclude with an illustration of its potential application to operational sector capacity forecasts in hazardous weather.
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Summary

En route sector capacity is determined mainly by controller workload. The operational capacity model used by the Federal Aviation Administration (FAA) provides traffic alert thresholds based entirely on hand-off workload. Its estimates are accurate for most sectors. However, it tends to over-estimate capacity in both small and large sectors because...

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Optimized airborne collision avoidance in mixed equipage environments

Published in:
MIT Lincoln Laboratory Report ATC-408

Summary

Developing robust collision avoidance logic that reliably prevents collision without excessive alerting is challenging due to sensor error and uncertainty in the future paths of the aircraft. Over the past few years, research has focused on the use of a computational method known as dynamic programming for producing an optimized decision logic for airborne collision avoidance. This report focuses on recent research on coordination, interoperability, and multiple-threat encounters. The methodology presented in this report results in logic that is safer and performs better than legacy TCAS. Modeling and simulation indicate that the proposed methodology can bring significant benefit to the current airspace and can support the need for safe, non-disruptive collision protection as the airspace continues to evolve.
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Summary

Developing robust collision avoidance logic that reliably prevents collision without excessive alerting is challenging due to sensor error and uncertainty in the future paths of the aircraft. Over the past few years, research has focused on the use of a computational method known as dynamic programming for producing an optimized...

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Risk-based modeling to support NextGen concept assessment and validation

Published in:
MIT Lincoln Laboratory Report ATC-405
Topic:

Summary

This report provides a brief review of major risk-based modeling (RBM) approaches, with particular emphasis on how these tools can be applied during initial Next Generation Air Transportation System (NextGen) concept development and how their use can be validated. Effective safety analysis should play a role even during a new system's concept definition and development. Elements of NextGen are currently progressing through these early phases. NextGen will increasingly rely on integrating multiple systems and information together to enable improved efficiency, safety, and reduced environmental impact. Ensuring that such complex interconnected systems are developed to meet safety goals requires corresponding advances in RBM and safety assessment approaches. This report does not cover the more detailed safety analyses that must be applied to mature system concepts. Rather, the focus is on approaches for hazard identification, scoping, and coarse risk estimation for systems in the early conceptual development stage, when details on the design and operation of the system have yet to be resolved. Risk models applied is this constrained context cannot be expected to provide the same complete, quantitative results as they do for mature systems. Following a review of prior models, this report continues with recommendations for RBM development, application, validation, and coordination between NextGen efforts. Also, a discussion on safety and concept development is provided.
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Summary

This report provides a brief review of major risk-based modeling (RBM) approaches, with particular emphasis on how these tools can be applied during initial Next Generation Air Transportation System (NextGen) concept development and how their use can be validated. Effective safety analysis should play a role even during a new...

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Measurements of the 1030 and 1090 MHz environments at JFK International Airport

Summary

Measurements of signals in the 1030 and 1090 MHz frequency bands have been made by MIT Lincoln Laboratory in the last several years, previously in the Boston area and most recently in April 2011, at JFK International Airport near New York City. This JFK measurement activity was performed as a part of the Lincoln Laboratory Traffic Alert and Collision Avoidance System (TCAS) work for the Federal Aviation Administration (FAA) and is the subject of this report. This report includes: 1) Overall characteristics of the 1030/1090 MHz environments, 2) Analysis of the TCAS air-to-air coordination process, 3) Examination of 1090 MHz Extended Squitter transmissions for use in TCAS, 4) Assessment of the extent and impact of TCAS operation on the airport surface.
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Summary

Measurements of signals in the 1030 and 1090 MHz frequency bands have been made by MIT Lincoln Laboratory in the last several years, previously in the Boston area and most recently in April 2011, at JFK International Airport near New York City. This JFK measurement activity was performed as a...

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Multifunction phased array radar (MPAR) spectral usage analysis

Published in:
MIT Lincoln Laboratory Report ATC-395

Summary

This report addressed two technical risks associated with replacing current air traffic and weather surveillance radars with a single type of multifunction phased array radar (MPAR). The first risk is whether radio spectrum usage would increase with the MPAR network and whether the allocated band will have enough spectral space. This question is addressed in two steps. First, single-radar spectrum usage is estimated based on certain assumptions regarding the radar design. Second, locations based on a previous radar placement study are used together with a terrain-dependent propagation model to compute the number of frequency channels needed at each site. We conclude that the overall spectrum usage is likely to increase with MPAR, but that the targeted window in S band will be able to accommodate the occupancy at all sites. The second risk is whether self-interference will limit the ability of the MPAR to operate asynchronously and adaptively on different antenna faces. This question is addressed by employing a simple bistatic ground clutter model to characterize the interference between adjacent faces. We conclude that some interference is unavoidable, but it would likely only occur during times when a transmit beam is at its maximum off-broadside angle (~2% of the time).
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Summary

This report addressed two technical risks associated with replacing current air traffic and weather surveillance radars with a single type of multifunction phased array radar (MPAR). The first risk is whether radio spectrum usage would increase with the MPAR network and whether the allocated band will have enough spectral space...

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A safety driven approach to the development of an airborne sense and avoid system

Published in:
AIAA Infotech at Aerospace Conf. and Exhibit, 19-21 June 2012.

Summary

Sense and avoid is the primary technical barrier to increased unmanned aircraft system airspace access. A safety assessment driven approach to sense and avoid system design and requirements validation is being employed to ensure safety and operational suitability. The foundation of this approach is a fast-time modeling and simulation architecture originally used to support the certification of the Traffic Alert and Collision Avoidance System. This paper describes the safety assessment methodology, including the architecture and evaluation metrics, and presents preliminary results for key system architecture and design tradeoffs.
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Summary

Sense and avoid is the primary technical barrier to increased unmanned aircraft system airspace access. A safety assessment driven approach to sense and avoid system design and requirements validation is being employed to ensure safety and operational suitability. The foundation of this approach is a fast-time modeling and simulation architecture...

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Next-generation airborne collision avoidance system

Published in:
Lincoln Laboratory Journal, Vol. 19, No. 1, 2012, pp. 17-33.

Summary

In response to a series of midair collisions involving commercial airliners, Lincoln Laboratory was directed by the Federal Aviation Administration in the 1970s to participate in the development of an onboard collision avoidance system. In its current manifestation, the Traffic Alert and Collision Avoidance System is mandated worldwide on all large aircraft and has significantly improved the safety of air travel, but major changes to the airspace planned over the coming years will require substantial modification to the system. Recently, Lincoln Laboratory has been pioneering the development of a new approach to collision avoidance systems that completely rethinks how such systems are engineered, allowing the system to provide a higher degree of safety without interfering with normal, safe operations.
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Summary

In response to a series of midair collisions involving commercial airliners, Lincoln Laboratory was directed by the Federal Aviation Administration in the 1970s to participate in the development of an onboard collision avoidance system. In its current manifestation, the Traffic Alert and Collision Avoidance System is mandated worldwide on all...

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Hazard alerting based on probabilistic models

Published in:
J. Guidance, Control, Dynamics, Vol. 35, No. 2, March-April 2012, pp. 442-450.

Summary

Hazard alerting systems alert operators to potential future undesirable events so that action may be taken to mitigate risk. One way to develop a hazard alerting system based on probabilistic models is by using a threshold-based approach, where the probability of the undesirable event without mitigation is compared against a threshold. Another way to develop such a system is to model the system as a Markov decision process and solve for the hazard experiments reveal that an expected utility approach performs better than threshold-based approaches when the dynamic stochasticity is high, where accounting for delays or changes in the alert becomes more important. however, for certain system parameters and operating environments, a threshold-based approach may provide comparable performance.
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Summary

Hazard alerting systems alert operators to potential future undesirable events so that action may be taken to mitigate risk. One way to develop a hazard alerting system based on probabilistic models is by using a threshold-based approach, where the probability of the undesirable event without mitigation is compared against a...

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U.S. Department of Transportation Federal Aviation Administration Field Demonstration #2: Final Report for Staffed NextGen Tower (SNT)

Published in:
MIT Lincoln Laboratory Report ATC-389

Summary

Staffed NextGen Towers (SNT), a research concept being developed and validated by the Federal Aviation Administration (FAA), is a paradigm shift to providing air traffic control services primarily via surface surveillance approved for operational use by controllers instead of the existing out-the-window (OTW) view at high-density airports. SNT was exercised as a prototype installed at the Dallas-Fortworth International Airport (DFW) during a two-week demonstration in the spring of 2011. MIT Lincoln Laboratory conducted this demonstration for the FAA in coordination with DFW air traffic control (ATC) and the DFW airport authority. This proof-of-concept demonstration used live traffic and was conducted by shadowing East tower operations from the DFW center tower, which is a back-up facility currently not typically used for air traffic control. The objective of this SNT field demonstration was to validate the supplemental SNT concept, to assess the operational suitability of the Tower Information Display System (TIDS) display for surface surveillance, and to evaluate the first iteration of prototype cameras in providing visual augmentation. TIDS provided surface surveillance information using an updated user interface that was integrated with electronic flight data. The cameras provided both fixed and scanning views of traffic to augment the OTW view. These objectives were met during the two-week field demonstration. DFW air traffic provided twelve controllers, three front line manager (FLMs), and three traffic management coordinators (TMCs) as test subjects. The twelve National Air Traffic Controllers Association (NATCA) DFW controllers "worked" the traffic according to their own techniques, using new hardware and software that included high resolution displays of surveillance data augmented by camera views. This equipment was designed to provide enhanced situational awareness to allow controllers to manage increased traffic volume during poor visibility conditions, leading to increased throughput. Results indicated that the likelihood of user acceptance and operational suitability is high for TIDS as a primary means for control, given surface surveillance that is approved for operational use. Human factors data indicated that TIDS could be beneficial. However, major technical issues included two display freezes, some incorrectly depicted targets, and display inconsistencies on TIDS. The cameras experienced numerous technical limitations that negatively influenced the human factors assessment of them. This report includes the percentages of human factors and technical success criteria that passed at DFW-2.
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Summary

Staffed NextGen Towers (SNT), a research concept being developed and validated by the Federal Aviation Administration (FAA), is a paradigm shift to providing air traffic control services primarily via surface surveillance approved for operational use by controllers instead of the existing out-the-window (OTW) view at high-density airports. SNT was exercised...

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A new approach for designing safer collision avoidance systems

Published in:
Air Traffic Control Q., Vol. 20, No. 1, January 2012, pp. 27-45.

Summary

The Traffic Alert and Collision Avoidance System significantly reduces the risk of mid-air collision and is mandated worldwide on transport aircraft. Engineering the avoidance logic was costly and spanned decades. The development followed an iterative process where the logic was specified using pseudocode, evaluated in simulation, and revised based on performance against a set of metrics. Modifying the logic is difficult because the pseudocode contains many heuristic rules that interact in complex ways. With the introduction of next-generation air traffic control procedures and surveillance systems, the logic will require significant revision to prevent unnecessary alerts. Recent work has explored an approach for designing collision avoidance systems that will shorten the development cycle, improve maintainability, and enhance safety with fewer false alerts. The approach involves computationally deriving optimized logic from encounter models and performance metrics. This paper outlines the approach and discusses the anticipated impact on development, safety, and operation.
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Summary

The Traffic Alert and Collision Avoidance System significantly reduces the risk of mid-air collision and is mandated worldwide on transport aircraft. Engineering the avoidance logic was costly and spanned decades. The development followed an iterative process where the logic was specified using pseudocode, evaluated in simulation, and revised based on...

READ MORE