Arthur P. Smith

Methods for maintaining benefits for merging aircraft on terminal RNAV routes

Current terminal operations are changing as more terminal area navigation (RNAV) routes are defined that aircraft are expected to fly. Previously, arriving aircraft filing a standard terminal arrival route (STAR) were given vectors to guide them to the runway when the aircraft transitions from the STAR and enters the terminal area. There are, however, efforts underway to extend these STARs as routes in the terminal area that overlay the current traffic patterns resulting from the vectors that controllers give to the aircraft. With the introduction of more terminal RNAV arrival procedures, anticipated benefits range from reduced voice communication, improved situational awareness, reduced flying time and distance, improved predictability to increased throughput. However, to achieve these benefits, the aircraft must remain on the planned RNAV routes. This is a change in paradigm from the current practice of vectoring the aircraft to achieve the proper sequence and spacing in the terminal area. This paper reports on a concept for allowing the aircraft to remain on RNAV routes while managing the flow of the aircraft to the final approach segment. The concept discussed in this paper is part of a broader suite of concepts currently being investigated to address merging and spacing problems arising from structured RNAV and required navigation performance (RNP) routes in the terminal environment. This suite of concepts is referred to as spacing of performance-based arrivals on converging routes (SPACR) and is intended to address the near-term merging and spacing problem, relying on existing cockpit and ground automation capabilities. SPACR includes applications of cockpit capabilities such as FMS offsets and required time of arrival (RTA) and ground automation functionalities such as the embedded ghosting function in the STARS and new STARS graphical user interface (GUI) functionalities. The concept described in this paper involves using the current implementation of the converging runway display aid (CRDA) as a controller aid to visualize the relative spacing for uncoordinated terminal merges with speed control and the lateral offset function of many current flight management systems (FMS) to resolve spacing problems. A parametric analysis was performed of the controllability of such a concept and a controller-in-the-loop simulation using typical terminal area geometry was run to explore several issues. These issues include mixed equipage, route design and airspace usage as well as initial thoughts on controller acceptance. The results of the analysis and simulation as they pertain to maintaining terminal RNAV benefits are reported in this paper.

Near-term solution for efficient merging of aircraft on uncoordinated terminal RNAV routes

In this paper, we extend spacing of performance based arrivals on converging routes (SPACR) to include a potential use of required time of arrival (RTA) and present an operational concept using it in conjunction with lateral offsets and converging runway display aid (CRDA). We present analytic results related to ground computation of RTA and matching that with the airborne computation. Results of human-in-the-loop experiments related to using SPACR to manage the final merge using only CRDA are reported.

Potential benefits of a Paired Approach procedure to closely spaced parallel runways in instrument and marginal visual conditions

This paper discusses a concept called ldquopaired approachesrdquo which is designed to facilitate approaches to closely spaced parallel runways (CSPRs) - i.e., runways separated by 700 ft to 2500 ft, in instrument meteorological conditions (IMC). Such runway pairs experience a significant loss of arrival capacity during IMC and marginal visual conditions because currently, runway pairs like this can only be used for simultaneous arrivals when pilots can provide visual separation. The basic procedure design, operations concept, the required cockpit tools and initial feasibility of the paired approach concept were developed in the 1990psilas and included real time pilot and controller simulations and evaluations. These initial simulations indicated that the paired approach procedure was feasible for both pilots and controllers. This paper focuses on the potential benefits of the procedure. It first provides a brief review of the procedure and prior work. It discusses the variety of procedures currently available for parallel runways, and discusses the magnitude of the delay problem in the National Airspace System (NAS) not addressed by any of these existing procedures or procedures under development, but which the proposed paired approach procedure would address. It presents the potential capacity gain from the paired approach procedure at two representative major airports, and the percentage of time that the procedure could be available. The paper also presents a brief summary of potential infrastructure requirements for implementing the procedure, and concludes by providing an outline of the research and development needed to establish its deployment in the NAS.

Air ground collaboration through delegated separation: Application for departures and arrivals

Delegated separation is an air traffic management capability in which responsibility for separation from one or more aircraft is assigned to the flight crew by an air traffic controller, in specific tactical situations, to improve operational efficiency in the National Airspace System (NAS). In this human-in-the-loop (HITL) simulation, 8 airline pilots flew departure and arrival scenarios while using a cockpit display of traffic information to maintain separation from a lead airplane. Pilots reported that workload for the departure and arrival tasks was well within acceptable limits and that they would be willing to perform this task with the CDTI as implemented in this study. Objective spacing performance showed reduced spacing compared to the baseline condition where controllers retained separation responsibility. The observed baseline and delegated separation spacing distributions were applied to a fast time simulation to estimate the departure throughput benefit that may result from the application of these procedures. The estimated improvement in arrival rate was about 3 per hour for single runway arrivals, and NN about 4 per hour for single runway departures. Implications for NextGen operational improvement are discussed.

Converging Runway Display Aid in the NAS: Challenges, successes and outlook

The Converging Runway Display Aid (CRDA) is a simple, passive visualization tool that has been available in the terminal automation systems in the National Airspace System (NAS) for about 20 years. CRDA is geared towards simplifying the use of intersecting or converging approaches and paths. Its simplicity has often prompted aviation enthusiasts to hypothesize wider use in the NAS to improve both the safety and capacity of the system. Even so, the tool has not realized wide-spread use in the NAS. Recently, RTCA Task Force V recommended that it be implemented at more sites in the NAS. The Federal Aviation Administration (FAA) has incorporated its wider use as one of its flight plan goals. This has helped its deployment at several new key sites. This paper explores basic factors that contribute to the challenges in deploying CRDA and how they could be addressed. It presents the example of the recent CRDA deployment at Newark Liberty International Airport (EWR) to document and illustrate how this process can and has been applied successfully. It describes the impact of the CRDA use at EWR by analyzing one year of operational data. It concludes with a report on the outlook for CRDA deployment in the NAS.

Management of holding patterns: A potential ADS-B application

Holding in the national airspace system (NAS) is a necessity in the management of air traffic into the major airports in the system. The necessity follows from the desire not to waste any landing slots at the airport in the face of system uncertainties. Holding patterns maintain a ready reservoir of aircraft nearby the airport to provide a steady flow of aircraft. At the same time that this strategy provides an effective mechanism for providing pressure on the airport, it is workload intensive and inefficient in flowing aircraft uniformly to the airport. This document provides evidence of the amount of holding that is experienced for the New York airports and introduces a concept of using automatic dependent surveillance - broadcast (ADS-B) information to reduce the controller workload and increase the uniformity of the flow of aircraft out of the holding patterns. Estimates of the expected benefits are also presented as well as the next steps to be taken.

RNP RNAV Arrival Route Coordination

This paper reports on an examination of the RNP RNAV-based algorithm of the relative position indicator (RPI) of the projected aircraft over a range of expected geometries. First, a simple two segment route projected onto a straight path will be examined. The accuracy and behavior of the projected aircraft indicator depends on route conformance and the geometry of the two route segments, ranging from a fairly benign straight adjoining segments to a challenging 180 degree turn such as a downwind to the base leg of an approach. More complex multi-segmented instances where the waypoints defining the reference route and the RPI route are not collinear will also be analyzed and compared. The simulation tool replicates the views of terminal controllers and will be used to identify any anomalous projected-aircraft behavior

Some New Potential ASAS Applications in the Terminal and En Route Domains

This paper documents new Airborne Separation Assistance System (ASAS) applications for consideration by the ASAS community for further analysis and development. It identifies several potential applications of the information displayed on a cockpit display of traffic information (CDTI) which may substitute for direct visual contact with a particular airplane of interest. CDTI assisted “visual” separation (CAVS) may provide operational efficiency in the terminal area under instrument meteorological conditions (IMC) that could approach that of pure visual operations in visual meteorological conditions (VMC). If proved feasible IMC CAVS applications would provide significant capacity benefits in the terminal domain. Several CAVS applications are presented, including CDTI based spacing during instrument approaches (IMC CAVS) to single and parallel runways and departure spacing during high demand departure operations (Departure CAVS). The document describes the problems associated with holding patterns in the National Airspace System (NAS) and postulates an evolutionary ASAS application of ADS-B based spacing and separation for reducing ATC workload during holding and improving the spacing accuracy out of holding patterns. The paper also includes description of an application of merging and spacing for departures. The proposed applications include a need statement citing examples from current NAS operations, and conclude with a brief application description. It is recommended that these proposals be analyzed in greater detail to determine their NAS-wide benefits and feasibility.

Using real-time aircraft reports of wind and environmental parameters to enable dynamic cockpit-based wake tools

The Federal Aviation Administration (FAA) is implementing the Next Generation Air Transportation System (NextGen) in the U.S. National Airspace System (NAS). The MITRE Corporations Center for Advanced Aviation System Development (MITRE/CAASD) is supporting the FAA in this mission, and conducts research activities that assist the FAA in leveraging emerging aircraft capabilities. A key area of research is evaluating the feasibility of delegating longitudinal (i.e., in-trail) aircraft spacing to pilots even during low visibility conditions. Longitudinal spacing is needed for avoiding collisions but also for wake turbulence avoidance. As longitudinal spacing is delegated to the flight crew, flight deck-based wake tools are needed to support the task. The pilots need to increase their situational awareness not only of the nearby aircraft but of the wakes that these aircraft produce. The current spacing provided by controllers is dictated by conservative assumptions regarding wake turbulence propagation. Wake turbulence is influenced by the characteristics of the aircraft that produced it as well as winds and other atmospheric conditions. This information could conceivably be transmitted by each aircraft as it enters various phases of flight, such as the approach to an airport. A trailing aircraft could then use this information to construct a picture of the probable location of the wake which would increase the pilots situational awareness of the wake. To make a realistic assessment of the location and strength of a wake vortex, real-time weather information needs to be known in the vicinity of the aircraft producing the wake. This paper addresses the quality of that information and how any uncertainty in this information will affect the estimate of the location and strength of wake using current wake dynamics estimating programs that could be used on an aircraft. There are systems currently on aircraft that transmit precisely this information to the ground. In the United States there are several airlines that participate in the Meteorological Data Collection and Reporting System (MDCRS) run by ARINC for the airlines. This data has been archived by the National Oceanic and Atmospheric Administration (NOAA) since 2001. Using this data, we have found that there is uncertainty in wind and other atmospheric parameters, even in the approach phase of flight, over a short span of time. Using these results, we show the uncertainty in the wake positions and discuss the implications for using this information for cockpit visualization tools.

Air ground collaboration through delegated separation: Results of simulations for arrivals to closely spaced parallel runways

Delegated separation is an air traffic management concept in which responsibility for separation from one or more aircraft is assigned to the flight crew by an air traffic controller, in specific tactical situations, to improve operational efficiency in the National Airspace System (NAS). One example of delegated separation that is used in todays Air Traffic Control (ATC) system is visual separation, during which which controllers request that pilots accept responsibility for separation by direct visual contact with another aircraft. Delegated separation procedures using emerging display technology which brings information on nearby traffic to the flight deck have been explored for more than three decades. With the advent of Automatic Dependent Surveillance — Broadcast (ADS-B) and Cockpit Displays of Traffic Information (CDTI) the possibility of using delegated separation procedures, even when other aircraft cannot be seen, is now a practical possibility. In this human-in-the-loop (HITL) simulation, 12 airline pilots flew a series of scenarios to assess the acceptability of delegated separation during closely spaced parallel approaches. The operations concept is that pilots use the information available on a CDTI in a manner that is directly analogous to the use of out-the-window visual contact when visual separation is being used. Range, closure rate and aircraft wake category were displayed, and a method for highlighting the traffic to follow (TTF) was available. Vertical situation information, including lead aircraft altitude history, was provided to support wake avoidance judgments. When pilots were cleared for the instrument approach with delegated separation responsibility, they were free to choose a spacing interval that they judged to be safe. Lead aircraft to follow were Large, Heavy and Boeing 757 aircraft, requiring pilots to consider the possibility of wake encounter in making a separation judgment. Ownship was assumed to be in the Large wake category. The simulated scenarios were instrument approaches to closely spaced parallel runways, performed in marginal visual meteorological conditions with a ceiling of approximately 1200 ft and a visibility of 5 miles. Confederate air traffic controllers provided real-time communications, traffic point out, and control instructions to the pilots. Lead aircraft trajectories were scripted, and their communications were assumed to be on another radio frequency. A confederate pilot performed pilot monitoring duties. The simulated weather conditions precluded actual visual contact with the lead aircraft until breaking out underneath the overcast layer at about 2.5 miles from the runway threshold. Pilots reported that the information available on the CDTI was sufficient to perform the separation task, workload for the arrival task was within acceptable limits, and that they would be willing to perform this task in actual operations with the CDTI as implemented in this study, with respect to Large aircraft as leaders. However, some pilots raised concerns when following lead aircraft for which additional spacing would normally be provided by controllers due to their wake category. Objective spacing performance showed improvement over the baseline case. The observed baseline and delegated separation spacing distributions were applied to a fast-time simulation to estimate the arrival throughput benefits that may result from the application of these procedures. Fast time simulation data for two cases are reported. The first case used observed separation from the simulation for Large leaders and standard separation behind Heavy and Boeing 757 leads. The second case used observed separation for all leaders. Even when restricted to Large leaders, significant benefits were computed compared to the no-delegation condition with a single arrival stream as would be required under the weather conditions simulated.