Harry N. Swenson

Efficiency Benefits Using the Terminal Area Precision Scheduling and Spacing System

NASA has developed a capability for terminal area precision scheduling and spacing (TAPSS) to increase the use of fuel-efficient arrival procedures during periods of traffic congestion at a high-density airport. Sustained use of fuel-efficient procedures throughout the entire arrival phase of flight reduces overall fuel burn, greenhouse gas emissions and noise pollution. The TAPSS system is a 4D trajectory-based strategic planning and control tool that computes schedules and sequences for arrivals to facilitate optimal profile descents. This paper focuses on quantifying the efficiency benefits associated with using the TAPSS system, measured by reduction of level segments during aircraft descent and flight distance and time savings. The TAPSS system was tested in a series of human-in-the-loop simulations and compared to current procedures. Compared to the current use of the TMA system, simulation results indicate a reduction of total level segment distance by 50% and flight distance and time savings by 7% in the arrival portion of flight (~200 nm from the airport). The TAPSS system resulted in aircraft maintaining continuous descent operations longer and with more precision, both achieved under heavy traffic demand levels.

CHALLENGES OF FIELD TESTING THE TRAFFIC MANAGEMENT ADVISOR (TMA) IN AN OPERATIONAL AIR TRAFFIC CONTROL FACILITY

The Traffic Management Advisor (TMA), the sequence and schedule tool of the Center/TRACON Automation System (CTAS), was evaluated at the Fort Worth Center in the summer of 1996. This paper describes the challenges encountered during the various phases of the TMA field evaluation, which included system installation, personnel training, and data collection. Operational procedures were developed and applied to the evaluation process that would ensure air safety. The five weeks of field evaluation imposed minimal impact on the hosting facility and provided valuable engineering and human factors data. The collection of data was very much an opportunistic affair, due to dynamic traffic conditions. One measure of the success of the TMA evaluation is that, rather than remove TMA after the evaluation until it could be fully implemented, the prototype TMA is in continual use at ZFW as fully operational version is readied for implementation.

Evaluation of the Terminal Sequencing and Spacing system for Performance-Based Navigation arrivals

NASA has developed the Terminal Sequencing and Spacing (TSS) system, a suite of advanced arrival management technologies combining time-based scheduling and controller precision spacing tools. TSS is a ground-based controller automation tool that facilitates sequencing and merging arrivals that have both current standard ATC routes and terminal Performance-Based Navigation (PBN) routes, especially during highly congested demand periods. In collaboration with the FAA and MITREs Center for Advanced Aviation System Development (CAASD), TSS system performance was evaluated in human-in-the-loop (HITL) simulations with currently active controllers as participants. Traffic scenarios had mixed Area Navigation (RNAV) and Required Navigation Performance (RNP) equipage, where the more advanced RNP-equipped aircraft had preferential treatment with a shorter approach option. Simulation results indicate the TSS system achieved benefits by enabling PBN, while maintaining high throughput rates-10% above baseline demand levels. Flight path predictability improved, where path deviation was reduced by 2 NM on average and variance in the downwind leg length was 75% less. Arrivals flew more fuel-efficient descents for longer, spending an average of 39 seconds less in step-down level altitude segments. Self-reported controller workload was reduced, with statistically significant differences at the p<;0.01 level. The RNP-equipped arrivals were also able to more frequently capitalize on the benefits of being “Best-Equipped, Best-Served” (BEBS), where less vectoring was needed and nearly all RNP approaches were conducted without interruption.

NASA's ATM technology demonstration 1 (ATD-1): Integrated concept of arrival operations

This paper describes operations and procedures envisioned for NASAs Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1). The ATD-1 Concept of Operations (ConOps) demonstration will integrate three NASA technologies to achieve high throughput, fuel-efficient arrival operations into busy terminal airspace. They are Traffic Management Advisor with Terminal Metering (TMA-TM) for precise time-based schedules to the runway and points within the terminal area, Controller-Managed Spacing (CMS) decision support tools for terminal controllers to better manage aircraft delay using speed control, and Flight deck Interval Management (FIM) avionics and flight crew procedures to conduct airborne spacing operations. The ATD-1 concept provides de-conflicted and efficient operations of multiple arrival streams of aircraft, passing through multiple merge points, from top-of-descent (TOD) to touchdown. It also enables aircraft to conduct Optimized Profile Descents (OPDs) from en route altitude to the runway, using primarily speed control to maintain separation and schedule. The ATD-1 project is currently addressing the challenges of integrating the three technologies, and implantation into an operational environment. Goals of the ATD-1 demonstration include increasing the throughput of high-density airports, reducing controller workload, increasing efficiency of arrival operations and the frequency of trajectory-based operations, and promoting aircraft ADS-B equipage.

Simulation evaluation of a low-altitude helicopter flight guidance system adapted for a helmet-mounted display

A computer aiding concept for low-altitude helicopter flight has been developed and evaluated in a real-time piloted simulation. The concept included an optimal control trajectory-generation algorithm based upon dynamic programming, and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The pilot evaluation was conducted at the NASA-Ames Research Center moving base vertical motion simulator by pilots representing NASA, the US Army, Air Force, and helicopter industry. The pilot manually tracked the trajectory generated by the algorithm utilizing the HMD symbology. The pilots were able to perform the tracking tasks satisfactorily while maintaining a high degree of awareness of the outside world.<<ETX>>

Development and evaluation of the terminal precision scheduling and spacing system for off-nominal condition operations

NASA has developed a capability for terminal area precision scheduling and spacing (TAPSS) to increase airport throughput and the use of fuel-efficient arrival procedures during periods of peak traffic congestion at high-throughput airports. This advanced technology represents NASAs current concept for the NextGen terminal metering desired capability. A series of high-fidelity human-in-the-loop simulation experiments were conducted to evaluate the performance of the TAPSS system during off-nominal conditions, specifically aircraft executing missed-approach and go-around procedures after transitioning to the final approach fix during an attempted landing. Each simulation run contained 2-4 missed approaches during a highly congested 60-minute period. The TAPSS system was adapted to arrival operations for the Los Angeles International airport (LAX). It was also enhanced to support automated missed-approach processing and procedures. The experiments evaluated the utility of the missed approach enhanced automation features by comparing system performance and controller workload with and without the enhancements. The simulated traffic throughput exceeded that of the current LAX operations with two runways in instrument meteorological conditions (IMC) by 10%. The results showed that when using the enhanced automation, the controllers could maintain the higher throughput levels with more consistent and predictable routing in the final operations but with increased vectoring and off-route aircraft in the feeder positions. Controller workload results indicated a preference for the automation enhancement especially as the numbers of missed approaches increased from 2 to 4 during the 60-minute evaluation period.

Optimal time advance in terminal area arrivals: Throughput vs. fuel savings

The current operational practice in scheduling air traffic arriving at an airport is to adjust flight schedules by delay, i.e. a postponement of an aircrafts arrival at a scheduled location, to manage safely the FAA-mandated separation constraints between aircraft. To meet the observed and forecast growth in traffic demand, however, the practice of time advance (speeding up an aircraft toward a scheduled location) is envisioned for future operations as a practice additional to delay. Time advance has two potential advantages. The first is the capability to minimize, or at least reduce, the excess separation (the distances between pairs of aircraft immediately in-trail) and thereby to increase the throughput of the arriving traffic. The second is to reduce the total traffic delay when the traffic sample is below saturation density. A cost associated with time advance is the fuel expenditure required by an aircraft to speed up. We present an optimal control model of air traffic arriving in a terminal area and solve it using the Pontryagin Maximum Principle. The admissible controls allow time advance, as well as delay, some of the way. The cost function reflects the trade-off between minimizing two competing objectives: excess separation (negatively correlated with throughput) and fuel burn. A number of instances are solved using three different methods, to demonstrate consistency of solutions.

Evaluation of the Terminal Area Precision Scheduling and Spacing system for Performance-Based Navigation arrivals

In 2012, NASA and FAA jointly conducted a human-in-the-loop air traffic simulation to evaluate the utility of the Terminal Area Precision Scheduling and Spacing (TAPSS) system for supporting Performance-Based Navigation arrival operations during periods of congestion at a mid-sized airport. The TAPSS system is a trajectory-based strategic planning and tactical control tool that was developed to efficiently manage arrivals. For this study, the TAPSS system was enhanced to handle Required Navigation Performance arrivals. A baseline case, where none of the TAPSS systems advisories were provided, was run along with two different configurations of the TAPSS system with differing sets of controller advisory tools. The engineering data indicate that the TAPSS system has a potential to enable efficient Performance-Based Navigation arrival operations. The participating controllers found the TAPSS systems advisories useful. When controllers were given the full set of TAPSS advisory tools, 90% of Required Navigation Performance arrivals stayed on-path as compared to 87% in the baseline case, the average extra track distance of Area Navigation arrivals decreased by 36%, and the average number of controller voice communications decreased by 13%.

Simulation development of a forward sensor-enhanced low-altitude guidance system

The requirement to operate aircraft at low-altitude near the terrain is common in the military community and essential for helicopters. The risk and crew workload in this flight regime is severe, with navigation, guidance, and obstacle avoidance demanding high attention, A guidance system relying on digitized terrain elevation maps has been developed that employs airborne navigation, mission requirements, aircraft performance limits, and radar altimeter returns to generate a valley-seeking, low-altitude trajectory between waypoints for display to the pilot. This system has been flight demonstrated to 150 ft above ground level attitude, and is primarily limited by the ability of the pilot to perform obstacle detection and avoidance. In this study, a wide field of view forward sensor has been modeled and incorporated in the guidance system for the purpose of relieving the pilot of the obstacle avoidance duty. The results of a piloted, motion-based simulation of this enhanced low-altitude guidance system is presented. Simulated flights to 50 ft altitude in the presence of obstacles were demonstrated while maintaining situational awareness and close tracking of the guidance trajectory.<<ETX>>

NextGen Technologies on the FAA's Standard Terminal Automation Replacement System

This paper describes the integration, evaluation, and results from a high-fidelity human-in-the-loop (HITL) simulation of key NASA Air Traffic Management Technology Demonstration - 1 (ATD-1) technologies implemented in an enhanced version of the FAAs Standard Terminal Automation Replacement System (STARS) platform. These ATD-1 technologies include: (1) a NASA enhanced version of the FAAs Time-Based Flow Management, (2) a NASA ground-based automation technology known as controller-managed spacing (CMS), and (3) a NASA advanced avionics airborne technology known as flight-deck interval-management (FIM). These ATD-1 technologies have been extensively tested in large-scale HITL simulations using general-purpose workstations to study air transportation technologies. These general-purpose workstations perform multiple functions and are collectively referred to as the Multi-Aircraft Control System (MACS). Researchers at NASA Ames Research Center and Raytheon collaborated to augment the STARS platform by including CMS and FIM advisory tools to validate the feasibility of integrating these automation enhancements into the current FAA automation infrastructure. NASA Ames acquired three STARS terminal controller workstations, and then integrated the ATD-1 technologies. HITL simulations were conducted to evaluate the ATD-1 technologies when using the STARS platform. These results were compared with the results obtained when the ATD-1 technologies were tested in the MACS environment. Results collected from the numerical data show acceptably minor differences, and, together with the subjective controller questionnaires showing a trend towards preferring STARS, validate the ATD-1/STARS integration.