Continuous Descent Arrivals Research Articles

Integration of the ground-based augmentation system in continuous descent operations

Predictability is a necessity in today's commercial flight operations if delays are to be minimized. Possible mitigations, such as the implementation of continuous descent arrivals (CDAs), may help generate the required procedural predictability to curtail these delays. However, on the basis of its individual avionics suite, each aircraft follows a different barometric vertical descent path; furthermore, the aircraft may be given additional level-off segments by air traffic control to compensate for possible deviations in the vertical profile. Therefore, aircraft flying the current descent profiles are too unpredictable and thus the procedures cannot be implemented in complex airspace structures or when traffic is moderate to high. This study introduces a mitigation to this problem by taking the global positioning system (GPS) one step further by integrating the GPS-based ground-based augmentation system (GBAS) into the new optimized continuous decent arrival procedure, subsequently, allowing for the introduction of a geometrical vertical guidance, namely, the GBASCDA, which will make the aircraft flying the descent profile predictable. With the increase in availability of GBAS aircraft equipage, specifically the GPS landing system (GLS), and the approaching amendment of the Appendix E of the Minimum Operational Performance Standards for GPS Local Area Augmentation System Airborne Equipment–RTCA DO-253D, this idea of the integration of the GBAS on the arrival/descent segment as a viable solution may be finally coming within reach.

Optimal Control Based Vertical Trajectory Determination for Continuous Descent Arrival Procedures

Continuous descent arrival (CDA) procedures provide time and fuel savings, and reduce the noise impact of aircraft operations near airports. To date, these procedures have been designed to limit the performance envelopes to achieve trajectory commonality. In this paper, the performance bounds of CDA procedure via multiphase optimal vertical trajectory generation problems with respect to two performance indices—flight time and fuel consumption—have been investigated. The optimal CDA vertical profile is first divided into two segments: the cruise segment before the top of descent (TOD) and the descent segment from the TOD. Then, the second segment is further subdivided based on flap setting and speed constraints. Finally, the resulting multiphase optimal control problem is solved using a pseudospectral method. Two different types of aircraft, B737-500 (light) and B767-400 (heavy), are used in a numerical study, and the optimal CDA trajectories of the two types are compared with a typical vertical navigation (VNAV) CDA trajectory used in CDA applications at several airports. Then, the utility of suboptimal VNAV CDA trajectories that can be created with known flight management system (FMS) VNAV descent modes is explored, and thereby enabling onboard calculation in the FMS via the sensitivity analysis that is performed with various wind conditions.

NextSim: A Portable Human Factors Research Simulator for Future ATC Concepts

In this demonstration, we report on the development of a low fidelity air traffic control simulator that allows researchers to investigate human factors issues related to various NextGen concepts, like flow corridors, continuous descent arrivals, and sky-based separation. NextSim also allows the researcher to collect a number of performance, workload, and situation awareness measures.

Flight Deck-Based Merging and Spacing Operations

The advent of Automatic Dependent Surveillance-Broadcast (ADS-B) has opened up a new realm of precise air-to-air surveillance in which flight crews, when properly supported by automation and procedures, will be able to accept new tasks and function at a level in keeping with far-term strategic goals in air traffic management. In pursuit of that goal, MITRE and NASA are participating in a Federal Aviation Administration (FAA)-sponsored group that is developing and testing an early airborne spacing application called Flight Deck-based Merging and Spacing (FDMS). Several human-in-the-loop and Monte Carlo simulations have validated the ability of an aircraft to space itself precisely relative to another aircraft during continuous descent arrivals (CDA). Results indicate that FDMS is viable and that expected benefits should be realized. A limited implementation of FDMS is currently certified and in use in revenue flights by UPS. This is the first fielding of an airborne spacing concept.

Flight-Test Evaluation of the Tool for Analysis of Separation and Throughput

The tool for analysis of separation and throughput has been developed to predict the range of possible trajectories of aircraft performing any given continuous descent arrival and thereby determine the minimum target spacing at a metering point, such that there is a high probability of no separation violations thereafter. The resulting reduced need for controller intervention is expected to facilitate the implementation of continuous descent arrival. This tool includes a fast-time Monte Carlo trajectory simulator and a theoretically rigorous separation analysis methodology based on the probabilistic characteristics of trajectories. The tool was used to determine the target spacing for a continuous descent arrival flight test conducted in September 2004 at Louisville International Airport. Results of the flight test indicate that the 15-n-mile target spacing yielded a conditional probability of 69.6% for the continuous descent arrival to runway 35L, very close to the predicted value of 68.6%; and an overall total probability of 81.7%, which is between the predicted values of 79.6% and 85.0 % for the continuous descent arrival to runway 35L and 17R, respectively. The flight test demonstrated that, by using the tool as developed, continuous descent arrival can be efficiently implemented under moderate to moderately high traffic conditions, thereby achieving much needed environmental and economic benefits.