Gunnar Schwoch

Designing freedom into trajectory-based operations

Modern flight management systems (FMS) are able to predict highly precise 4D trajectories for complete flights from take-off to touchdown. The generated trajectories take into account aircraft’s performance parameters, altitude-, speed- and time constraints, given procedures, and the expected weather conditions, as forecasted. Based on these trajectories, a traffic scheduler can generate and guarantee conflict-free traffic—as long as every aircraft sticks to the plan. However, even the most accurate trajectory becomes unrealizable when significant disturbances arise that were not foreseeable at prediction time. Uncertainties like imprecise weather forecasts, inaccurate departure times, and issues with delayed passengers influence a direct implementation of pre-planned 4D schedules in practice. If such disturbing events are rare, the overall plan may be adapted. Too many disturbances might ruin the whole schedule though. In the initial planning stage, larger margins increase overall robustness, but obviously also downgrade the possible optimum of the whole system. This article therefore discusses the trade-off between built-in robustness and efficiency. Resilience is added by increasing the separation between trajectories. Assuming that the mandatory distance for guaranteeing safe operations remains constant, the additional separation provides freedom for aircraft following their trajectories.

Global time-based conflict solution: Towards the overall optimum

The goal of future Air Traffic Management (ATM) is simple: every airborne vehicle shall fly as efficient as possible while keeping safety and other key performance areas high. 4D-Trajectory-Based Operations (TBO) promise improved efficiency, safety benefits, and high predictability in advance. Highly accurate 4D-trajectories allow early conflict detection and efficient conflict resolution. Independently predicted 4D-trajectories ensuring highest efficiency for everyone create conflicts already with low traffic densities. These conflicts are usually solved by lateral, vertical, or time-based avoidance. This paper is about time-based conflict avoidance in its most efficient way. Flight duration is kept constant allowing the aircraft to fly its preferred optimum profile. Adjustments are done on whole flights by shifting them by some minutes in time. The paper presents results from conflict resolution on an ECAC wide traffic scenario holding 33k aircraft with 29k initial conflicts. The idea is to de-conflict the busiest day above Europe 2011 in its most efficient way.

Curved approaches and airborne spacing for efficient closely spaced parallel runway operations in IMC

In this contribution the existing RPAT concept for simultaneous approaches to closely spaced parallel runways is further elaborated to be implemented in low visibility. Besides RNP capabilities this concept uses as well ASAS spacing capabilities. The basic procedure design aspects and the required airborne functions are described. The airborne spacing will first be initiated by a 4D approach in which the trajectory of the target aircraft is being predicted based on position information provided by ADS-B or TIS-B. The ASPA function itself is then used to adjust the spacing such that after the S-curve the RPAT aircraft is parallel or slightly behind the target aircraft. Further on, results from simulations trails and initial flight trials will be presented. It is foreseen to fully flight test this concept in fall/winter 2010 at Braunschweig airport.

Integrating RPAS - published approach procedures vs. local arrangements

This paper presents the setup, the assessment methods, and the results of a flight trial that was conducted in June 2016 in order to demonstrate integration of remotely piloted aircraft systems (RPAS) into the current airspace, while also acknowledging that there are challenges to overcome. An RPAS demonstrator received a flight plan from the ground control station (GCS) using a ground-based data link, departing from Braunschweig-Wolfsburg airport and flying towards Leipzig/Halle airport on published routing. When approaching Leipzig/Halle airport, the data link was lost as predicted, and the arrival procedure was altered by air traffic control (ATC), which showed that an additional and dedicated RPAS controller at arrival airports might be valuable and advantageous. Focus of this paper is the description of the components that were used during the trial and their interconnectivity, the evaluation of quantitative recorded data and the qualitative experienced difficulties and challenges. Assessment of the recorded data is divided into data link quality, data link latency, and flight following performance (vertical and lateral following accuracy), with the latter being linked to existing performance based navigation (PBN) parameters by ICAO and height-keeping performance values by EASA. The paper concludes with a discussion on the investigated integration concept.

Optimization without limits — The world wide air traffic management project

In air traffic management, optimization is often restricted to local areas, e.g., to the vicinity of airports. Procedures around these areas stay unchanged, and effects from optimizations concerning ecological efficiency are not considered adequately. Investigating new concepts, this typically results in local gain of efficiency without proving the global benefit. The project World Wide Air Traffic Management (WW-ATM) creates a platform for optimization and validation of world-wide concepts considering feasibility, throughput, costs-and ecological efficiency, and robustness respectively fault liability. Based on different evaluation and optimization tools, complete traffic scenarios can be analyzed and improved both strategically and tactically.

Enhancing unmanned flight operations in crisis management with live aerial images

This paper presents the design and execution of a flight experiment in 2015, which was designed to investigate new technologies for crisis management by using a remotely piloted aircraft system (RPAS) demonstrator for airborne image collection. Based on an assumed crisis scenario, which simulates a severe flooding that caused road damages and enclosed people in water, several aspects of crisis management were tested and validated. Aerial images were collected and sent to the ground in two flight phases with different objectives. The focus of this paper is to present the technical set-up of the experiment and involved systems, an overview of different scan and search patterns, the realization of flight plans using these patterns, and the actual execution of the experiment in two phases. Examples for the usage of live images in ground systems are presented. The contribution of such a system to crisis management is discussed, and current legal limitations are taken into account. An overview of upcoming experiments and developments of the involved systems is given.

Individualism in global airspace-user-preferred trajectories in future ATM

Both future air traffic management programs SESAR and NextGen foresee trajectory based operations as one of the major enablers for more efficient handling of air traffic. Furthermore, both initiatives claim to support user preferred trajectories. However, using a common airspace it is unlikely to get a conflict-free scenario from independently optimized trajectories. This paper investigates if the concept of user-preferred trajectories is feasible, and what constraints are necessary to reach a conflict-free global scenario based on independently optimized trajectories. Based on a traffic scenario with ~33k individually optimized trajectories yielding ~29k conflicts, a strategic resolution is performed generating least possible penalties for involved aircraft. The main technique for solving conflicts is shifting whole flights in time by a few minutes. Direct and recursive algorithms are presented; a focus is put on solving airport-related conflicts first. More than 94% of all conflicts can be solved by shifting whole flights in time respecting a maximum offset of 10 minutes.