Alexander Kuenz

4D FMS for Increasing Efficiency of TMA Operations

In order to meet the anticipated future demand for air travel, DLRs Institute of Flight Guidance is investigating distributed air-ground traffic management (DAG-TM) for arrivals in the extended TMA. Based on the exchange of information between aircraft and ATC via data link, a trajectory based traffic management can take into account user preferred trajectories as well as make use of highly accurate prediction of aircraft movements. This contribution focuses on the airborne part - in particular on the 4D FMS functions for planning and flying various types of CDA approaches. The planning functions to compute approach profiles ranging from 2 degree (clean configuration) up to steep slopes (more than 5 degree) with early configuration and glide path intersection from above are presented. Furthermore, functions to compensate deviations due to inaccurately forecasted wind are described. These functions ensure flying the predicted flight path. The new CDA functionalities have been implemented in DLRs 4D capable advanced flight management system (AFMS) and intensively tested during various flight trials in the A330 full flight simulator in Berlin and with DLRs test aircraft ATTAS, a VFW 614 twin engine jet transport aircraft modified for research purposes. The results of these trials are presented and discussed

Green trajectories in high traffic TMAs

New conflicting future demands in air travel like gain of capacity and coexistent reduction of environmental impact necessitate new airborne functions and a better integration of these capabilities in air traffic management (ATM). DLRs Advanced Flight Management System proved a highly accurate predictability of 4D trajectories in flight trials with the A330-300 Full Flight Simulator of ZFB Berlin and DLRs test aircraft ATTAS, a VFW 614 twin engine jet transport aircraft modified for research purposes. Due to an inefficient air-ground integration current terminal manoeuvring area (TMA) concepts do not support 4D-capable aircraft in flying fuel efficient and noise abating profiles. A trajectory based TMA handling is necessary to combine aircraft optimized flight profiles with high airport efficiency. This paper presents results of advanced continuous descent approaches (CDA) flight trials with the research aircraft ATTAS and simulation trials with the A330 full flight simulator. Furthermore, a trajectory based TMA concept is introduced as a possible solution for the current trade-off between green trajectories and high airport capacity even in high traffic situations.

Tiling the world — Efficient 4D conflict detection for large scale scenarios

Today, 4D-Trajectory-Based Operations and international harmonization for global Air Traffic Management (ATM) systems are the main driving concept elements for the modernization of ATM. The availability of ground-based 4D trajectories leads to new possibilities allowing early conflict detection and efficient conflict avoidance. Nevertheless, efficient conflict detection becomes a big challenge when dealing with large amounts of detailed trajectories in a global environment. This paper proposes a new representation of 4D trajectories facilitating a high performance conflict detection algorithm. The proposed algorithm subdivides the initial envelope of all trajectories in smaller 4D tiles until each tile contains only one trajectory. If that is not possible before reaching a predefined minimum tile size, a conflict is detected. Since the algorithms runtime is only marginally influenced by the scenarios complexity, this technique is particularly efficient for large scale scenarios.

A global airspace model for 4D-rajectory-based operations

Performing the paradigm shift to 4D-Trajectory-Based Operations will involve several procedural improvements. High planning predictability allows better usage of airspace and dropping some of todays constraining factors. Efficiency improves by flying aircraft specific optimized procedures. By usage of sophisticated models and planning algorithms, total systems performance will come close to global optimum. This paper describes a new and powerful way of modeling 4D airspace incorporating traffic, weather, restricted areas and any other objects existing/moving in 4D airspace. The model represents these objects in a way allowing very fast conflict detection and resolution in order to find a feasible and efficient global solution.

Enabling green profiles for today's traffic mixture in high density

Today, the usage of highly efficient flight procedures often lacks on the missing integration between air and ground based tools. Typically, modifications on both airborne and ground side are necessary to fully benefit from new technologies. Modifications are usually expensive and therefore only implemented if the counterpart also invests in the corresponding work.

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.

Visual assistance to support late merging operations in 4D trajectory-based arrival management

Within the German Aerospace Center (DLR) project FAGI (Future Air Ground Integration), new operational concepts and automation support systems for fuel- and noise-efficient arrival management are being developed. An essential element of the FAGI concept is a modified airspace and route structure, featuring the late merging of different arrival routes to support user-preferred flight profiles such as Continuous Descent Approaches (CDA). The present paper studies aircraft ghosting solutions on the radar display as a potential means to support controllers with merging different streams of aircraft with sufficient precision. In addition to a technical presentation of different ghosting principles, the results of two human in the loop studies are reported. Using objective and subjective data on performance, workload, situation awareness, and eye-tracking analysis, the benefits, trade-offs and acceptance of the visual assistance functions are discussed.

The 5 th dimension in conflict management - XYZT + capability

This article consists of a collection of slides from the authors conference presentation.

Green approaches without trade-off: Final results from the FAGI-project

A fundamental contribution to satisfying future demands in air transport like gain of capacity, reduction of environmental impact, improved flight efficiency and high predictability is often the term “4D”. However, having a look at todays fleet only one out of nine aircraft is currently able to, e.g., fulfill a requested time of arrival with high accuracy. Therefore, a successful transition to a 4D-trajectory based operations strongly depends on how especially the unequipped aircraft without an onboard flight management system fit into the concept. In 2007–2009, the FAGI (Future Air Ground Integration) project investigated a new concept facilitating the transition to 4D-trajectory based air traffic management operations.