Joel Kenneth Klooster

Trajectory Synchronization between air and ground trajectory predictors

Trajectory Based Operations is a key concept of future air traffic management systems in both the United States and Europe. An overarching goal of Trajectory Based Operations is to reduce the uncertainty associated with the prediction of an aircrafts future location through the use of an accurate 4-Dimensional Trajectory. This is not realizable without improving the coordination and interoperability of air and ground systems. By leveraging GEs Flight Management System and aircraft expertise with Lockheed Martins Air Traffic Control domain expertise including the En Route Automation Modernization system, a research effort has been undertaken to explore and evaluate Trajectory Synchronization and Negotiation concepts that bring airspace operations closer to the business-optimal goal in a safe and efficient manner. This paper focuses on different aspects of Trajectory Synchronization concepts, including existing gaps and shortfalls, and potential approaches to resolve them. An analysis of trajectory synchronization use cases and an air-ground trajectory synchronization algorithm are presented. The simulation infrastructure incorporating actual Flight Management System and En Route Automation Modernization system trajectory predictors is discussed, including simulation results from a trajectory synchronization case study. The cases studied show that consistent trajectory predictions can be achieved between the air and ground systems through trajectory data exchange via Controller-Pilot Data Link Communications uplink and downlink messages as well as the Automatic Dependent Surveillance-Contract service, including the Extended Projected Profile application.

Seattle required time of arrival (RTA) flight trials

The Federal Aviation Administration (FAA) conducted limited operational flight trials of Trajectory Based Operations (TBO) based upon the use of the Required Time-of-Arrival (RTA) function in modern Flight Management Systems (FMSs) October 25‣31, 2010. The flight trials were conducted on the Olympia Six (OLM6) Standard Terminal Arrival (STAR) for the Seattle-Tacoma International Airport by select Alaska Airlines pilots flying Boeing 737 Next Generation (B737NG) aircraft. The operational concept was the assignment of the Scheduled Time-of-Arrival (STA) from the Traffic Management Advisor (TMA) flow management tool as the RTA for aircraft to meet with improved delivery accuracy. In the trials, many aircraft successfully met assigned crossing times at OLM fix using the RTA function of their advanced FMS allowing fuel-efficient descents. This paper describes the results of the flight trial, indicating that the current generation of B737NG avionics can meet meter fix times generated by TMA within 20 seconds while honoring air traffic control (ATC) restrictions of speed and altitude given appropriate FMS configurations.

Towards an open test bed for the study of trajectory synchronization in the future ATM system: The ASIS initiative

The new ATM concepts proposed by both SESAR and Next Gen require a paradigm shift from an often uncoordinated system that relies on centralized, ground-based tactical separation assurance to an integrated and coordinated one centered on strategic, collaborative trajectory management. Thus, in the future European ATM system defined by SESAR, the aircraft Business Trajectory will become the centerpiece of a new set of operating procedures collectively referred to as Trajectory-Based Operations (TBO). The implementation of TBO will require that the human actors in the ATM system rely on advanced decision-support tools (DSTs) that will enhance both airborne and ground-based automation systems, allowing closer adherence to the aircrafts optimal trajectory. Since many of these DSTs will need to operate with a strategic view of the aircrafts intended trajectory, they will require a Trajectory Predictor (TP) to carry out their functions. However, different DSTs may in principle rely on different TPs, which may produce inconsistent trajectories for the same flight, as well as inconsistencies with the aircraft generated trajectory (the trajectory generated by the Flight Management System). This lack of consistency among predictions is seen as a key issue affecting the integration and harmonized operation of current and future DSTs. Coordination between TPs is key to ensure coordination between DSTs and hence the successful evolution and implementation of TBO.

Air-ground trajectory synchronization — Metrics and simulation results

It has been established that Trajectory Based Operations are a key component of future Air Traffic Management systems as currently underway in the United States with NextGen and Europe with SESAR. One of the major goals of Trajectory Based Operations is to provide participants accurate 4-Dimensional Trajectories predicting the future location of the aircraft with a high level of certainty. This is not realizable without improving the coordination and interoperability of air and ground systems. By leveraging GEs Flight Management System and aircraft expertise with Lockheed Martins Air Traffic Control domain expertise, including the En Route Automation Modernization system, a research initiative has been formed to explore and evaluate means of better integrating air and ground systems to bring airspace operations closer to the business-optimal goal in a safe and efficient manner. The two main components of this effort are trajectory synchronization and trajectory negotiation. Trajectory synchronization will essentially result in a more complete flight plan in the air and a more accurate trajectory representation on the ground, which is a prerequisite for trajectory negotiation. This paper briefly discusses the high-level trajectory synchronization algorithm and its implementation in a fast-time simulation environment that incorporates actual Flight Management and Air Traffic Control software. It then focuses on the analysis of metrics and simulation results from several case studies. The conclusion of these studies shows that implementation of the trajectory synchronization algorithm using Controller-Pilot Data Link Communications messages as well as the Automatic Dependent Surveillance-Contract service (including the Extended Projected Profile application) achieves consistent trajectory predictions between the air and ground systems.

Trajectory management driven by user preferences

The evolution of the Traffic Flow Management (TFM) and Air Traffic Control (ATC) systems towards Trajectory Based Operations (TBO) is constrained by the need to support a mixed fleet of aircraft for the foreseeable future. Trajectory synchronization and negotiation in particular are key enablers of TBO that need to take into account both the advanced capabilities in existing and future Flight Management Systems (FMS), and the limitations in performance and capabilities of legacy aircraft. Trajectory management systems will have to address the challenges imposed by this reality. Lockheed Martin and General Electric (GE) have established a Joint Strategic Research Initiative (JSRI) to develop technologies that can efficiently address the challenges of trajectory management. In this paper, we describe a user preference driven trajectory management concept that was developed under the JSRI. The idea consists of providing flight-specific cost information to Decision Support Tools (DST) used by controllers for strategic conflict resolution and schedule management. The cost of operating a flight may be decomposed into the cost of fuel and other direct and time related costs (such as crew pay, aircraft maintenance, or connecting passengers). In current operations, there is no practical mechanism to make this information known to the ground automation (or the controller) which needs to make changes to the business trajectory; moreover, much of this information is considered proprietary or sensitive by the operators, making it difficult or impossible to determine the true cost impact of modifications to the reference business trajectory. However, it is precisely the overall cost of operations that should be driving the decision process. A mechanism has been developed to extract the effective operating cost from the FMS and to make that information available to ground DSTs. Cost information is encoded in coefficients that do not reveal operator specific business strategies that may be considered proprietary. This enables the ground controller (and DSTs) to make an informed decision that may increase the likelihood of operators business objectives being accommodated, and would allow operators to better inform ATCs decisions such that the impact on the business objectives are minimized when changes are required. The encoding of cost information is made in a compact way so that communication band-width requirements are reasonable.