Use of Traffic Intent Information by Autonomous Aircraft in Constrained Operations

This paper presents findings of a research study designed to provide insight into the issue of intent information exchange in constrained en-route air-traffic operations and its effect on pilot decision-making and flight performance. The piloted simulation was conducted in the Air Traffic Operations Laboratory at the NASA Langley Research Center. Two operational modes for autonomous flight management were compared under conditions of low and high operational complexity (traffic and airspace hazard density). The tactical mode was characterized primarily by the use of traffic state data for conflict detection and resolution and a manual approach to meeting operational constraints. The strategic mode involved the combined use of traffic state and intent information, provided the pilot an additional level of alerting, and allowed an automated approach to meeting operational constraints. Operational constraints applied in the experiment included separation assurance, schedule adherence, airspace hazard avoidance, flight efficiency, and passenger comfort. The strategic operational mode was found to be effective in reducing unnecessary maneuvering in conflict situations where the intruder's intended maneuvers would resolve the conflict. Conditions of high operational complexity and vertical maneuvering resulted in increased proliferation of conflicts, but both operational modes exhibited characteristics of stability based on observed conflict proliferation rates of less than 30 percent. Scenario case studies illustrated the need for maneuver flight restrictions to prevent the creation of new conflicts through maneuvering and the need for an improved user interface design that appropriately focuses the pilot's attention on conflict prevention information. Pilot real-time assessment of maximum workload indicated minimal sensitivity to operational complexity, providing further evidence that pilot workload is not the limiting factor for feasibility of an en-route distributed traffic management system, even under highly constrained conditions. * Member, AIAA Introduction A significant research activity within the NASA Advanced Air Transportation Technologies project is focused upon far-term operations of the National Airspace System (NAS). A general description of the activity is Distributed Air/Ground Traffic Management (DAG-TM). NASA has developed a high-level concept of operations for DAG-TM consisting of 15 elements spanning gate-to-gate operations 1. One particular concept element, developed to address the en-route flight regime, 2 has the potential to increase capacity, flexibility, and robustness of the NAS by distributing responsibility for (1) separation assurance, and (2) conformance with local traffic flow management (TFM) constraints between airborne and ground-based systems. In this concept element, pilots of aircraft designated as "autonomous" have the authority to generate and implement new trajectories at their discretion in order to meet individual, company (if applicable), and/or system-level goals. With this authority for autonomous operations comes the responsibility for separation assurance and compliance with local TFM constraints established by the groundbased air traffic service provider (ATSP). Aircraft not operating as autonomous aircraft are designated as "managed aircraft," and similar to current operations, their flight crews comply with clearances provided by the ATSP, who maintains responsibility for their separation assurance and flow management conformance.