Alerting logic for multi-mode conflict detection and prevention in autonomous aircraft operations

NASA is developing a concept for far-term implementation of free flight in en-route airspace. The research concept introduces a new category of flight operations - autonomous flight rules (AFR). Properly trained flight crews of AFR-equipped aircraft possess the authority to autonomously plan and execute their preferred 4D trajectories, provided they accept responsibility for maintaining separation from traffic and conforming to ground-uplinked traffic flow management (TFM) constraints. Flight crews are supported in performing these tasks by decision-support automation integrated into the flight deck. Researchers at NASA Langley Research Center are developing a prototype of this decision-support system, called the autonomous operations planner (AOP). Since modern flight decks offer crews several levels of guidance automation, AOP employs multiple representations of the crew´s intentions for conflict detection. In order to be easy to use, responsive to crew-selected guidance options, and supportive of crew-initiated path planning, AOP must prioritize the different forms of intent and associated conflicts, and present the crew with an integrated yet intuitive picture of the current conflict situation. This paper describes the development of an alerting scheme that achieves these goals while meeting concept requirements for alerting time-horizons and the prevention of conflict proliferation. The alerting logic has been implemented in the Air Traffic Operations Laboratory at NASA Langley Research Center, and enables AOP to provide crews with appropriate alerting information when they operate their aircraft in any combination of guidance modes.