Collaborative Situational Awareness for Conflict-Aware Flight Planning

In autonomous air-traffic management scenarios of the future, manned and unmanned aircraft will be able to safely navigate through the National Airspace System, independent of centralized air-traffic controllers. They will do this by sharing critical data necessary for maintaining standard separation with each other. Under such conditions, every aircraft must have sufficient knowledge about other aircraft sharing the airspace to operate safely. In this paper, we specify a safe state of knowledge that is necessary for aircraft to operate safely in the absence of a centralized air-traffic controller and present a distributed knowledge propagation protocol to attain this safe state. This protocol can be used by network-connected aircraft to achieve collaborative situational awareness for cooperative flight planning. We identify certain system conditions necessary to guarantee two correctness properties for our protocol – safety and progress. We use the TLA+ Specification Language to formally specify our protocol, the correctness properties, and the conditions necessary to guarantee the properties. Using the formal specifications, we also provide mechanically-verified proofs of the correctness properties in the TLA+ Proof System.