Formal Analysis of the Operational Concept for the Small Aircraft Transportation System

The Small Aircraft Transportation System (SATS) is a NASA project aimed at increasing access to small non-towered non-radar airports in the US. SATS is a radical new approach to air traffic management where pilots flying instrument flight rules are responsible for separation without air traffic control services. In this paper, the SATS project serves as a case study of an operational air traffic concept that has been designed and analyzed primarily using formal techniques. The SATS concept of operations is modeled using non-deterministic, asynchronous transition systems, which are then formally analyzed using state exploration techniques. The objective of the analysis is to show, in a mathematical framework, that the concept of operation complies with a set of safety requirements such as absence of dead-locks, maintaining aircraft separation, and robustness with respect to the occurrence of off-nominal events. The models also serve as design tools. Indeed, they were used to configure the nominal flight procedures and the geometry of the SATS airspace.