Feature article: proof-of-concept airborne sense and avoid system with ACAS-X U flight test

Today, unmanned aircraft system (UAS) operations are typically conducted in segregated airspace and in limited combat theaters. In order to integrate UAS into the National Airspace System (NAS), UAS must operate safely, efficiently, and be compatible with existing manned aircraft traffic so that the overall safety and efficiency of the airspace is not degraded [1]. There are many challenges that lie ahead to allow UAS unrestricted access to NAS, but perhaps the greatest technical challenge involves fulfilling the "See and Avoid" requirements (14CFR 91.111 and 91.113).