Figure 1. The FT&E campaign consisted of a number of head-on encounters between a ScanEagle unmanned aircraft, which carried the SAA system, and a manned Cessna 172. All encounters were coordinated between the participants using very high frequency (VHF) voice radio communication. The ScanEagle was controlled by the remote pilot from its ground control station (GCS) using a custom data link. Power to the SAA system was controlled from the SAA terminal, which was located within the GCS. The SAA terminal also received detection and status information from the SAA system. The SAA system was operated from the SAA system control terminal using an independent Wi-Fi link. This data link also provided real-time imagery and status information from the SAA system. THE SAA SYSTEM A "threat" aircraft on a collision course will usually appear to be a stationary object in the pilot's visual field [8]. The threat aircraft will occupy a small visual angle until just a short time before the Figure 1. An overview of the systems involved in the SAA flight test and evaluation campaign. SEPTEMBER 2016 IEEE A&E SYSTEMS MAGAZINE 7