DARPA's Persistent Close Air Support (PCAS) program envisions more precise, prompt, and easy air-ground coordination for close air support - delivery of airborne munitions to support ground forces - and other missions under stressful operational conditions and in complex environments. It aims to do so through the development of a system that enables the sharing of real-time situational awareness and weapons-systems data, using technologies compatible with almost any aircraft. Among the system’s envisioned benefits is a capacity to use smaller munitions to hit smaller, multiple, or moving targets while minimizing the incidence of friendly fire and collateral damage. PCAS includes two main components, PCAS-Ground and PCAS-Air. PCAS-Ground is specialized situational awareness and mapping software on commercial Android tablet computers. PCAS-Ground communications with aircraft pilots through PCAS-Air: a modular plug-and-play system designed to adapt to nearly any aircraft.