As part of a recent project to research flows in and around a civil cavity configuration ARA developed a Particle Image Velocimetry (PIV) system for it's Transonic Wind Tunnel (TWT). The ARA PIV system is based around the LA Vision PIV system with a custom designed seeding system from ILA (Intelligent Laser Applications). The system is designed to be productive and flexible with translatable laser light sheet positions and the ability to measure in different orientations. Initial tests were performed with a clear working section, these trials proved the seeding quality and capacity as well as confirming the measurement capability. It also had the benefit of confirming the high flow quality of the ARA TWT. The next stage was testing multiple light sheet positions at a range of Mach numbers for the ARA Civil Cavity Research Model. The following image shows a result from two light sheet positions.