Wright Laboratory's Variable-Stability In-Flight Simulator Test Aircraft (VISTA) NF-16D is the newest in-flight simulator in the USAF inventory. A unique research aircraft, it will perform a multitude of missions: to develop and evaluate flight characteristics of new aircraft that have not yet flown, and perform research in the areas of flying qualities, flight control design, pilot-vehicle interface, weapons and avionics integration, and to train new test pilots. The VISTA upgrade will enhance the simulation fidelity and research capabilities by adding a programmable helmet-mounted display (HMD) and head-up display (HUD) in the front cockpit. The programmable HMD consists of a GEC- Marconi Avionics Viper II Helmet-Mounted Optics Module integrated with a modified Helmet Integrated Systems Limited HGU-86/P helmet, the Honeywell Advanced Metal Tolerant tracker, and a GEC-Mounted Tolerant tracker, and a GEC- Marconi Avionics Programmable Display Generator. This system will provide a real-time programmable HUD and monocular stroke capable HMD in the front cockpit. The HMD system is designed for growth to stroke-on-video, binocular capability. This paper examines some of issues associated with current HMD development, and explains the value of rapid prototyping or 'quick-look' flight testing on the VISTA NF-16D. A brief overview of the VISTA NF-16D and the hardware and software modifications made to incorporate the programmable display system is give, as well as a review of several key decisions that were made in the programmable display system implementation. The system's capabilities and what they mean to potential users and designers are presented, particularly for pilot-vehicle interface research.