International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Over the last 3 years the Naval Air Warfare Center Aircraft Division (NAWCAD), Patuxent River, MD, has been in the process of developing a link between its secure Manned Flight Simulator (MFS) and Real Time Processing System (RTPS) facilities. The MFS hosts a wide variety of high fidelity fixed and rotary wing aircraft simulation models. The RTPS is used as a telemetry ground station for conduct of Navy flight testing at Patuxent River MD. The ability to integrate simulation with flight testing in a real time environment provides new potential for increased flight safety, enhanced engineering training, optimized flight test planning, real time simulation fidelity assessments, improved engineering analysis and other applications for enhanced flight testing, data analysis and data processing. A prototype system has been successfully designed and operated at NAWCAD in support of an F/A-18C flight test project which required simultaneous merging and display of real time and simulation data to reduce the risk of departure from controlled flight. As currently designed the link (encryption and decryption gear in the loop) can be operated in three modes: (1) Simulation sending data to RTPS (e.g. pilot-engineer pre-first flight preparation/training scenario, (2) simulation is driven by real aircraft control surface inputs and response is compared with that of the real aircraft for simulation fidelity assessments and (3) simulation "rides along" with the real aircraft and data are extracted from the simulation which are otherwise unavailable from the aircraft (e.g. flight control law interconnect signals, control law feedback signals, aerodynamic data, propulsion model data, avionics model data, other model data etc.). This paper discusses, design and implementation aspects of the RTPS-Simulator link, and includes a description of how the link was used to support a real time flight test program by providing critical safety of flight data. Other potential uses for the link will also be highlighted.