Historically, aircrew training devices were developed after the aircraft were well into production and after the requirements for the training devices were well established. These requirements often reflected aircraft capabilities and failed to take training considerations into account. Currently, aircrew training systems demand the design and manufacture of training devices while the aircraft they replicate are still in development. As a result, training requirements that drive the development of aircrew training devices as well as contribute to aircraft and training systems designs must be determined before the first production aircraft becomes operational. The traditional Instructional Systems Development (ISD) approach, which assigns training objectives to existing training media or to the capabilities of existing training devices, does not readily apply to the concurrent development of training devices with aircraft systems. This paper describes an approach used for the development of aircrew training devices concurrently with the development of an aircraft system. This forward-looking approach defines training requirements, which in turn drive the design of the aircrew training devices. These training requirements establish the training capabilities of the devices as well as the operational threat environments those devices fly into. Included are the process for the integration of training requirements into engineering design specifications, the resolution of technical and cost factors, the established interfaces between the training analysts, engineers and the users, and the traceability and currency of the training device.