In the past, and to a large extent even today, the emphasis in system design has been on defining hardware requirements. In many cases, advances in hardware technology, and not the ability to meet mission requirements, were the driving factor that determined the need for upgrades to or replacement of a weapon system. Even though software has increased in importance and percentage of cost in system development, it is still philosophically considered as a means to facilitate hardware performance. This thinking has had an adverse effect on system performance by relegating decision requirements, which can be derived directly from mission requirements, to a minor or nonexistent role in the system design process. It is the premise of this paper that system design should be dictated by decision requirements since decisions humans make determine how well and to what degree a weapon system's inherent capabilities will be utilized. A system design approach based on an emphasis of the human in his role as a decision-maker is presented. NATO Furnished. (rh), This article is from 'The Design, Development and Testing of Complex Avionics Systems: Conference Proceedings Held at the Avionics Panel Symposium in Las Vegas, Nevada on 27 April-1 May 1987', AD-A198 666, p16-1 thru 16-9.