Mosaic ATM conducts rapid prototyping of complex decision support tool algorithms as a fundamental component of spiral development. Because decision support tools provide critical information to human operators, it can be difficult to determine functional and performance requirements. System acceptance is of paramount importance and consideration in requirements formulation. However, the subjective nature of system acceptance by a human user must be converted into objective requirements for full-scale system development and deployment. By using rapid prototyping and demonstration of decision support tools, functional and performance requirements can be determined and validated.