Figure 3

This figure represents how the spiral development process starts with new system objectives, alternatives, and constraints being identified. It is followed in a circular pattern with evaluating alternatives and identifying and resolving risks. Next, a product prototype is developed. Then, in a continuing spiral configuration, the product is further refined by repeating the same procedures until the product is finalized. The final system is thoroughly evaluated and tested. Routine maintenance is carried out on a continuing basis to prevent large-scale failures and to minimize downtime.

At the customer's option, the entire project can be aborted at any time if the risk is deemed too great. Risk factors might involve development cost overruns, operating-cost miscalculation, or any other factor that could, in the customer's judgment, result in a less-than-satisfactory final product.