Phoenix use a formal structured design and development process.  The process comprises several key steps.  Progress thorugh the process is generally linear but most stages overlap the adjacent ones to some degree.  Issues found at any stage are rectified by going back to the appropriate stage in the process for the particular issue. The process features formal feedback loops to ensure that issues are captured and tracked to completion.

A key feature of the process  is that it allows for easy design change at the front end of the process but gradually introduces more controls as the design nears maturity until it reaches full engineering change control by the time the product reaches production.

Phoenix Engineering Development Process