controller tasks will eliminate the need to infer task load to derive estimates of PTT. Using a single model for estimating task load rather than separate ones for each controller is the preferred approach, since it will facilitate both PTT conversion and model validation.
Task performance data should be used also to assess the validity and impact of all key modeling processes, relationships, and assumptions. Because it is not possible to validate PTT estimates against actual staffing levels, ensuring that the model elements are well justified and viewed as credible is vitally important. Examples of modeling assumptions that would seem to warrant early attention are those that concern task performance by the controllers when working alone and in teams, whether tasks are performed sequentially or concurrently, and how total task load affects the pace of task performance.