Impact of maintenance staffing on availability of the US air traffic control system

This paper describes a model for assessing the impact of staffing on outage times and availability in the US national network of air traffic control equipment using a finite queuing model. Because of the wide geographic distribution of FAA facilities and equipment, maintenance is provided out of a national network of cost centers. Each such center has a limited number of technicians ("servers") who are responsible for providing scheduled maintenance and repair for the equipment assigned to that center. When an equipment requires service and a qualified technician is available, then the outage time is simply the repair time. However, if there are equipment failures when technicians are busy making other repairs, then there is an additional waiting time until a qualified technician is free. The model determines average outage times as a function of the number of technicians assigned to a cost center, equipment failure rates and the number of equipment which technicians must support.