The U.S. Air Force effort to increase the number of large UAVs in service has stumbled because of problems in obtaining sufficient operators. There has been enormous demand for UAV CAPs (Combat Air Patrols) in combat zones. Four years ago there were a dozen CAPs. Now the air force can send up more than four times as many. The major bottleneck is not UAVs but people trained to operate them. Because of cultural factors unique to the air force, it’s not been possible to recruit, train, and retain enough UAV operators.
Each CAP requires 3-4 Predators or Reapers (one doing the CAP, one or two in transit to the CAP area, and one on the ground undergoing maintenance and repairs). Each UAV has a ground crew to take care of maintenance and repairs, as well as landings and take offs, while a smaller number are back in the United States actually operating the UAVs. To do this round the clock each CAP requires at least three ground
http://www.strategypage.com/htmw/htatrit/articles/20120812.aspx
