 The aircraft were both flown and maintained by members of the Pakistan Air Force, not the U.S. Air Force, a condition mandated by the Pakistanis.The RB-57F prototypes, with the required capability of being a type that PAF airmen could fly, had been purpose-built with the telemetry mission as its goal, and the modification for carrying a two-ton payload in the bomb bay had been made by General Dynamics as part of its development, not by the PAF.From April to October 1965 the two RB-57s each underwent an annual three-month depot maintenance recycle at the General Dynamics plant in Fort Worth required by "Big Safari" rules, which was where "Pee Wee III" No.