After the single-seat, supersonic F-100 fighter entered service in 1954, it developed a high accident rate, in part due to pilot inexperience with the Super Sabre. In response North American built a two-seat training version -- the F-100F -- to train new Super Sabre pilots. The F-100F retained the basic combat capabilities of the F-100D, including six wing hardpoints to carry external stores, but reduced the number of 20mm cannon from four to two. North American delivered the last of 339 F-100Fs