PT-19 CornellFairchild PT 19 Cornell airplane model. Built to meet a 1939 Air Corps request for a new primary trainer, nearly 7,800 PT 19 derivatives were produced between 1940 and 1944. Pilot instructors before World War II had voiced the need for a more challenging trainer, to ease student transitions from primary to advanced flight instruction. It was felt that this approach would better prepare students to fly the high performance fighters then in development,