After graduating from the B2 school Graf was, at the age of 26, initially thought to be too old for fighter pilot training and was selected for the C school for transport pilots. On 31 May 1939, Graf passed officer-candidate training at Neubiberg. Because the fighter force was in dire need for new officers, Unteroffizier (a rank equivalent to sergeant) Graf was then transferred to 2. Staffel (2nd squadron) of I./Jagdgeschwader 51 (I./JG 51—1st group of the 51st fighter wing) at Bad Aibling . At this time I./JG 51 was equipped with one of the leading fighter aircraft of the time, the Messerschmitt Bf 109E-1. Graf, who had never flown a modern fighter aircraft before, ended his first flight in a Bf 109 with a crash. When I./JG 51 was briefly reequipped with the Czech-built Avia B-534 biplane in July 1939, it gave Graf an opportunity to prove his flying expertise as well as to restore his self-confidence.
