Aviation fuel
After five years of war and heavy attrition many of the "Luftwaffe's" pilots were inexperienced and poorly trained, deficient in marksmanship and flight skills. There was a shortage of experienced instructors, and many of the training units were forced to fly front-line operations in order to bolster the front-line "Jagdgeschwader". Aviation fuel supplies were also at a premium, limiting the duration of training. Long-range Allied fighters exacerbated this situation by shooting down many training aircraft. By late 1944 there were no safe areas in which pilots could be trained without the possibility of air attack. The result was a "vicious circle": poorly trained pilots were quickly lost in combat or accidents, and the need to replace them put more pressure on the training system. Allied personnel who witnessed the attacks remarked on the poor aim of the strafing aircraft, and many of the "Luftwaffe" aircraft shot down by Allied anti-aircraft fire were caught because they were flying too slowly and too high.