the long-ranged P-51s as the spring of 1944 wore on, American fighter pilots on bomber defense missions would primarily be flying far ahead of the bombers' combat box formations in air supremacy mode, literally "clearing the skies" of any Luftwaffe fighter opposition heading towards the target. This strategy fatally disabled the twin-engined Zerstörergeschwader heavy fighter wings and their replacement, single-engined Sturmgruppen of heavily armed Fw 190As, clearing each force of bomber destroyers in their turn from Germany's skies throughout most of 1944. As part of this game-changing strategy, especially after the bombers had hit their targets, the USAAF's fighters were then free to strafe German airfields and transport while returning to base, contributing significantly to the achievement of air superiority by Allied air forces over Europe. During the Big Week bomber campaign of late February 1944 which started to introduce the new fighter tactics, American medium and heavy bombers together dropped roughly 10,000 tons of bombs and seriously disrupted German fighter production. During Big Week, the Eighth Air Force lost 97 B-17s. Coupled with B-24 losses the figure totaled 137 initially and 20 more scrapped due to damage. The Fifteenth Air Force lost 90 aircraft and American fighter losses stood at 28. The Luftwaffe losses were high amongst their twin-engined Zerstörer units which suffered heavy losses and decimated the Bf 110 and Me 410 Gruppen. More worrying for the Jagdwaffe was the loss of 17 per-cent of its pilots; nearly 100 were killed. The tide had turned, and air superiority had passed to the Western Allies. When long-range fighter support became widely available by May 1944, the Luftwaffes defensive effort was severely damaged. The P-51D Mustangs and P-47 Thunderbolts with extended range were now able to escort the bombers to and from the target. The Luftwaffe now did not have opportunity to attack the unprotected fleets. The resulting air battles diminished the strength of the Jagdwaffe. U.S. and RAF fighters undertook many fighter sweeps, and the boundaries of the front line steadily moved eastward. They engaged many Luftwaffe training aircraft, and the helpless Jagdflieger of tomorrow were shot down in droves. Pilot training had become shorter in order to fill the front line Gruppen, which often had more aircraft than pilots. German aircraft production reached its peak in August 1944, finally equaling the Soviet and American output, but the production came too late to alter the outcome of the air