force of 12 He 111 torpedo-bombers attacked in small groups, but almost half were shot down by the anti-aircraft barrage and the Sea Hurricanes, which were in position to intercept them this time. At 03:30 on 14 September, a U-boat torpedoed and sank a tanker at the rear of the convoy. A patrolling Swordfish attacked at 04:00 and forced a surfaced U-boat to dive, although the submarine did not appear to be damaged. Another Swordfish sighted at 09:40; this submarine also dived, but was located and sunk by . Avengers captain now had to change tactics to work around a limitation of the Sea Hurricanes and Fairey Swordfish: They were not able to use the USN designed catapult which required a tail down take off, rather than the tail up method used by the Royal Navy's catapults, and so needed the full deck length to take off. He endeavoured to keep a section of fighter aircraft in the air during daylight hours and another ready to launch, so they could break up large German aircraft formations. This entailed a continuous cycle of take offs and landings to re-fuel and re-arm. At 12:30 a group of 22 Ju 88s and He 111s with an escort of Messerschmitt Bf 110s approached the convoy from dead ahead. Aboard Avenger, nine Sea Hurricanes took off. Their presence forced some of the German planes to drop their torpedoes early and turn away, while others were shot down by the anti-aircraft barrage. A simultaneous attack by a force of 14 Ju 88s at the rear of the convoy divided the Sea Hurricane squadrons, which shot down one of the Ju 88s. The carrier and escorts were targeted by the German aircraft, and about 20 aircraft succeeded in making a bombing run. One aircraft was shot down by the barrage, the eleventh of the day. Immediately following, at 15:30, 25 He 111 torpedo bombers appeared in front of the convoy. Of these, 17 targeted Avenger, which managed to evade all the torpedoes. However, three of her Sea Hurricanes, which had closed on the He 111s, were shot down by the escorts' barrage. The pilots were all rescued. Another force of Ju 88s appeared and targeted Avenger and Scylla. Neither ship was hit, but a number of near misses were recorded. One near miss started a small fire in Avengers catapult room, which was quickly dealt with. That