On the morning of 26 May, a Coastal Command PBY Catalina flying boat spotted Bismarck 690 nmi (1,280 km; 790 mi) to the north-west of Brest; she was steaming at a speed that would put her under the protective umbrella of German aircraft and U-boats within 24 hours. The only British forces close enough to slow her down were the aircraft carrier Ark Royal and her escort, the battlecruiser Renown.[52] At approximately 20:30, a flight of fifteen Ark Royal's 820 Naval Air Squadrons Swordfish torpedo bombers launched an attack on Bismarck.