Unlike the Hampden and Wellington, which had met Specification B.9/32 for a day bomber, the Whitley was always intended for night operations alone and thus escaped the early heavy losses received during daylight raids carried out upon German shipping. As the oldest of the three bombers, the Whitley was effectively obsolete by the start of the war, yet over 1,000 more aircraft were produced before a suitable replacement was found. A particular problem with the radar-equipped Mk VII, with the addition of the drag-producing aerials, was that it could not maintain altitude on one engine. Whitleys flew a total of 8,996 operations with Bomber Command, dropped 9,845 tons (8,931 tonnes) of bombs, and 269 aircraft were lost in action.