 Although the pace of aeronautical development caused its rapid replacement in frontline service, its useful life was extended into the Second World War with many being converted into target tugs and wireless trainers.In 1933 a Westland Wallace became the first aircraft to fly over Everest, as part of the Houston-Mount Everest Flight Expedition.In 1931, Westland produced the PV-6, a private-venture development of its successful Wapiti.