DHC-6 Twin Otter / Wien AirDHC 6 Twin Otter Wien Air airplane model. The first flight of the DHC 6 Twin Otter was on May 20, 1965. Over 900 of the aircraft have been built so far, and it is currently still in production. The DHC 6 Twin Otter is a Canadian 19 passenger STOL (Short Takeoff and Landing) utility aircraft developed by de Havilland Canada and currently produced by Viking Air. The aircraft's fixed tricycle undercarriage, STOL abilities and high rate of climb have made