The Beaver was designed for flight in rugged and remote areas of the world. Its STOL capability made it ideal for areas normally only accessible by canoe or foot. Because the aircraft often flies to remote locations and in cold climates, its oil reservoir filler is located in the cockpit and oil can be filled in flight. A series of upgrades to the basic design were incorporated. One major customer introduced the use of flat steps replacing the earlier tubes, a feature now almost universal. In 1987, the Canadian "Engineering Centennial Board" named the DHC-2 as one of the top ten Canadian engineering achievements of the 20th century.