Hønningstad C5 polar is a Norwegian ambulance and light transport aircraft.
In 1938, aircraft engineers Birger Hønningstad and Viggo Widerøe drew up and submitted the draft of a Norwegian-built ambulance plane, specially adapted to Norwegian conditions. It was to be a single-engine aircraft with 2 pilots and room for 5 passengers or 2 stretchers. The aircraft was designed to use either wheels, skis or floats.
The aircraft was supposed to be ready by the summer of 1940, but war broke out and work on it was brought to a halt. The half finished aircraft was stored in a barn in Bogstad. Work on it was not fully resumed until 1947. The aircraft kept what it had promised and had extremely good flying qualities. Viggo Widerøe proclaimed that it was the best plane he had ever flown. It was in use at several Norwegian airlines from 1948 until 1971, when it crashed in Bodø harbour.