The Horseshoe Route was a flying boat route between Sydney, Australia, and Durban, South Africa, via Singapore and Cairo during World War II. Mail could then be sent by sea between South Africa and Britain. Using Short Empire C Class S23 and S33 flying boats, British Overseas Airways Corporation (BOAC) operated the section between Durban and Sydney while Qantas Empire Airways operated the section between Singapore and Sydney. In October 1941, Qantas took over the Karachi - Singapore section as BOAC were short of pilots. The Horseshoe run was a ninteeth century Australasian shipping route.