The history of Scandinavian Airlines System (SAS) from 1933 to 1951 covers the first attempts at transatlantic travel, the establishment of a consortium and finally the establishment of the consolidated SAS. Aerotransport, the national airline of Sweden, and Det Norske Luftfartselskap (DNL), the national airline of Norway, both started planning transatlantic routes in the mid-1930s. By 1939, negotiations were started with Det Danske Luftfartselskab (DDL) of Denmark, and by 1940 services were to begin. Because of the German occupation of Denmark and Norway, the plans collapsed. In Sweden, Svensk Interkontinental Lufttrafik (SILA) was founded to start private transatlantic flights, which commenced in 1945. Negotiations were started again, and in 1946 the consortium Overseas Scandinavian Airlines System (OSAS) was established to start routes to New York and South America.