Excerpts from Books and Wikipedia
"British foreign secretary Ernest Bevin insisted that the airlift had to work. And it did. By the end of July, the allies were flying in an average of 2000 tons a day, and by April 1949 that figure had reached 8000 tons, and around 1000 planes using the air corridors at any one time. Stalin decided to cut his losses. The blockade was called off in May 1949. Stalin had instituted the blockade to deter the West from establishing a democratic West Germany. Now in 1949, he had to accept the inauguration of the Federal Republic of Germany, with an outpost in Berlin. The West had not given away to pressure. Nor would they again, for that same year the North Atlantic Treaty Organization was founded." [Furtado: 1001 Days] "While the age of air power enabled the Americans and British to call Stalin’s bluff by flying supplies into Berlin for the next eleven months, until the land access was restored, there had been many who argued for sending a military convoy to force its way to the city. . . . In these circumstances, even isolationist senators could be moved to support proposals for the creation of what was to be the North Atlantic Treaty Organization, with full American membership . . ." [Kennedy: Great Powers, p. 378]