What is the setting of Fate is the Hunter by Ernest K. Gann?

Gann attended flight school and was trained as one of the first commercial pilots in the United States of America. He flew commercial routes in New England for a few years prior to World War II. Then, throughout the war, he flew as a civilian pilot for the Air Transport Command. After the war, he found the return to short flights in New England somewhat boring and joined a startup company flying between California and Honolulu.