The great expansion of the Coast Guard incident to anti-smuggling activities during the Prohibition years brought about a major expansion in radio communication capabilities. Prior to that time cutters were equipped with Navy type radio equipment and used Navy frequencies for handling ship-shore traffic. The need developed for a vast and far reaching radio communication service that could be provided by other sources. In addition to traffic generated by the increased number of cutters there was a tremendous amount of traffic to and from the large number of patrol boats. There was also, for the first time, the requirement for aircraft radio communication. Coast Guard aircraft of this period were allocated International Wireless Telegraphy call signs as a means of identification. To take care of this traffic, a shore radio station was established at Rockaway, New York. This station proved highly successful and as a result additional units were established at Nahant, Massachusetts; New London, Connecticut; Cape May, New Jersey; Cape Henry, Virginia; Fernandina, Florida; Fort Lauderdale, Florida; Mobile, Alabama; San Francisco, California; San Pedro, California; Port Angeles, Washington; and Anacortes, Washington.
While performing law enforcement duties the Coast Guard was simultaneously engaged in search and rescue operations. The radio communications network was of tremendous value in identifying, locating, and directing aid to those in peril on the sea. Beginning in 1929, initial steps were taken to establish a radio communication network for aircraft. Inaugurated along the Atlantic Seaboard, the aim was to keep track of all aircraft using the coastal routes. Aircraft departure and arrival times were given and by means of check times provided when abeam a designated station; aircraft on long distance flights were afforded continual radio observation and contact. With no additional cost to the Government, adequate monitoring of airborne traffic was provided. There was a chain of lifeboat stations along the coast with land line connections. These were depicted on the air-navigation charts. When an accident did occur or help was needed, the nearest Coast Guard station was ready with immediate assistance.
During the first two months of operations, 329 aircraft availed themselves to this service. In 1932 statistics showed that over 1,400 reports by transit aircraft were made up and down the Atlantic Seaboard. As more air stations were established the system was extended to the Gulf and Pacific Coasts. In 1936 the Bureau of Air Commerce began to development a nation-wide air traffic control system. The Civil Aeronautics Authority came into being in 1938 and began air traffic control operations negating the need for Coast Guard flight following. The Coast Guard radio network, however, continued to expand. Besides broadcast messages the network handled direct traffic between Coast Guard aircraft, cutters, boats, and shore stations.
