In 1948 the Coast Guard was called upon to provide aviation support for agents of the Treasury’s Alcohol Tax Unit. In order to avoid detection, the manufacture of illicit whiskey, commonly referred to as ‘Moonshine,” typically took place in hard to reach remote areas. Most common locations were the deep woods or a swamp. One method used by law enforcement to address this was aerial surveillance. From the air, the difference between growing bushes and those cut and put over a still could be seen. The still, whether in the deep woods or a swamp, had to be reached and if specific routes to a still were used these quite often could be detected from the air.
The type of aircraft needed for this function was small, lightweight, slow-flying, and capable of making tight turns. One of the many World War II light aircraft meeting these requirements was the US Marine Corps OY-1 Sentinel. The Coast Guard obtained seven OY-1 aircraft in 1948. Four were operational and three were used as spares. The aircraft were based out of the Coast Guard Air Station Elizabeth City and deployed to targeted areas for specific missions. The aircraft were flown by Coast Guard aviators and carried an ATU agent. During May 1949 all but one of the OY-1s were retired and in 1952 an OY-2 was added to the inventory.
In 1958 the last OY was surveyed. All future support efforts for the ATU/ATF were performed by helicopter.