Australia, Britain, Canada, Finland, and the United States used the UC-61.
Start of World War II
With the start of World War II many of the civilian Fairchilds were pressed into military service in Australia, Canada, and Finland.
Britain received 831 UC-61s via Lend Lease which was a majority of the UC-61s produced.
Many Flights and Communications Units received the Argus. The No 173 in Heliopolis in Egypt was the only regular Royal Air Force squadron to be equipped with them.