 Nonscheduled air service, which then referred to light aircraft individually chartered to transport cargo, was exempt.Snapping up $25,000 Douglas DC-3s, the legendary utility plane which operated in numbers exceeding 10,000 during the war, enterprising pilots established their own freight carriers with ease under the 1938 exemption.A glut of such companies appeared—2,730 in 1946 alone according to the Civil Aeronautics Board (CAB), which replaced the CAA in 1940.