The RB-1's loading ramp, accessed by manually operated clamshell doors, along with the tricycle landing gear, meant cargo could be loaded/unloaded at truck-bed height.

The aircraft could accommodate: The prototype first flew from the Budd Red Lion Factory Airfield in Philadelphia, Pennsylvania on 31 October 1943, piloted by Guy Miller.

[citation needed] At the Budd factory and airfield in Philadelphia, Pennsylvania, there were construction delays due to cost overruns and problems with stainless steel fabrication.

By late 1943, aluminum production had been increased with the construction of new processing facilities, and other more conventional cargo aircraft (such as the Curtiss C-46 Commando and the Douglas C-47 Skytrain) were being produced in large numbers.

On 13 April 1944, during a Naval Air Training Command (NATC) evaluation flight of RB-1 prototype U.S. Navy NX37097 at Patuxent River NAS, Maryland, the aircraft crashed, killing one of the crew.

The new company, founded by members of the AVG Flying Tigers immediately sold four RB-1 aircraft to other buyers, which paid for the entire WAA contract.

[5] The seven remaining National Skyways aircraft were used to transport a variety of cargo, shipping fruit and furniture from its base in Long Beach, California.

The Albuquerque, New Mexico crash was due to a downdraft during a snow storm, 80 miles (130 km) from Albuquerque.[better source needed] Pilot and copilot were killed when they were thrown through the windshield and the aircraft skidded over them; the flight engineer survived.

[citation needed] A single unrestored Budd RB-1, BuNo 39307, is on display at the Pima Air & Space Museum in Tucson, Arizona.