Nah, Boeing, Lockheed, and Douglas never preceded from a scale model due to the US putting rules and regulations on supersonic flights back in the 50's or early 60's. Meaning that they could only fly at or past Mach when over water. When flying over land they would have to fly at cruise speed. Pan Am, Delta, North West, many others looked at obtaining a fleet. But, the rules and regulations and the Nixon administration cut the government funding for research and development completely.
Some of these fights could be ferry flights to drop off the aircraft at a maintenance facility for an A, B, C, or a D check. Southwest flies to the airport that I work at just to bring the aircraft for maintenance. And I work at MIA airport where Southwest doesn't have scheduled flights to.
This is the second design problems with the 737's. The first was the Rudder Power Control Actuators that had the valves that got of alignment and reversed the flow of the actuators. Left rudder pedal movement gave you a right rudder. Right pedal movement gave you a left rudder. As for the DC-10's it was the Aft Cargo Doors that depressurized the aircraft. Like the De Havilland Dash-8's or Bombardier Q400's are doing now. The second problem for the DC-!0's was American doing engine changes with the pylons and a forklift. Less wiring and hose connections.
