The Curtiss-Wright C-46 made its first flight on March 26th 1940. Pan Am didi not ordered wery often second hand airliners in those year but didi so with the Commando. They bought them from the army after the secon world war. Pan Am used them in the Latin American Service and sold them back to the army by 1953. They did a good job but the DC-3 where better for passenger use und so Pan Am serverd them only 5 years. Another case why they sold them might be that Douglas introduced the DC-6 in 1952 and the DC-4 had already done a good job from the mid '40.