Martin 404 / PiedmontMartin 404 Piedmont Airlines airplane model. Attempting to gain a share of the post World War II demand for civil airliners, the Glenn L. Martin Company flew the prototype of a twin engine 36 40 seat transport airplane designated Martin 2 0 2 on November 22, 1946, entering service in 1947. Also in 1947, Martin had flown another prototype airplane called the 3 0 3, but as a result of the loss of a 2 0 2 in 1948 due to wing structural failure, it was