06/30/2008. Remarks by Johan Visschedijk: "Boeing started the design of the all-metal single-seat mail/cargo transport Model 200 Monomail in 1929. Powered by a 575 hp Pratt & Whitney Hornet B nine-cylinder, single row, air cooled radial engine, and registered NX725W, the prototype was first flown on May 6, 1930. It was tested for some time and then converted to the eight passenger configuration Model 221A, by lengthening the fuselage by 2 ft 3 in (0.69 m) to 43 ft 5 in (13.23 m) and adding four cabin windows on each side.

Reregistered NC725W the aircraft served with Boeing Air Transport and United Air Lines, before it was acquired by Wyoming Air Service. On May 27, 1935, piloted by Alva Lucas through very bad weather with low visibility, the aircraft impacted high terrain near Glendo, Wyoming, while en route from Billings, Montana to Cheyenne, Wyoming. The pilot was killed instantly and the aircraft destroyed."