The June 1934 American Airlines timetable marketed the company's Condor IIs as 'the world's first complete sleeper-planes'. Overnight flights did not catch on and the AT-32D model was made convertible from 12 berths to 15 seats. The DC-3 started as the Douglas Sleeper Transport, though. Photo by: Charles Phelps Cushin

The nose reads 'Condor No 22'. On a flight from Newark to Chicago, the aircraft crashed into Last Chance Hill, near the Mongaup Pond in the Catskill Mountains, on 9 June 1934. The plane was missing for two days. There were no survivors. Photo from: San Diego Air & Space Museum

Carried by the supply ship Jacob Ruppert, this Curtiss Condor was used by Richard Byrd's Second Antarctic Expedition, fitted with floats or skis. The aircraft made it back but only to be scrapped in 1935. Photo from: National Museum of the US Navy

This was the only Curtiss Condor passenger aircraft in Europe. Painted blue with red wings, CH-170 crashed after only three months of service and all twelve people on board were killed. In the United States the Condor was used mainly as a sleeper airliner. Photo by: Walter Mittelholzer / ETH-Bibliothek Zürich