|One of Western Air Express' Douglas M-2 mailplanes during a maintenance runup.|
WAE was formed in order to bid on the newly-offered Contract Air Mail (CAM) route #4. When WAE was first incorporated on July 13, 1925 by the owner of the Los Angeles Times, Harry Chandler, they bought a large tract of former cattle ranch land (a different source calls it a wheat field) along with an empty movie studio sound stage (which was converted into a hangar) from the Vail brothers and five Douglas M-2 mail planes.
Douglas had originally designed their M-1 as an effort to capture business from the Postal Service, who for years had been carrying mail in old DH-4s. The M-1, while promising, didn't make it into production before the airmail service transitioned to private contractors. However, WAE signed up for the improved M-2 model, which included a more efficient flat frontal radiator. After receiving their initial five, they bought a sixth M-2, two M-4s and the only M-4A (an M-4 with a 425hp Liberty instead of the standard 400hp).
In 1930, WAE moved their headquarters to nearby Alhambra airport, where they spent a million dollars on a new hexagonal hangar and shop facility (they didn't stay there long, soon moving to Grand Central Air Terminal at Glendale in 1932), so it seems that our two photos would have been taken near the very end of WAE's time at Vail.