In April 1928 Maddux started passenger service from Los Angeles to San Francisco, California, with scheduled stops in Fresno and Oakland and, by reservation, in Visalia and Bakersfield.

On August 26, 1929 a Maddux Tri-motor, along with other aircraft, escorted the famous LZ 127 Graf Zeppelin airship to Mines Field (now part of Los Angeles International Airport) where it stopped during its around the world flight.

These included Will Rogers, who rode on the inaugural flight, and Hollywood actors Arthur Edmund Carewe and Dolores del Río.

On April 21, 1929 a Maddux Air Lines Ford 5-AT-B Tri-motor was involved in a midair collision with a single-engine U.S. Army Boeing PW-9D pursuit biplane near San Diego.

The army pilot, Lieutenant Howard W. Keefer, tried to bail out of the wreckage, but his parachute got entangled, and both aircraft crashed near the Lexington Park subdivision of eastern San Diego on the side of a canyon.

Flying from the races at Agua Caliente Racetrack, near Tijuana, Mexico to Los Angeles, the plane encountered rain, low clouds, fog, and possibly engine problems.

Charles Lindbergh, as chairman of TAT-Maddux's technical committee, was involved in the investigation and made an aerial inspection of the crash site after the disaster.