Revenue service
Revenue service began on the New York City Subway on May 17, 1974; the SOAC ran on the A, D, E, and N services until July 19. It was then operated in revenue service on the MBTA Red Line in Boston for a month beginning on August 19, 1974. The SOAC demonstrator was then tested on the CTS Airport Line later in 1974, with fifteen days of revenue service.