The original calculations for the flight were that in early summer, including twilight, 20 hours of daylight were available for the flight. By averaging 160 miles an hour, the distance of 2,670 miles from New York to San Francisco could be covered in 16 hours 40 minutes. Mitchell had struck a deal with Curtiss Aircraft to purchase 25 new PW-8 fighters, patterned after the R-6 Racer, if Curtiss would help modify one of the prototypes for use in the project. The D-12 engine on the PW-8 produced 435 horsepower and Mitchell's intended modifications were to enable it to make the flight at full throttle power setting. If the armament and unnecessary equipment were also removed from the XPW-8, additional fuel capacity could be installed to extend its range, and larger oil tanks for engine cooling. The flight plan calculated four stops of 30 minutes each for refueling. McCook Field; Saint Joseph, Missouri; Cheyenne, Wyoming; and remote Salduro Siding, Utah, were selected as refueling points, following a recently established mail route.
Lt. Maughan was chosen to make the flight because he was an experienced test pilot and a combat veteran accustomed to dealing with in-flight emergencies, and because he had already established speed records in 1922 and 1923.
The second attempt to set the record was made on July 19. After a 5:08 a.m. takeoff, Lt. Maughan completed the 570-mile first leg to McCook Field at 8:35 a.m, taking off again at 8:53 a.m. After reaching Saint Joseph, where he spent 39 minutes on the ground, Lt. Maughan experienced severe nausea from oil fumes on the next leg. He reached Cheyenne, however, where a broken oil line was found and soldered together. Approximately 90 minutes after leaving Cheyenne the oil line ruptured again and the nausea forced him to land at the air mail field at Rock Springs, Wyoming.
The first two attempts had indicated that maximum performance was stressing the engine of the PW-8, necessitating that additional time be factored into the flight plan. With available daylight already reduced by a half hour by the date of the second attempt, no further tries were made in 1923.
Lt. Maughan took off from Mitchel Field at 3:58 a.m. Eastern Standard Time, June 23, 1924. He flew through intermittent rain and fog but still averaged 135 mph and reached McCook Field at Dayton at 8:10 a.m. EST. Although mechanics serviced the plane around in twenty minutes, one of the field's mechanics over-torqued the filler cap, securing it to the fuel intake housing and broke off the valve. The housing had to be removed, soldered, and replaced, costing an hour's delay.
Lt. Maughan encountered thunderstorms between Dayton and St. Joseph, but reached Saint Joseph without incident. The grass field there was soft from heavy rain, limiting the takeoff weight of his plane. Unable to take on a full load of fuel, Lt. Maughan flew to North Platte, Nebraska, where he completely filled the fuel tank, but which caused a further 20-minute delay.
The detour to North Platte also resulted in Lt. Maughan encountering a strong headwind, slowing his average groundspeed. He landed at the air mail field at Salduro Siding, a railroad stop adjacent to the Bonneville Salt Flats, at almost 6:30 p.m. local time and calculated that reaching San Francisco by dusk was still possible.
The last leg of the flight, over Nevada and the Sierra Nevada Mountains, was characterized by cloud strata, making navigation difficult in low light conditions. Lt. Maughan, from Logan, Utah, was familiar with the terrain however and recognized sufficient landmarks to approach San Francisco Bay from the north. He used a revolving light on Alcatraz Island to guide him to Crissy Field, the military airfield at the Presidio of San Francisco, where he landed in front of an estimated 50,000 spectators at 9:46 p.m. Pacific Standard Time, reportedly a minute before dusk.
Maughan's total flight time was 20 hours and 48 minutes. In addition to the publicity value of being the first transcontinental crossing within the hours of daylight, the flight established new records for time, distance, and average speed (128.37 mph) in transcontinental flights.