Flight UA948 took off from SFO around 4:40 p.m. local time on July 15. Bound for Heathrow, it was scheduled to cross the Atlantic overnight, but the journey was cut short just past the US–Canada border. Pilots turned the aircraft around and returned to San Francisco after over seven hours in the air.
The Boeing 777-200ER, registered N76021, had already faced delays before departure due to the same technical issue. Whatever fault remained unresolved forced a cautious decision once the aircraft reached cruise.
Tracking data showed a clear arc back toward California, and United informed passengers via its app that safety was the priority. There was no emergency declared, but the flight was ultimately cancelled.
Passengers, many of them connecting through London or on business schedules, were left scrambling. A new departure was scheduled for 1:18 a.m. on July 16, nearly nine hours after the original.
United has not detailed the nature of the fault, and the aircraft remained grounded for inspection.