A United Airlines flight from Los Angeles to Shanghai had to turn back after the pilot realised he had forgotten his passport. Flight UA198, a Boeing 787-9 with 257 passengers, took off at 2 pm for a 13-hour journey. But two hours into the flight, it made a U-turn over the Pacific Ocean and landed in San Francisco just before 5 pm. Advertisment The incident happened on Saturday, (Mar 22), causing a long delay for passengers, as reported by The Independent. Also Read | 'Nazis got better treatment than Venezuelans' under Alien Enemies Act by Trump administration, says US court The airline apologises and provides compensation AdvertismentUnited Airlines apologised for the inconvenience, offering a $15 meal voucher and instructions for compensation. In a statement, the airline said: ""On Saturday, United flight 198 from Los Angeles to Shanghai landed at San Francisco International Airport as the pilot did not have their passport abroad. We arranged for a crew to take our customers to their destination that evening."" Also Read | 'Most fragile snowflake in history': Trump's Colorado portrait to be taken down after US president throws a fit Passengers express frustration Advertisment Many passengers were upset and shared their frustration online. One traveller posted on Reddit, “What would happen though if the plane landed? Surely they would only find out once the plane had landed and the pilot was in the airport? There must be a way to authenticate a pilot other than passports like a backup on some type of system?” Also Read | 'Most fragile snowflake in history': Trump's Colorado portrait to be taken down after US president throws a fit Delayed arrival in Shanghai A replacement flight finally took off from San Francisco at 9 pm, landing in Shanghai early Sunday morning. While passengers reached their destination, many were left frustrated by the unexpected delay. (With inputs from agencies)