A Tokyo-bound flight made a U-turn while flying over the Pacific Ocean and returned to Los Angeles because one passenger, for reasons still unclear, had boarded the wrong flight. All Nippon Airways Flight 175 left the Los Angeles International Airport at about 11:30 a.m. Tuesday Pacific Standard Time, spent about eight hours in the air and landed back in California just after 7:30 p.m., majorly inconveniencing its passengers, including model Chrissy Teigen, who live-tweeted the "flight to nowhere" to her 9.2 million followers. Teigen, who was traveling with her husband John Legend, wrote on Twitter that the plane was turned around about four hours into the flight. The Twitter world watched in amusement as Teigen kept her followers updated on the ordeal, which apparently involved an hours-long wait at the airport, unanswered questions, some police presence and a microwaveable Ramen meal. The incident involved two brothers, one of whom was an authorized All Nippon Airways, or ANA, passenger while the other had a United Airlines ticket, Transportation Security Administration spokesman Mike England said. The brothers, who were not identified, went through security screening without incident and had valid passports and boarding passes. Both were headed to Tokyo and were scheduled to leave around the same time. Both ended up on the ANA flight even though only one of them was an authorized passenger. It remains unclear how that happened. The airline said the decision to turn around was part of a security procedure. Weather concerns, mechanical problems, medical issues and terrorist threats are among the common reasons for diverting a plane. Others are unusual, but not unheard of. In 2015, for example, a British Airways flight flew back to Heathrow Airport just 30 minutes into the seven-hour flight to Dubai because of an overwhelming odor coming from the lavatory. A similar incident happened earlier this year, when a SpiceJet flight headed to New Delhi was diverted because of a "very foul smell" coming from the lavatory.