This Boeing 747-400 aircraft took off from Detroit International Airport 7 hours ago and was flying at an altitude of 35000 feet over the Bering Strait. Suddenly, the plane made a loud noise, and a warning beep sounded in the cockpit. The plane suddenly made a slope of 35 to 45 degrees. Gett made the right choice in the first place, disengaging from the autopilot, fully holding the steering wheel, stepping on the rudder in the opposite direction with his feet, and striving to control the plane.The first judgment of the flight crew was that the aircraft engine was faulty, but co pilot Fei Gen reported that the aircraft's engine was still working normally, while the fault information on the aircraft showed that the yaw damper was faulty. The flight control page showed that the rudder had turned to the end, deviated 17 degrees, and was fixed there. Captain Getter gave the command, searched for the checklist, flipped through the manual, and attempted to find a solution to the problem. But they soon discovered that there were no descriptions of similar malfunctions in the pilot control manual and aircraft quick inspection checklist. They had never heard of such a malfunction, let alone received training to troubleshoot it, and the plane was almost out of control.At this point, it would take another 5 hours to fly to Narita Airport in Japan. Considering the difficulty of controlling the plane, Gates and Fegan decided to return and fly to the nearest airport - Anchorage Airport in Alaska, USA. The plane happened to fly near the Bering Strait and was unable to contact Anchorage control using regular very high frequency navigation. The crew decided to redirect Northwest Airlines Flight 19 nearby. After receiving an emergency notification from Northwest Airlines Flight 85, Anchorage Control directed the aircraft to turn right and fly towards Anchorage.In the cockpit, the crew is working hard to control the aircraft. They contacted the headquarters of Northwest Airlines in Min