On June 5438+1October 3 1, 2000, Alaska Airlines Flight 26 1, with the registration number of McDonnell Douglas 83 as, took off from puerto vallarta, Mexico, and finally arrived in Seattle via San Francisco. The plane arrived at San Francisco International Airport at 17: 08+0 1 as scheduled. Passengers on board get off the plane and go through the formalities of entry and departure. 47 of them will continue to fly to Seattle. After the 26 1 flight took off again, everything was normal and the flight was very smooth. 15: 33, the plane is flying at an altitude of 9500 meters and is in a standard autopilot state. The crew received ground instructions to continue cruising at this altitude. 16: 10, the crew suddenly found that the pitching attitude of the aircraft could not be balanced, and the aircraft began to descend and entered a dive. A minute later, at an altitude of 7223 meters, the crew reported that they had regained control of the plane and tried to troubleshoot it. Four minutes later, the crew reported that it was difficult to maintain the altitude, and wondered if the control of the horizontal stabilizer was stuck. They also contacted the company's maintenance personnel in Seattle by radio and asked if the horizontal stabilizer had a switch. The ground technician replied that there was no switch on the tail wing. In view of the fact that the plane has returned to a level flight state, the technicians are optimistic that they will see the crew on the ground. Unfortunately, they will never meet again.