China Southwest Airlines Flight 4509 (SZ4509) was a flight from Chengdu Shuangliu International Airport, Sichuan to Wenzhou Yongqiang Airport, Zhejiang. On February 24, 1999 it crashed into a field while on approach to Wenzhou Airport, killing all 61 passengers and crew members on board. Witnesses saw the plane nose dive into the ground from an altitude of 2,300 feet and explode.

Following the incident all Tupolev Tu-154 aircraft in China were taken out of service.

Aircraft

• Model: Tupolev Tu-154M
• Registration: B-2622
• Serial Number: 90A-846
• Engine: Soloviev D-30
• Year of Delivery: 1990

Crew members

• Captain: Yao Fuchen (姚福臣);
• First Officer: Xue Mao (薛冒);
• Flight Engineer: Guo Shuming (郭树铭);
• Flight Navigator: Lang Zhanfeng (郎占锋).

Cause

Incorrect locknuts had been installed in the elevator operating system. These spun off during the flight, leaving the elevator uncontrollable.

Flight Number

In 2002, China Southwest merged with Air China. Air China did not retire the flight number, but its destination airport was changed from Wenzhou Yongqiang Airport to Shanghai Pudong International Airport. As of February 25, 2014, the route is flown using an Airbus A320.