China Southwest Airlines Flight 4509

China Southwest Airlines

Industry	Aviation
Founded	1987
Headquarters	Chengdu , China

China Southwest Airlines Flight 4509 (SZ4509) was a domestic route within China, operating from Chengdu Shuangliu International Airport in Sichuan to Wenzhou Yongqiang Airport in Zhejiang. On February 24, 1999, the Tupolev Tu-154M assigned to this flight crashed during its final approach to Wenzhou Airport, resulting in the loss of all 61 individuals aboard, including passengers and crew.

Aircraft and crew

The aircraft involved was a Tupolev Tu-154M model manufactured in 1990 (serial number 90A-846). It was equipped with three Soloviev D-30 turbofan engines produced by UEC Saturn. Originally registered in the Soviet Union under the test registration CCCP-85846, it was transferred to the Civil Aviation Administration of China (CAAC) in April of that year and re-registered as B-2622.

The cockpit crew included Captain Yao Fuchen (Template:Zh), aged 37; First Officer Xue Mao (Template:Zh), aged 28; Navigator Lan Zhangfeng (Template:Zh), aged 46; and Flight Engineer Guo Shuming (Template:Zh), aged 49. Additionally, seven flight attendants were on duty for this flight.

Accident

On 24 February 1999, as the flight crew readied the airplane for touchdown at Wenzhou Airport, the flaps were deployed at an altitude of approximately 1,000 metres (3,300 ft). Moments later, the aircraft's nose suddenly pitched downward, leading to an in-flight breakup. The wreckage crashed onto elevated terrain and detonated on impact. Eyewitnesses reported observing the plane plummet nose-first from around 700 metres (2,300 ft) before exploding. Tragically, all 61 occupants aboard lost their lives. Additionally, fragments from the crash caused injuries to several individuals on the ground.

Cause

The investigation revealed that improper self-locking locknuts had been fitted within the elevator control mechanism—a fault overlooked by maintenance personnel. During flight, these locknuts loosened and detached, rendering the elevator system unresponsive. This failure resulted in loss of command over the aircraft's pitch axis, ultimately causing the fatal accident.

Aftermath

Alongside the China Northwest Airlines Flight 2303 catastrophe, this incident played a significant role in the decision to retire all Tupolev Tu-154 aircraft from Chinese commercial service by 30 October 2002.

See also

• Alaska Airlines Flight 261
• China Northwest Airlines Flight 2303
• China Southwest Airlines Flight 4146
• Japan Airlines Flight 123
• Emery Worldwide Airlines Flight 17, an accident involving elevator jamming caused by maintenance errors resulting in loss of pitch control.
• Continental Express Flight 2574, a crash triggered by detachment of a deicing boot from an elevator due to inadequate maintenance, leading to catastrophic control loss.