What happened
On July 6, 2013, an Asiana Airlines flight arriving from Seoul, Korea, was performing a visual approach to runway 28L at San Francisco International Airport. The aircraft, a Boeing 777-200ER with registration HL7742, was vectored for a straight-in approach. During the descent, the flight crew followed instructions to maintain a speed of 180 knots until reaching 5 nautical miles from the runway. However, the crew failed to properly manage the aircraft's descent, causing the plane to remain significantly above the intended 3-degree glidepath.
In an effort to correct the descent, the pilot flying engaged an autopilot mode that inadvertently caused the aircraft to climb. Upon disconnecting the autopilot, the pilot moved the thrust levers to idle, which transitioned the autothrottle into a mode that no longer controlled airspeed. The crew did not notice this change in automation status. As the aircraft continued its descent, the airspeed dropped rapidly while the descent rate remained excessively high. By the time the aircraft reached 500 feet, the approach was no longer stabilized, yet the crew did not initiate a go-around.
As the aircraft descended below 100 feet, the crew realized the low airspeed and altitude issues, but the aircraft lacked the performance necessary to climb. The aircraft struck a seawall, causing the tail to break off. The wreckage slid along the runway, spun, and impacted the ground. The impact and subsequent fire led to 3 fatalities and 49 serious injuries among the passengers and crew.
Findings
Investigation into the accident identified several contributing factors regarding the crew's management of the flight. The primary cause was the crew's failure to maintain a stabilized approach, specifically regarding airspeed and descent rate monitoring. The crew's inability to monitor airspeed indications was attributed to a combination of automation reliance, fatigue, increased workload, and expectancy bias. Additionally, the failure to use seatbelts by certain passengers contributed to their ejection from the aircraft during the impact sequence.