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 but was instructed to maintain a high speed of 180 knots until reaching 5 nautical miles from the runway threshold. During this phase, the flight crew failed to properly manage the aircraft's descent, causing it to remain significantly above the intended 3-degree glidepath.
In an attempt to correct the descent, the pilot flying engaged an autopilot mode that unintentionally triggered a climb. To rectify this, the pilot disconnected the autopilot and moved the thrust levers to idle. This action transitioned the autothroster into a mode where airspeed was no longer automatically controlled, a change that went unnoticed by the crew. As the aircraft continued its descent, the airspeed dropped rapidly while the descent rate remained far too high for a stabilized approach. Although the crew eventually recognized the low speed and altitude deviations, they did not initiate a go-around until the aircraft was below 100 feet, at which point a go-around was no longer aerodynamically possible.
The aircraft struck a seawall with its main landing gear and aft fuselage, causing the tail to break away from the pressure bulkhead. The wreckage slid along the runway, spun, and impacted the ground. The impact and subsequent fire led to 3 fatalities and numerous injuries, including 40 serious injuries. While 99% of those on board survived, the destruction of the aft galley caused several crew members to be ejected from the plane.
Findings
Investigation into the accident identified several critical contributing factors:
- The flight crew failed to manage the descent properly and did not execute a go-around despite clear indications of an unstabilized approach.
- The unintended deactivation of automatic airspeed control left the crew without proper speed management during the final moments of the approach.
- Inadequate monitoring of airspeed by both the pilot flying and the pilot monitoring due to fatigue, workload, and automation reliance.
- Complexities in the aircraft's autopilot and autothrottle systems that were not sufficiently addressed in pilot training or documentation.
- Lack of effective supervision and nonstandard communication between the crew members during the approach.