Investigation Summary
The accident sequence began during the flight's second approach to Runway 22 in heavy rain and turbulence. During this attempt, the aircraft experienced a severe vertical oscillation (pilot-induced) and a sudden downdraft, causing the nose gear to strike the runway surface with significant force before the crew initiated a go-around. This impact was severe enough to cause structural damage in the nose gear bay, specifically rupturing hydraulic lines. As the crew prepared for a third landing attempt, they were unaware that the hydraulic fluid for the braking system had leaked out. Upon the final touchdown, the Autobrake and manual braking systems failed to engage. The aircraft continued down the entire length of the runway, overrunning the end before coming to rest near the airport boundary.
Final Conclusions
The investigation concluded that the primary cause was a loss of hydraulic pressure in the systems responsible for braking and nose-wheel steering, resulting from a hard impact during a previous missed approach. Contributing factors included severe weather conditions (thunderstorms and wind shear), pilot-induced oscillations during the second approach, and the crew's failure to recognize the extent of the mechanical damage before the final landing attempt.
Photographic Evidence (1)
Video Analysis
The Runaway Plane | Korean Air 631 — An analysis of the Korean Air 631 runway overrun in Cebu, detailing the hydraulic failure and the challenging weather conditions that led to the hull loss.
If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Hydraulic System
The impact during the second approach ruptured lines in the nose gear bay, leading to a total loss of fluid in the hydraulic system.
Braking System
The loss of hydraulic pressure rendered both the normal and alternate braking systems, including the anti-skid, inoperative.
Nose Wheel Steering
The hydraulic failure also disabled the steering mechanism, leaving the pilots unable to steer the aircraft on the ground.
Interesting Facts
- 01The aircraft was 24 years old at the time of the accident and was written off as a total hull loss.
- 02Despite the severe damage to the cockpit and forward fuselage, all 173 occupants survived.
- 03The nose gear impact during the second attempt was so severe it triggered a 'Brakes No Anti-Skid' warning on the ECAM.
- 04The aircraft came to a stop approximately 300 meters past the runway end.
- 05This was the first hull loss for Korean Air since the crash of Flight 8509 in 1999.
Safety Actions & Advisories
Korean Air Safety Audit
Following the accident, Korean Air underwent a comprehensive safety audit and retired its remaining older Airbus A330-300 aircraft earlier than planned.
Operational Procedures Update
The airline revised its flight crew training to emphasize decision-making during multiple missed approaches and technical malfunctions in adverse weather.