Korean Air Flight 631

Korean Air
Industry	Airline
Founded	March 1, 1969; 57 years ago
Headquarters	Seoul, South Korea
Area served	International
Products	Passenger and cargo air transport services
Website	www.koreanair.com

Korean Air Flight 631 was an international passenger service operating from Incheon International Airport near Seoul, South Korea, bound for Mactan–Cebu International Airport in Metro Cebu, Philippines. On 23 October 2022, the Airbus A330-300 assigned to this route exceeded the runway limits during its landing phase in Cebu, caused by a malfunction in the hydraulic system. There were no fatalities, although 20 individuals sustained injuries.

The aircraft suffered irreparable damage and was subsequently written off, marking the 14th total loss of an Airbus A330 globally. This event also constituted Korean Air's first hull loss since the crash of Korean Air Cargo Flight 8509 in the United Kingdom almost 23 years prior.

Aircraft

The airplane involved was a 24-year-old Airbus A330-322 with serial number 219, bearing registration HL7525. Its maiden flight occurred on 12 May 1998, and it was delivered new to Korean Air on 26 June 1998. The aircraft was equipped with two Pratt & Whitney PW4168 engines.

Crew

The captain was aged 52 and had accumulated 13,043 flight hours, including 9,285 hours on the A330 type. The first officer was 37 years old and had logged 1,603 flight hours, with 1,035 hours on the A330.

Accident

Flight KE631 departed Seoul at 19:20 KST with a planned arrival at Cebu at 22:00 PHT. At approximately 22:12 PHT, during final approach to Mactan–Cebu International Airport amid scattered thunderstorms, air traffic control initially cleared the crew to land on runway 4 but subsequently redirected them to runway 22 due to changing wind conditions. While descending through heavy rain that reduced visibility, the pilots initiated a go-around. On their second landing attempt, turbulence encountered at about 300 feet caused the aircraft to drop below the glide slope; pilot overcorrections resulted in altitude instability. A rapid change from crosswind to tailwind combined with a downdraft prevented regaining proper altitude. At under 75 feet altitude, a second go-around was attempted; however, the right landing gear contacted the ground two meters before the runway threshold and sustained significant damage.

After climbing above 1,500 feet, multiple fault indicators signaled a loss of communication regarding gear status. Due to the landing gear system failure, the standard braking mechanisms—including anti-skid systems, reverse thrust, and spoilers—became inoperative; the crew engaged alternate braking systems instead. The aircraft then circled northeast of Cebu for roughly half an hour before attempting a third approach.

Prior to the accident, hydraulic fluid had been leaking within the Pressure Relief Valve (PRV) unbeknownst to both crew and maintenance personnel. With damage to the right landing gear causing external fluid leakage, the alternate braking system's effectiveness diminished. Following procedure, pilots deactivated alternate brakes and relied on emergency brakes; however, emergency brake pressure had also been depleted because of earlier leakage. Consequently, the aircraft effectively operated with minimal braking force without crew awareness.

During the third touchdown at 23:08, the aircraft failed to decelerate sufficiently and overran the runway traveling at approximately 83 knots. It collided with an instrument landing system lighting array and came to rest about 300 meters beyond the runway threshold. Witnesses noted that after stopping in marshy terrain, parts of the lighting array were positioned over the wings of the aircraft.

Meteorological data indicated a headwind of nine knots from southwest (220 degrees) during landing on runway 22. Visibility was estimated at around eight kilometers with ongoing thunderstorms and rain; cumulonimbus clouds were present at roughly 1,800 meters altitude with overcast conditions at approximately 9,000 meters above Cebu. Several other flights had diverted due to weather conditions before Flight KE631's attempts; however, their timing relative to KE631 remains unclear.

Aftermath

In the wake of the incident, flights bound for Cebu had to either return to their departure airports or divert to alternative locations such as Francisco Bangoy International Airport in Davao or Ninoy Aquino International Airport in Manila. More than 100 flights were completely cancelled.

Korean Air issued a public apology through their Instagram platform, pledging a comprehensive investigation in collaboration with both local and Korean aviation authorities to uncover the root cause.

Industry analysts raised outstanding concerns, especially regarding why the flight crew proceeded with landing attempts despite other pilots judging the conditions unsafe. Media outlets drew comparisons to prior Korean Air events involving pilot errors and the airline’s longstanding issues with safety culture.

Following a separate engine failure on another Korean Air Airbus A330 shortly after departure, the airline decided to ground its entire A330 fleet pending a thorough safety review.

On 31 October 2022, Korean Air updated the flight numbers for the Seoul–Cebu route from KE631/KE632 to KE615/KE616.

The aircraft HL7525 remained stationed at the runway’s end, stripped of its livery and logo. After two months spent constructing access roads for removal, the plane was relocated to the airfield’s southern corner, where its nearly intact fuselage still resides.

Investigation

The Civil Aviation Authority of the Philippines (CAAP) led the investigation into the accident, supported by a team of 40 officials from the Korean Office of Civil Aviation (KOCA) who arrived in Bohol shortly after the event.

Preliminary report

On 24 October 2022, Philippine authorities together with South Korea's Ministry of Land, Infrastructure and Transport (MOLIT) issued a preliminary report pinpointing hydraulic failure as the reason behind the brake malfunction.

The following day, 25 October 2022, testimony from the flight captain revealed that during their second landing attempt a hard touchdown occurred due to wind shear. During the ensuing go-around procedure, a brake warning light illuminated, leading to an emergency declaration. On their third approach, a brake pressure warning light activated and the pilots were unable to decelerate the aircraft effectively.

Interim report

CAAP released its initial interim statement on 23 October 2023, confirming that the draft investigation report was close to completion. A second interim update was issued on 22 October 2024, stating that the draft final report had been circulated among all pertinent Accredited Representatives.

Final report

The final report published by CAAP on 15 March 2025 identified three main factors during the second approach that contributed to a go-around before the successful landing:

The pilot’s forward pitch control causing premature ground contact prior to reaching the runway
An increase in vertical wind components
The right main landing gear striking a 15cm step at the runway edge, which damaged the gear and rendered most deceleration systems inoperative

Additional contributing elements included:

Failure of spoilers and thrust reversers
Malfunction within the aircraft’s brake system
Inadequacies in Airbus crew operating procedures and alerting mechanisms related to a blue hydraulic low-level fault

References