Korean Air Cargo Flight 8509

Korean Air Cargo Flight 8509 was a Boeing 747-2B5F, registered HL7451 and bound for Milano-Malpensa Airport, that crashed due to instrument malfunction and pilot error on 22 December 1999 shortly after take-off from London Stansted Airport where the final leg of its route from South Korea to Italy had begun. The aircraft crashed into Hatfield Forest near the village of Great Hallingbury, close to but clear of some houses. All four crew on board died.[2][1].

Korean Air Cargo Flight 8509
A large cargo aircraft in the colours of Korean Air Cargo
The 747 involved in the accident, in 1992.
Date22 December 1999
SummaryCrash on takeoff due to instrument malfunction[1]
SiteGreat Hallingbury, England, United Kingdom
51°51′23″N 0°12′59″E / 51.85639°N 0.21639°E / 51.85639; 0.21639Coordinates: 51°51′23″N 0°12′59″E / 51.85639°N 0.21639°E / 51.85639; 0.21639
Aircraft typeBoeing 747-2B5F
OperatorKorean Air Cargo
Flight originGimpo International Airport, Seoul, South Korea
1st stopoverTashkent International Airport, Tashkent, Uzbekistan
2nd stopoverLondon Stansted Airport, England, United Kingdom
DestinationMalpensa Airport, Milan, Italy

The aircraftEdit

The aircraft involved was a 19-year-old Boeing 747-200F freighter registered HL7451. First flown on 4 April 1980, the aircraft had completed 15,451 flights with a total flight time of 83,011 hours before its fatal flight.[2][3][4]

INU failure and failed repairEdit

Following the plane's departure from Tashkent on the previous flight segment, one of its inertial navigation units (INUs) had partially failed, providing erroneous roll data to the captain's attitude director indicator (ADI or artificial horizon). The first officer's ADI and a backup ADI were correct, a comparator alarm called attention to the discrepancy, and in daylight the erroneous indication was easily identified. The ADI's input selector was switched to the other INU and the correct indications returned.[2]

At Stansted, the engineers who attempted to repair the ADI did not have the correct Fault Isolation Manual available and did not think of replacing the INU. One of them identified and repaired a damaged connecting plug on the ADI. When the ADI responded correctly to its "Test" button, they believed the fault had been corrected, although this button only tested the ADI and not the INU. The ADI's input selector was left in the normal position.[2]

Flight crewEdit

The flight crew consisted of 57-year-old Captain Park Duk-kyu (Hangul: 박득규, Hanja: 朴得圭, RR: Bak Deuk-gyu, M-R: Pak Tŭkkyu), 33-year-old First Officer Yoon Ki-sik (Hangul: 윤기식, Hanja: 尹基植, RR: Yun Gi-sik, M-R: Yun Kishik), 38-year-old Flight Engineer Park Hoon-kyu (Hangul: 박훈규, Hanja: 朴薰圭, RR: Bak Hun-gyu, M-R: Pak Hun'gyu), and 45-year-old maintenance mechanic Kim Il-suk (Hangul: 김일석, Hanja: 金日奭, RR: Gim Il-seok, M-R: Kim Ilsŏk).[5][6] The captain was a former colonel and pilot in the Republic of Korea Air Force and a highly experienced airman,[7] with a total of 13,490 flying hours – 8,495 of which were accumulated flying Boeing 747s. The first officer, in contrast, was relatively inexperienced with just 195 hours of flying experience on the 747 and a total of 1,406 flight hours. The flight engineer, like the captain, had a lot of experience flying 747s – 4,511 out of his 8,301 total flight hours were accrued in them. The maintenance mechanic had been involved with the failed INU repair.[7]


It was dark when the plane took off from London Stansted Airport, with the captain flying.[7] When the captain tried to bank the plane to turn left, his ADI showed it not banking, but the comparator alarm sounded repeatedly.[7] The first officer, whose own ADI would have shown the true angle of bank, failed to participate in full crew resource management techniques, saying nothing to challenge his captain's actions nor made any attempt to take over the flight with his own controls. The older and more experienced flight engineer did call out "Bank!, Bank!, Look!, Bank!"[8] in 19 seconds, but the captain ignored his warnings, continued to ignore the chiming alarm,[2] made no verbal response, and actually continued to increase the left bank angle.[7] At 18:38, 55 seconds after take-off, Flight 8509's left wing dragged along the ground, then the aircraft plunged into the ground at a speed of between 250 and 300 knots[citation needed], in a 40° pitch down and 90° left bank attitude.[2] The aircraft exploded on impact.[7]


After the investigation, the United Kingdom's Air Accidents Investigation Branch (AAIB) issued recommendations to Korean Air to revise its training program and company culture, to promote a more free atmosphere between the captain and the first officer.[7] The first recommendation of the AAIB's final accident report was that:

Korean Air continue to update their training and Flight Quality Assurance programmes, to accommodate Crew Resource Management evolution and industry developments, to address issues specific to their operational environment and ensure adaptation of imported training material to accommodate the Korean culture.[2][9]

The AAIB also recommended the airline to review its maintenance procedures. The second and third recommendations are that:

Korean Air continue to review its policy and procedures for maintenance support at international destinations with a view to deploying sufficient of its own full-time engineers at the outstation or delegating the entire task to another operator or third-party maintenance organisation locally-based at the destination (Full Technical Handling). If neither of these approaches is practicable then the support arrangements must be detailed and of such clarity as to preclude confusion. Korean Air review its policy and procedures to ensure that a copy of the relevant pages of the Technical Log and any other transit certification documents are left on the ground at the point of departure.[2]

In popular cultureEdit

A March 2012 episode of Mayday also called Air Crash Investigation in the U.K. and the rest of the world (Season 11 Episode 7) titled "Bad Attitude" or "Stansted Crash" investigates this accident.[7]

See alsoEdit


  1. ^ a b "Korean Air Cargo Flight 8509 incident report". Aviation Safety Network. Retrieved 10 July 2011.
  2. ^ a b c d e f g h "Report on the accident to Boeing 747-2B5F, HL-7451 near London Stansted Airport on 22 December 1999" (PDF). Air Accident Investigation Branch. June 2003. Archived (PDF) from the original on 8 June 2012. Retrieved 10 July 2011.
  3. ^ "HL7451 Korean Air Lines Boeing 747-200". www.planespotters.net. Retrieved 27 June 2020.
  4. ^ "Korean Air HL7451 (Boeing 747 - MSN 22480)". www.airfleets.net. Airfleets aviation. Retrieved 27 June 2020.
  5. ^ Byrne, Caroline (23 December 1999). "Korean Air Faces Crackdown After 4 Die In London Crash". The Seattle Times. Associated Press. Retrieved 3 January 2012.
  6. ^ "[KAL화물기 추락]英서 이륙2분만에…승무원 4명 모두 사망" [[KAL Freighter crashed] 2 minutes after taking off from British... All four crew members died]. The Dong-a Ilbo (in Korean). 23 December 1999. Archived from the original on 2 January 2014. 이 사고로 기장 박득규(朴得圭·57)씨, 부기장 윤기식(尹基植·33)씨, 항공기관사 박훈규(朴薰圭·38)씨, 정비사 김일석(金日奭·45)씨 등 한국인 승무원 4명이 모두 숨졌다. [English: All four Korean crew members died in the accident, including Captain Park Deuk-kyu (박·57), Deputy General Manager Ki-sik Yoon (33), Aircraft Engineer Park Hun-kyu (朴薰圭·38), and mechanic Kim Il-suk (金日奭·45)]
  7. ^ a b c d e f g h "Bad Attitude". Mayday. Season 11. Episode 7. March 2012.
  8. ^ Cite error: The named reference Air Disasters was invoked but never defined (see the help page).
  9. ^ "Report appendices" (PDF). Air Accident Investigation Branch. Retrieved 30 June 2019.

External linksEdit