Korean Air Cargo Flight 8509
The 747 involved in the accident stands at Paris Charles de Gaulle Airport in 1992.
|Date||22 December 1999|
|Summary||Instrument malfunction, pilot error, spatial disorientation|
|Site||Great Hallingbury, England, United Kingdom
|Aircraft type||Boeing 747-2B5F|
|Operator||Korean Air Cargo|
|Flight origin||Gimpo International Airport, Seoul, South Korea|
|1st stopover||Tashkent International Airport, Tashkent, Uzbekistan|
|2nd stopover||London Stansted Airport, England, United Kingdom|
|Destination||Malpensa Airport, Milan, Italy|
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. The aircraft crashed into Hatfield Forest near the village of Great Hallingbury close to but clear of some local houses. All four crew on board were killed.
The aircraft involved was a Boeing 747-2B5F freighter registered HL7451. Built on 4 April 1980, the aircraft had completed 15,451 flights with a total flight time of 83,011 hours before its fatal flight on 22 December 1999.
INU failure and failed repair
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.
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.
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). The captain was a former Colonel (Korean: Daeryeong) and pilot in the Republic of Korea Air Force and a highly experienced airman, 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.
It was dark when the plane took off from London Stansted Airport, with the captain flying. When the captain tried to bank the plane to turn left, his ADI showed it not banking and the comparator alarm sounded repeatedly. The first officer, whose instrument would have shown the true angle of bank, said nothing, although the flight engineer called out "bank."  The captain made no response and continued banking farther and farther left. At 18:38, 55 seconds after take-off, Flight 8509's wing dragged along the ground, then the aircraft plunged into the ground at a speed between 250 and 300 knots, in a 40° pitch down and 90° left bank attitude. The aircraft exploded on impact.
After the investigation, Air Accidents Investigation Branch of the United Kingdom 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. Korean Air has not had a single fatal crash since this accident in 1999.
- Air India Flight 855
- Copa Airlines Flight 201
- United Airlines Flight 2885, a cargo flight that banked and crashed on takeoff due to pilot error
In popular culture
- A March 2012 episode of Mayday (Season 11 Episode 7) titled "Bad Attitude" investigated this accident.
- "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. Retrieved 10 July 2011. (Archive)
- "Korean Air Cargo Flight 8509 incident report". Aviation Safety Network. Retrieved 10 July 2011.
- Byrne, Caroline. "Korean Air Faces Crackdown After 4 Die In London Crash." Associated Press at the Seattle Times. Thursday 23 December 1999. Retrieved on 3 January 2012.
- "[KAL화물기 추락]英서 이륙2분만에…승무원 4명 모두 사망" (Archive). Donga Ilbo. 23 December 1999. Modified 23 September 2009. "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."
- "Bad Attitude". Mayday. Season 11. Episode 7. March 2012.
- "The AAIB interim report" – BBC – Friday 24 December 1999 (Archive)
- "AAIB Bulletin S2/2000 SPECIAL." Air Accidents Investigation Branch
- Cockpit Voice Recorder transcript and accident summary
- Boeing Expresses Condolences After Korean Air Crash – Boeing
- Boeing to Assist in Korean Air Investigation – Boeing
- "KE-8509 Crash May Be Due to Instrument Failure." – The Chosun Ilbo
- "KAL Team Joins Flight KE-8509 Investigation." – The Chosun Ilbo