Korean Air Cargo Flight 8509

Korean Air Cargo Flight 8509 was a Boeing 747-2B5F, registered HL7451 bound for Milan 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, killing all four crew members on board.

Flight crew

The flight crew consisted of:

57-year-old Captain Park Duk-kyu

33-year-old First Officer Yoon Ki-sik

38-year-old Flight Engineer Park Hoon-kyu

45-year-old maintenance mechanic Kim Il-suk.

The captain was a former colonel 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. The maintenance mechanic had been involved with the failed INU repair.

Accident

It was dark when the plane took off from London Stansted Airport, with the captain flying. The aircraft entered the clouds 400 feet above the terrain. When the captain banked the plane to the left, the faulty INU sent erroneous data to his ADI, preventing the instrument from showing the aircraft was in a bank. The comparator alarm sounded repeatedly, which was an indication that the aircraft's two ADI displays were in disagreement. The first officer, whose own ADI displayed the correct angle of bank, according to information from the aircraft's flight data recorder, failed to participate in full crew resource management techniques, saying nothing to challenge his captain's actions nor making any attempt to take over the flight with his own controls. The older and more experienced flight engineer did call out "Bank is not working" (translated into English from Korean in the AAIB report) 20.8 seconds before impact, "Bank Bank" (in English) 16.9 seconds before impact, "Standby indicator [in English] also not working [in Korean]" 10.2 seconds before impact, and "Oy!, bank." (in Korean) 1.5 seconds before impact. The captain continued to ignore the chiming alarm and made no verbal response to the flight engineer. Data from the flight recorder indicate that during this time the control wheel was commanding the aircraft into a steeper left bank. 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 kn, in a 40° pitch down and 90° left bank attitude. The aircraft exploded on impact.