6 August 1997 - Korean Air 801

Korean Air Flight 801 (KE801, KAL801) was a scheduled international passenger flight operated by Korean Air. The flight crashed on August 6, 1997, on approach to Antonio B. Won Pat International Airport, in the United States territory of Guam, killing 229[a] of the 254 people aboard. The aircraft crashed on Nimitz Hill in Asan-Maina, Guam, while on approach to the airport. The National Transportation Safety Board cites poor communication between the flight crew as probable cause for the air crash, along with the captain's poor decision-making on the non-precision approach.

Flight 801 departed from Seoul-Kimpo International Airport (now Gimpo International Airport) at 8:53 p.m. (9:53 p.m. Guam time) on August 5 on its way to Guam. The flight experienced some turbulence, but was uneventful until shortly after 1:00 a.m. on August 6, as the jet was preparing to land. There was heavy rain at Guam so visibility was considerably reduced and the crew attempted an instrument landing. The glideslope Instrument Landing System (ILS) for runway 6L was out of service. However, Captain Park believed it was in service, and at 1:35 am managed to pick up a signal that was later identified to be from an irrelevant electronic device on the ground. The crew noticed that the aircraft was descending very steeply, and noted several times that the airport "is not in sight." Despite protests from flight engineer Nam that the detected signal was not the glide-slope indicator, Park pressed on and at 1:42 am, the aircraft crashed into Nimitz Hill, slightly south of the community of Nimitz Hill Annex, about 3 nautical miles (3.5 mi; 5.6 km) short of the runway, at an altitude of 660 feet (200 m).

The U.S. National Transportation Safety Board (NTSB) investigated the accident.

A special weather observation made at 01:32, ten minutes before the impact, reported:

Wind 090° at 6 knots; visibility—7 miles; present weather—shower vicinity; sky condition—scattered 1,600 feet, broken 2,500 feet, overcast 5,000 feet [above ground level]; temperature—27° C; dew point—25° C; altimeter setting 29.85 inches Hg; remarks—showers vicinity northwest-northeast.

Another special weather observation made at 01:47, five minutes after the impact, reported:

Wind variable at 4 knots; visibility—5 miles; present weather—light rain shower; sky condition—few 1,500 feet, scattered 2,500 feet, overcast 4,000 feet; temperature 26° C; dew point 24° C; altimeter 29.85 inches Hg.

The crew had been using an outdated flight map that was missing a 724 foot obstruction symbol depicted at the NIMITZ VOR and that map stated the Minimum Safe Altitude while crossing the NIMITZ VOR for a landing aircraft was 1,300 feet (400 m) as opposed to the updated altitude of 1,440 feet (440 m). Flight 801 crashed near the NIMITZ VOR, which is situated on Nimitz Hill at a height of 680 feet (210 m) at 1:42 am, when it descended below the minimum safe altitude of 1,440 feet (440 m) during its landing approach. The report also identified that the captain may have mistakenly believed that the airplane was closer to the airport than it was and that there may have been confusion about the location of the Distance Measuring Equipment (DME) in relation to the airport, with the crew anticipating the VOR/DME to be located at the airport. The DME was sited at the NIMITZ VOR some 3.3 nmi (3.8 mi; 6.1 km) from the airport and such a configuration had not been part of Korean Air's simulator training, the crew's training for such non-precision approaches having been carried out in scenarios where the DME was located at the airport. Nevertheless, the correct DME distances were shown on the approach chart.

The NTSB was critical of the flight crew's monitoring of the approach, and even more critical of why the first officer and flight engineer did not challenge the captain for his errors. Even before the accident, Korean Air's Crew Resource Management program was already attempting to promote a free atmosphere between the flight crew, requiring the first officer and flight engineer to challenge the captain if they felt concerned. However, the flight crew only began to challenge the captain six seconds before impact, when the first officer urged the captain to make a missed approach. According to the cockpit voice recorder (CVR), the flight crew had suggested to the captain that he made a mistake, but did not explicitly warn him. The flight crew had the opportunity to be more aggressive in his challenge and the first officer even had the opportunity to take over control of the aircraft and execute a missed approach himself, which would have prevented the accident, but he did not do this. Despite examining Korean Air's safety culture and previous incidents, the NTSB was unable to determine the exact reasons why the flight crew failed to challenge the captain, but at the same time noted that "problems associated with subordinate officers challenging a captain are well known."

Air Traffic Control error also played a role in the accident. The approach controller, 39-year-old Kurt James Mayo, did not give a position advisory to the flight crew, which would have advised them to cross check their position on radar with that of other flight instruments. In addition, he was supposed to monitor the flight even after they switched to the tower frequency, which could have allowed him to alert the rescue response. Mayo did not monitor the flight on the terminal radar display which showed the terrain in the area because radar service had been terminated at the time. The tower controller, Marty Irvin Theobald (also 39), was also criticized for not alerting the crew, as Mayo had been unaware of the aircraft's low altitude, and did not provide an alert to him.

Special Link: Radar Data with selected ATC and CVR communication excerpts

Transcript of Air Traffic communications

LEGENDA:

Guam CERAP: CERAPAgana FCT, Local Control: LCKorean Airline Flight 801: KAL801Ramp Control: RAMPAndersen AFB Control Tower: Andersen