On 6 August 1997, Korean Air flight 801, a Boeing 747-300, crashed at night at Nimitz Hill, 3 miles southwest of Won Guam International Airport, Agana, Guam while on final approach for runway 6 Left. Of the 254 persons on board, 228 were killed, and 23 passengers and 3 flight attendants survived the accident with serious injuries.
Flight 801 took off from Kimpo International Airport, Seoul, Korea at about 2153 Guam LT. The captain was the pilot flying and the first officer was performing the pilot monitoring duties. Upon arrival to the Guam area the crew was cleared to descent from FL410 to two thousand six hundred feet at own discretion.
During the approach the captain made several statements about the working time calculation and payment and that “they make us work to maximum, up to maximum...”
At about 01:24:30 the first officer requested deviation due to weather and was cleared to avoid with left turn. Six minutes later the crew requested radar vectors for runway 06 left. After initial vectoring at heading 120, the controller stated: “Korean Air eight zero one cleared for ILS runway six left approach…glideslope unusable.” The first officer responded: “Korean eight zero one roger…cleared Instrument Landing System (ILS) runway six left.”; he did not acknowledge that the glideslope was unusable.
According to the CVR, at about 01:39:55 the flight engineer asked, “is the glideslope working? glideslope? yeh?” One second later, the captain responded, “yes, yes, it’s working.”
At about 01:40:42 the flight was transferred to Agana control tower. The tower controller cleared flight 801 to land. During the following descent GPWS/TAWS activated several times providing either altitude or sink rate warning. At about 01:42:19, as the airplane descended through 730 feet msl, the first officer followed by the flight engineer, both declared they did not have visual contact with the runway and proposed missed approach. Four (4) seconds later the captain stated ‘go around’ and the engine pressure ratios and air-speed began to increase. The rate of nose-up control column deflection remained about 1° per second. About 01:42:26, the airplane impacted hilly terrain at Nimitz Hill, Guam.
The investigation concluded on the probable cause as follows:
The National Transportation Safety Board determined that the probable cause of this accident was the captain’s failure to adequately brief and execute the non-precision approach and the first officer’s and flight engineer’s failure to effectively monitor and cross-check the captain’s execution of the approach. Contributing to these failures were the captain’s fatigue and Korean Air’s inadequate flight crew training.
Contributing to the accident was the Federal Aviation Administration’s intentional inhibition of the minimum safe altitude warning system at Guam and the agency’s failure to adequately manage the system.
As a result of the investigation the National Transportation Safety Board (NTSB) made recommendations to the following parties concerned:
- Federal Aviation Administration. Recommendations include, but are not limited to: possible designation of Guam International Airport as a special airport requiring special pilot qualifications; ensuring that full briefing is performed by air carrier pilots with instrument approach included as back up; information dissemination about the possibility of momentary erroneous indications on cockpit displays when the primary signal generator for a ground-based navigational transmitter is inoperative. Recommendations were made also on the matter of: pilot training of
non-precision approaches and flying with constant angle of descent by cross-referencing the distance from the airport and the barometric altitude; ATC staff mandatory briefing of accident circumstances and plans for installation of on-board navigational system with enhanced functionalities.
- The Governor of the Territory of Guam. Formation of task force to define and coordinate emergency notifications was recommended. The requirement to perform periodic disaster response exercises was also added.
- The Korean Civil Aviation Bureau. A revision of Korean Air video presentation for Guam was recommended “…to emphasize that instrument approaches should also be expected and describe the complexity of such approaches and significant terrain along the approach courses and in the vicinity of the airport.”