NTSB Identification: OPS03IA001.
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Incident occurred Tuesday, December 17, 2002 in Agana, GU
Probable Cause Approval Date: 02/05/2004
Aircraft: Airbus Industrie 330-301, registration:
Injuries: 115 Uninjured.
NTSB investigators used data provided by various sources and may have traveled in support of this investigation to prepare this aircraft incident report.
The Philippine Airlines Airbus A330 began an instrument landing system (ILS) approach to runway 6L at A.B. Won Pat Guam International Airport. According to flight data recorder information and the captain's statement, the captain set the autopilot to fly a 3.4 degree descent angle as the aircraft descended through 3,600 feet. At that point, the aircraft was 12.7 miles from the runway 6L touchdown point, where the calculated glideslope height based on the 3.0 degree glideslope specified on the ILS 6L approach chart is 4,060 feet. Therefore, the aircraft began its approach from a position 460 feet below the glideslope at an angle that was 0.4 degrees steeper than the standard glideslope. This resulted in a descent path that ended at the top of Nimitz Hill, approximately 4.5 miles from the runway 6L touchdown point. The airplane struck power lines at the hilltop, which is located about one mile from the site of a fatal accident involving a Korean Airlines (KAL) Boeing 747 that occurred in 1997. The crew then responded to a ground proximity warning system(GPWS) alert and began a climb, returning for another approach. The Guam air traffic control radar system generated a minimum safe altitude warning (MSAW) alert to the radar controller at 17:34:25 that continued for 1 minute and 22 seconds and ended at 17:35:47. During this period, the aircraft descended from approximately 1,700 feet to approximately 700 feet, and then began climbing in response to the GPWS alert. The controller took no action to warn the crew or the GUM tower controller about the aircraft's MSAW alert status or proximity to terrain. After the 1997 KAL accident, the Safety Board recommended that the FAA consider designating Guam International Airport as a special airport requiring special pilot qualifications. At this time, that recommendation is classified as "Open - Acceptable Action" by the Safety Board.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: The pilot's initiation of a premature descent that was both below the nominal glideslope and steeper than normal. Contributing to the incident was the air traffic controller's failure to respond to the MSAW warning and issue a safety alert as required by FAA order. Full narrative available
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