# NTSB OPS03IA001: Airbus Industrie 330-301, Agana, December 17, 2002 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: December 17, 2002, 03:35 local (11:35 UTC) - Place: Agana - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 115 uninjured - Status: Completed, report February 5, 2004 - Report: Approved by Office Director - NTSB office: Operational Factors Division - Parties: Washington DC HQ (AAI-100), NATCA - Safety recommendations: Yes - NTSB case key (mKey): 56253 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=OPS03IA001 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/56253/pdf - Page: https://openairdocs.org/ntsb/OPS03IA001 ## Probable cause 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. ## Analysis 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. ## Factual narrative HISTORY OF FLIGHT On December 16, 2002, approximately 1735 coordinated universal time (UTC), an Airbus A330, Philippine registration F-OHZO, operating as Philippine Airlines flight 110 (PAL110), struck power lines while executing a localizer-only Instrument Landing System (ILS) approach to runway 6L at A.B. Pat Won Guam International Airport, Agana, Guam (GUM). Instrument meteorological conditions prevailed during the approach. Following a ground proximity warning system (GPWS) alert, the crew executed a missed approach and landed successfully after a second approach to the airport. The aircraft remained on the ground at Agana until departing at 2115 UTC to return to Manila as PAL flight 111. According to information provided by Philippine Airlines, after arriving at Manila the aircraft was inspected and found to have minor damage to the fuselage and landing gear. There were no reported injuries to passengers or crew. The flight was operated under Title 14, Code of Federal Regulations Part 129 as a scheduled passenger flight from Ninoy Aquino International Airport (MNL), Manila, Philippines, to GUM. At the time of the incident, the GUM Automatic Surface Observation System (ASOS), ILS 6L glideslope, middle marker, and approach light system were all out of service because of typhoon damage, as was the Nimitz Very High Frequency Omnirange (UNZ VOR). Because of these outages, Guam Combined Center-Radar Approach Control (CERAP) was clearing aircraft for localizer-only ILS approaches to runway 6L. The pilot of PAL110 first contacted Guam CERAP at 1654:08, stating "Guam Center, Philippine one ten." The CERAP controller asked the pilot to confirm that the aircraft was at flight level 370, and assigned the flight beacon code 2151. The crew acknowledged. At 1702:19, the controller advised the crew, "Radar contact seventy miles southeast of KITSS cleared direct IKOVY expect localizer approach." The pilot responded, "OK direct IKOVY and expect 06 localizer Philippine one one zero." At 1706:52, the controller cleared the pilot of PAL110 to, "descend at pilot's discretion, maintain twenty six hundred, advise information India, Agana altimeter two nine nine nine." The pilot acknowledged the altitude assignment and confirmed that he had received information India. At 1708:00, the pilot reported that PAL110 was leaving flight level 370 for 2,600 feet and the controller acknowledged. At 1720:14, the pilot of PAL110 transmitted, "Philippine one ten confirm we're landing runway six left?" The controller responded, "Affirmative, runway six left is in use at Agana." At 1720:29, the controller transmitted, "Philippine one ten cross IKOVY at or above two thousand six hundred cleared ILS six left glideslope unusable." The pilot read back, "OK cross IKOVY at or above two thousand six hundred cleared ILS six left glideslope unusable Philippine one ten." The controller then acknowledged and added, "and DME is also out of service." The pilot acknowledged. (Subsequent investigation showed that the DME was unmonitored rather than out of service, so the controller's advisory was incorrect.) At 1728:39, the CERAP controller called the GUM tower controller to coordinate PAL110's arrival, stating that the aircraft was "twenty five east Philippine one ten heavy Airbus." The tower controller responded, "Who was it?" and the CERAP controller repeated, "Philippine one ten." The CERAP controller then added, "for the ILS six left rw bc." (Controllers use "operating initials" to identify themselves during interphone conversations. The GUM tower controller's operating initials are RW, and the CERAP controller uses BC.) At 1728:59, the CERAP controller transmitted, "Philippine one ten established on the localizer inbound contact Agana tower good day." The pilot acknowledged. According to flight data recorder position information, the aircraft was 23.8 miles from the runway 6L threshold, descending through 5,700 feet. At 1729:20, the pilot of PAL110 transmitted, "Guam tower, aah, good morning, Philippine one one zero with huh leaving five thousand five hundred." The GUM tower controller responded, "Philippine one one zero Agana tower roger sir. Runway six left cleared to land, wind one zero zero at six." The pilot read back, "Cleared to land runway six, Philippine one one zero." While PAL110 was on approach to GUM, the CERAP controller was also handling Reach 8223, an arrival to Andersen AFB. At 1734:24, the CERAP controller transmitted, "Reach 8223 heavy fly heading two eight zero vectors tacan final." At 1734:26, during the transmission to Reach 8223, an aural MSAW alert is audible in the background. According to recorded MSAW activation data, the first alert for PAL110 activated at 1734:25 and would have produced a two second aural alert tone at the R4 position. Following the transmission to Reach 8223, the CERAP controller contacted Andersen tower to coordinate the arrival and then continued handling that aircraft. At 1735:46, there was a brief sound of a transmitter keying on the GUM tower frequency, but no voice. At 1736:15, the pilot of PAL110 reported to GUM tower, "Philippine one one zero making missed approach." The tower controller replied, "Philippine one one zero Agana tower, roger sir, fly runway heading, climb and maintain two thou, correction, two thousand five hundred contact Guam Departure one eighteen seven." At 1736:28, the pilot read back, "OK, two thou (garbled), Philippine roger." The GUM tower controller immediately called the CERAP and reported, "Philippine one ten missed." The CERAP controller replied, "Really? You're kidding. Your weather that bad?" The tower controller stated, "I don't think it's that bad. It looks pretty clear to me official weather showing six miles visibility." The CERAP controller then said, "OK runway heading climbing to four thousand." Neither controller evidenced any awareness of the MSAW alert or the aircraft's proximity to Nimitz Hill. At 1736:52, the tower controller transmitted, "Philippine one one zero, tower. You still up freq?" The pilot responded, "Say again, sir?" The tower controller replied, "Roger sir, continue runway heading climb and maintain four thousand, contact Guam departure one eighteen seven." The pilot read back, "OK, four thousand, one eighteen seven, Philippine one one (garbled) switching." At 1737:30, the pilot of PAL110 transmitted to Guam CERAP, "Philippine one ten with you passing three thousand one hundred." The CERAP controller responded, "Philippine one ten roger turn right heading one eight zero vectors ILS approach." At 1739:04, the pilot of PAL110 reported level at 4,000 feet and heading 180. The CERAP controller responded, "Philippine one ten roger turn right heading two four zero." The pilot acknowledged. At 1740:44, the CERAP controller transmitted, "Philippine one ten descend and maintain two thousand six hundred." The pilot replied, "Descend and maintain two thousand six hundred Philippine one ten." At 1742:32, the CERAP controller transmitted, "Philippine turn right heading three three zero." The pilot of PAL110 responded, "right three three zero Philippine one ten." At 1743:13, the controller instructed the pilot of PAL110 to, "turn right heading three zero zero." The pilot acknowledged the heading assignment, and then asked, "is that three zero zero or two three zero?" The controller replied, "Correction the heading is three five zero Philippine one ten." The pilot acknowledged. At 1743:46, the CERAP controller issued PAL110's second approach clearance, stating, "Philippine one ten heavy position is five miles west of final approach fix, fly heading zero three zero maintain at or above two thousand until established on final cleared for ILS runway six left approach." The pilot read back, "OK zero three zero maintain two thousand until established on final cleared for ILS six left approach." At 1744:31, ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, approach - iaf to faf/outer marker (ifr) - object - wire,transmission - proper glidepath - not attained, flightcrew (cause) - safety advisory - not issued, atc personnel(artcc) (cause) ## Aircraft - Registration: F-OHZO (not matched to a registry record) - Reported make and model: Airbus Industrie 330-301 - Category: Airplane - Serial number: MFR #188 - Engines: General Electric CF6 turbo fan - Damage: Minor damage - Flight: Part 129 - Operator: Philippine Airlines - Registered owner: Credit Lyonnais - Airworthiness certificate: Standard, Transport - Departed: MNL, Manila - Destination: GUM, Agana - Flight plan: IFR - Airport: PGUM, Guam International, runway 6L, 10,015 × 150 ft, concrete ## Weather - Conditions: Instrument (IMC), Night/dark - Lowest ceiling: 200 ft indefinitevv - Observed at: PGUM, 5 nm away From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.