F-OHZO
Airbus Industrie 330-301
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.
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, the CERAP controller advised the GUM controller that, "Philippine is on the ILS again." At 1745:25, the pilot of PAL110 reported, "Philippine established on the final now runway in sight." The controller then asked, "Philippine one ten you want to fly the visual now?" The pilot replied, "affirm," and the controller responded, "Cleared for the visual approach runway six left contact Agana tower." At 1745:41, the pilot of PAL110 again contacted the tower, stating, "Hello tower, good morning, Philippine one one zero we're six miles on final, runway in sight, visual." The tower controller responded, "Philippine one one zero Agana tower, roger sir, runway six left cleared to land, wind zero niner zero at six." The pilot read back, "Cleared to land six left, Philippine one one zero." At 1748:29, the tower controller instructed the pilot of PAL110 to, "turn left pilot discretion, contact Ramp Control one two one point six, good morning." The pilot responded, "one two one point six, good morning." There were no further ATC contacts with the flight. Safety Board and FAA investigators inspected the Nimitz Hill area on January 5, met with four witnesses, and examined the area surrounding their residences. Because of the December typhoon, the island's power transmission systems were heavily damaged. The wires reportedly knocked down by PAL110 were still not repaired because of the higher priority repairs being undertaken elsewhere on the island. Of the original three wires attached to the pole adjacent to the witness residences, two were snapped and one was dislodged from the pole. Three of the witnesses live in a house located directly beneath the ILS 06 final approach course and approximately 1/2 mile inside the outer marker (OM). On the night of the incident, they were asleep in different rooms. Witness 1's room is located in the southwest corner of the house, with one window facing the outer marker and another facing perpendicular to the final approach course. He stated that he was awakened by an unusual noise at about 3:30 A.M. local time. While lying in bed, witness 1 looked out the window on the southwest side (toward the OM) but didn't see anything. He then looked out through the window on the southeast side of the building and stated that he "…saw an entire airplane go by. The house shook, and it was very bright outside." He also heard "two distinct snapping sounds." Witness 1 reported that he then ran to the northeast side of the house, expecting to see a crash, but instead saw a jet pitching up and disappearing into the clouds. Witness 2 did not see the jet approaching or passing by the house, but reported being awakened by the noise and vibration. She also ran to the side of the house where she encountered witness 1, who described what he had seen. Witness 3 also heard and felt the aircraft pass by the house, stating that "the whole house was shaking." In the morning, witness 2 found snapped power lines on the ground in front of her house, and noticed that the power pole had a broken crossbar that had remained intact following the typhoon of the previous week. At about 0700 she telephoned Guam CERAP to report that she believed an aircraft had struck the wires and almost struck her house, but had difficulty convincing the supervisor on duty that a serious incident had occurred. She was later contacted by the CERAP air traffic manager to discuss the report. Witness 4, an airline captain, lives in a house located about 150 feet southwest of the residence occupied by the other witnesses. He reported that he and his wife were awakened at about 3:30 A.M. local time by what sounded like a jet passing over and very close to their house. He thought it sounded like the engines were at full power. He did not actually see the jet, but he did look outside after it passed and estimated that the cloud ceiling over the hill was 200 to 300 feet above the ground. He telephoned GUM ATCT at about 2 P.M. local time to inquire about the incident, but the controller on duty had no information about any unusual events during the night. While on the ground at Agana, PAL110 was serviced by staff from Airports Group International. Safety Board and FAA investigators interviewed the manager of the AGI service facility at GUM, the ramp supervisor, the maintenance supervisor, and the mechanic responsible for services provided to PAL110 on the night of the incident. All four were interviewed together to provide information on the ground handling and condition of PAL110 during its Guam turnaround. The ramp supervisor stated that the aircraft arrived at the gate at about 0340 local time. The AGI mechanic contacted the cockpit crew via headset immediately after their arrival, and stated that the crew reported no problems with the aircraft. The ramp crew immediately noticed a 3" dent and some scratches on the lower half of the bulk cargo door. They did not attempt to open the door, and called the AGI mechanic to come inspect it. The PAL flight mechanic came off the aircraft, and the AGI mechanic pointed out the damage. The PAL flight mechanic spoke only Tagalog, so they were unable to specifically discuss the dent, but the AGI mechanic stated that the PAL mechanic acknowledged the damage with a nod and a "thumbs up," which the AGI mechanic took to mean that the damage was known to the crew. Later, the AGI mechanic inspected the aircraft logbook and noted an entry about the bulk door, which was carried over as a deferred maintenance item from a previous flight. Log entries on PAL aircraft are often partially in English and partially in Tagalog: the AGI mechanic said that if he has any doubts about a particular entry, he asks a bilingual member of the flight or cabin crew to translate for him. The AGI mechanic performed a walkaround inspection of the aircraft with a flashlight, but did not notice any of the damage shown in the photos sent by PAL from Manila the following day. The photos did cover areas such as the hydraulic lines that the AGI mechanic and the maintenance supervisor stated are routinely examined as part of the inspection process. One of the photos also showed the previously logged dent. The AGI mechanic initially said that he didn't believe that the other damage was on the aircraft, but later stated that he could have overlooked it as pre-existing wear that could be considered normal for an older aircraft. He saw the PAL mechanic and one of the crewmembers do a preflight inspection before departure, and they did not point out or report any problems to him at that time. The AGI mechanic had no other contact with the crew during their ground time; he stated that the flight crew usually naps aboard the aircraft until shortly before departure time. The ground crew did not attempt to open the bulk cargo door until they needed to load some last-minute bags and miscellaneous cargo items just before departure. They were unable to operate the door, so the remaining items were loaded through the aft cargo door instead. Other than the difficulty with the bulk door, there were no unusual events affecting the aircraft during its ground time. AGI does not maintain any general logs about aircraft serviced unless specific maintenance activities occur that need to be tracked. This was a normal and routine turnaround, so nothing needed to be logged. The AGI mechanic did not see the crew do any unusual inspections or other activities while PAL110 was on the ground, other than their normal preflight. He did not overhear any comments about a go-around but noted that the crew's conversations are normally conducted in Tagalog, which he does not understand. The AGI mechanic and the maintenance supervisor noted that local contract maintenance staff do not direct maintenance actions: they bring observed abnormalities, if any, to the attention of the PAL flight mechanic, he discusses them with the crew, and they decide how to proceed. The chief pilot of PAL came to Guam on December 24th and discussed the incident with the ramp supervisor and the AGI mechanic. According to the AGI staff, he was particularly interested in the aircraft's appearance and condition when it arrived on the night of the incident. PERSONNEL INFORMATION The flight crew of PAL110 consisted of a captain, f
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.
Source: NTSB Aviation Accident Database
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