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A333, vicinity Wom Guam Airport, Guam, 2002

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Summary
On 16 December 2002, approximately 1735 UTC, an Airbus A330-330, operating as Philippine Airlines flight 110, 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. 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.
Event Details
When December 2002
Actual or Potential
Event Type
CFIT, HF
Day/Night Night
Flight Conditions IMC
Flight Details
Aircraft AIRBUS A-330-300
Operator Philippine Airlines
Domicile Philippines
Type of Flight Public Transport (Passenger)
Origin Manila/Ninoy Aquino International Airport
Intended Destination Guam
Actual Destination Guam
Flight Phase Missed Approach
APR
Location - Airport
Airport vicinity Guam
General
Tag(s) Non Precision Approach
CFIT
Tag(s) Into terrain
No Visual Reference
Vertical navigation error
IFR flight plan
HF
Tag(s) Distraction
Ineffective Monitoring
Data use error
Procedural non compliance
Inappropriate ATC Communication
Safety Net Mitigations
Malfunction of Relevant Safety Net No
GPWS Effective
MSAW Available but ineffective
Outcome
Damage or injury Yes
Aircraft damage Minor
Causal Factor Group(s)
Group(s) Aircraft Operation
Air Traffic Management
Safety Recommendation(s)
Group(s) None Made
Investigation Type
Type Independent

Description

On 16 December 2002, approximately 1735 UTC, an Airbus A330-330, 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.

At the time of the incident, Guam Combined Center-Radar Approach Control (CERAP) was clearing aircraft for localizer-only ILS approaches to runway 6L. 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 (UNZ) VOR.

As the aircraft was passing 3,600 ft1,097.28 m, the captain set the autopilot to fly a 3.4° descent angle, 0.4° steeper than the standard glideslope. The latter, combined with the fact that the aircraft was 460 feet below the glideslope resulted in a descent path that ended 4.5 nm8,334 m
8.334 km
27,342.52 ft
from the runway 6L touchdown point, in the area of Nimitz Hill. The airplane struck power lines at the hilltop. The crew then responded to a ground proximity warning system (GPWS) alert and began a climb, returning for another approach

The Investigation

The National Transportation Safety Board determines the probable cause(s) of this incident as follows:

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.

The following recommendation was made:

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.

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