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 the time of the accident stated that the D-BRITE radar display was operational but had not been certified for use. (At the time of the accident, the associated control panels for configuring the Guam tower D-BRITE video maps and settings were located at the Andersen AFB tower. According to the FAA, the equipment at the Agana tower was not certified or commissioned for use because of missing hardware and computer software.) The tower controller stated that the display showed secondary radar targets but that the radar setting selected by the Andersen AFB controllers determined whether Mode C targets would be displayed. He said that the controllers at Guam were not able to determine an airplane's position on the video map because it did not depict any final approach courses or runway orientations for the airport.

By December 1997, the two D-BRITE systems had been tested, and the Agana tower controllers received training on the systems' operation. The D-BRITE systems were certified and commissioned for use on April 11, 1998. The video map has been modified to depict the airport with extended centerlines for both runways 6L and 6R, and the system is controlled at the Guam tower.

The Agana tower controller on duty at the time of the accident told Safety Board investigators that he arrived for duty about 2215 on August 5, 1997. After that time, he and the controller on duty performed a position relief briefing, which covered airport conditions, navigation aid conditions, traffic clearances that had been issued, and the facility equipment status. After midnight, the controller performed daily administrative duties. The controller said that he was working at the local control position, which was located in the center of the tower cab facing the runway. The controller also stated that he was aware of the NOTAM regarding the out-of-service glideslope.

The tower controller said that, when Korean Air flight 801 made initial radio contact (about 0140:55), it was the only airplane that he was controlling. The tower controller said that, when flight 801 did not visually appear within 3 to 4 minutes after the airplane was cleared to land (about 0141:01), he commenced a communications search for the aircraft. The controller attempted to contact flight 801 about 0145:13 and 0150:06. Between about 0150:00 and 0151:00, the tower controller queried the CERAP controller, the ramp controller, and an Andersen AFB controller about flight 801.

FAA Form 6030-1, "Air Traffic Control Facility Maintenance Log," for July 7, 1997, showed that the Agana tower had been notified by an FAA maintenance technician that the glideslope portion of the ILS would be out of service starting that day for extensive reconstruction. The reconstruction work included the replacement of the glideslope's equipment shelter and all cabling and the upgrade of the power systems and grounding. A NOTAM issued by the FAA on July 7, 1997, indicated that the glideslope would remain out of service until September 12, 1997. The complete ILS system was