The International Society of Air Safety Investigators
VOLUME 10, NO.2 WINTER, 1977
PROCEEDINGS
of the
EIGHTH INTERNATIONAL SEMINAR
3-6 OCTOBER 1977
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THE ACCREDITED REPRESENTATIVE
William L. Lamb
CHIEF, FIELD INVESTIGATIONDIVISION
BUREAU OF ACCIDENT INVESTIGATION
NATIONAL TRANSPORTATION SAFETY BOARD
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The investigation of the Pan American World Airways, Boeing 707-321 accident on the island of Bali, Indonesia, illustrates the role of the accredited representative, and how I tdiffers from the role I normally held-Investigator-in-Charge. I was the United States accredited representative, and I hope that this .saga of my adventures-and mis-adventures may throw some light on the differences between the roles of the IIC and the accredited representative.
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Pan American Flight 812 was a scheduled international flight from Hong Kong to Sydney, with an en route stop at Denpasar, Bali. The flight departed Hong Kong at 1108Z, with an estimated en route time of 4 hours 23 minutes. The flight was routine except for difficulty in establishing radio contact with Bali approach control. Communications were established and the flight was cleared to descend from its cruising flight level of 350 to flight level 100. The flight contacted Bali Tower at flight level 110 and requested a lower altitude; seconds later, it reported over the station. This report was made at 1519; although a corrected ETA of 1527Z had been reported a few minutes before the aircraft began to descend. The 8-minute early arrival should have been a cue to the crew to verify their position. The flight was cleared to descend to 2,500 feet and landing instructions for runway 09 were issued. Shortly before 1527Z , the crew reported level at 2,500 feet and were instructed to report the runway in sight. At 1527, the crew asked,"Hey Tower, what's your visibility out there now." This was the last radio transmission from the aircraft. The wreckage was found on the north slopeof the mountains about 37 nm northwest of the airport at the 3,000-foot level.The flight path through the trees indicated a direction of flight of 155° to160° and a 15° to 25° noseup attitude.
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The CVR revealed that, following the problem connected with establishing radio contact with the Bali Approach Control, the crew identified being overhead the airport by the swing of one of the two ADF's that were tuned to the NDB on the airport. The comment that "one's swinging, the other decided to wait," followed by the overhead report and the commencement of the approach descent, indicates the crew's actions.
The descent flight path derived by a computer generated plot was in error, because in making up the cards for the computer, someone, the keypunch operator or someone, entered an extra digit in one card and this cancelled several heading changes. This error was not noticed until much later; however, this mistake would only move the start of the descent a mile or so to the west and the descent would still have been made behind the mountains.
It is interesting to note that the VOR referred to by the crew is about 6 nm south, or beyond the airport from the direction PA812 was approaching. The VOR was operating but it was not being used by the crew of PA812.
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Last edited by ampan; 4th Jul 2017 at 00:27.