TNAG-2856-FCO40-4109-Hong-Kong-compensation-claim-regarding-Korean-Air-Lines-Flig-1993 — Page 108

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been released in 1985, was also obtained. The copy tape which did not contain silent periods and covered the time period from 17:07:40 to 18:35:40 hours, appeared to contain a mixture of channels 3 and 4.

1.15.2.6

The period between 18:59:09 and about 19:11:30 hours, in which all channels including the time signal channel were silent, was examined. The length of tape for this time period corresponded to about three minutes recording at normal speed. The recorder may have been stopped about thirty- two minutes after the last communications from KE 007 and rewound for checking. It had then been wound forward past the end of the recordings on the tape and restarted about twelve minutes later. This was normal procedure in circumstances involving search and rescue and aircraft accidents.

1.15.2.7

Regarding the period between 18:35:25 and 18:40:10 hours, in which all channels including the time signal channel were silent, the representatives of Japan provided the following additional explanation on 21 May 1993:

1.15.3

"... the silent periods (between 18:35:25 and 18:35:40 hours, and between 18:39:41 and 18:40:10 hours, were] caused by the change of the operating mode from 'work' to 'guard'. During these periods the channel 4 contained the recordings corresponding to the time period of the clock signal channel. All channels including the clock signal channel were silent in the period between 18:35:40 and 18:39:41.

The duration of the silent period of all channels was 4 minutes and 1 second and the length of tape for this time period corresponded to 3 minutes and 34 seconds.

From these points, it is considered that the recorder may have been stopped about 8 minutes after the last unrecognizable communication from KE 007 and rewound for checking. It had then been wound forward past the end of the recordings on the tape and restarted about four minutes later. This was normal procedure for the aeronautical ground station operator in circumstances involving message which was difficult to recognize and further attempt to clarify with the aircraft involved had failed."

USSR Air Defence command centre recordings

1.15.3.1 The representatives of the Russian Federation made available two original tapes and transcripts containing air-ground communications between the USSR interceptor aircraft and their command centres, and ground-ground communications between the USSR Air Defence command centres. The audio quality on the two USSR command centre tapes was good and contained a Morse code time signal. These tapes matched the air to ground communications by the USSR interceptor pilots as monitored by Japanese and United States sources in 1983.

1.15.4

1.15.4.1

Time correlation of CVR, DFDR and radio communications

The CVR was time correlated to Tokyo time based on thirty-seven radio transmissions to or from Tokyo Radio between 18:08:57 and 18:27:21 hours. The CVR contained ten radio. transmissions between KE 015 and Tokyo Radio from 18:08:57 to 18:14:15, seven radio transmissions between KE 007 and Tokyo Radio from 18:14:59 to 18:15:21, two radio transmissions between KE 015 and Tokyo Radio from 18:17:44 to 18:17:49, seven radio transmissions between KE 007 and Tokyo Radio from 18:20:02 to 18:23:00, five radio transmissions between Dynasty 312 and Tokyo Radio from