Russian investigators have discovered that the cockpit-voice recorder from the crashed Itek Air Boeing 737-200 contains no trace of the ill-fated jet's final flight.
The 737 came down outside of the Kyrgyz capital Bishkek shortly after departing the city for Tehran on 24 August.
Russia's Interstate Aviation Committee (MAK), assisted by the US National Transportation Safety Board, has completed an initial reading of the data from the aircraft's two recorders.
But MAK says preliminary information shows the cockpit-voice recorder only contains a record of a previous flight on the Moscow-Bishkek sector.
"The record of the flight with the emergency is absent," it states.
MAK adds that the quality of the flight-data recorder information is "unsatisfactory" because of partial thermal damage to its magnetic tape, caused by the intense fire which followed the crash.
The available data will be synchronised with radar-track information and recordings from the air traffic control service.
"Restoration of the information will take a long time," says MAK. Sixty-five of the 90 passengers and crew members on board the aircraft were killed in the accident.
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