Indonesia rescue workers are searching for the black box that was on board a Russian passenger jet that crashed in West Java last week.
The Sukhoi Superjet 100 was on a six-nation sales tour when it cashed during the Indonesian flight.
At least 45 people were on board.
Rescue workers believe the information in the flight-recorder could shed light on its crash, into a volcano.
A West Java military commander said the mission has proven difficult due to the rough terrain of the area.
Eighty Russian rescue workers and forensic experts have arrived in Indonesia to help in the recovery efforts.
Rescuers found some communication gear from the plane, but have not yet recovered the flight-recorder.
The crash deals a blow to Sukhoi's marketing plans for the Superjet 100. A local Indonesian airline has put its order for 12 of the jets on hold, pending the air crash investigation.
Sarah Sheffer, Reuters