The black box has been found for the Lion Air flight which crashed soon after take off from Jakarta on Monday.
The Boeing 737 carrying 189 people plummeted into the Java Sea.
No survivors have been found.
The pilot had asked for permission to turn back to the airport but then contact was lost.
Reports say the aircraft had experienced technical problems on its previous flight.
The plane was due to fly one hour to the western city of Pangkal Pinang.
The search continues for the second black box which would hold recording of the conversations between the pilots.
