One out of the two black boxes that belonged to the Sriwijaya Air plane that crashed in the Java Sea has been recovered by an Indonesian search team.

The plane which crashed shortly after take off three days ago had 62 people on board before the incident occurred, CNN reports.

Flight data recorders process a flight’s information, including pressure, airspeed and altitude. The second black box, the cockpit voice recorder, has not yet been found.

The box is a crucial instrument for investigators to probe the cause of the crash.

The flight data recorder was found as a team — including divers and a remotely operated underwater vehicle — swept the sea floor in search of the black boxes that were on flight SJ 182

Commander of the Indonesian National Armed Forces Marshal Hadi Tjahjanto said that the black boxes’ underwater acoustic beacons, which send out a series of pings to help searchers find them, had both been detached. He was optimistic, however, that the team would find the second black box soon.

Head of the National Transport Safety Committee, Soerjanto Tjahjono, said that authorities would need two to five days to read the recovered black box’s data.

He said, “We are expecting that through this investigation we can unfold the mystery of this accident.”