JAKARTA (Reuters) - Indonesia is still trying to find the cockpit voice recorder from a Lion Air jet that crashed into the sea near Jakarta last month, even though its “ping” signal is no longer being detected, a transport safety panel said on Thursday.

The nearly new Boeing Co. 737 MAX passenger plane crashed into the sea on Oct. 29, just minutes after taking off from Jakarta en route to an island off Sumatra, killing all 189 on board.

Authorities have downloaded data from one of the black boxes found days after the crash, the flight data recorder, but are still looking for the cockpit voice recorder.

“We’re still putting in all our efforts to find the CVR (cockpit voice recorder),” Soerjanto Tjahjono, the chief of Indonesia’s National Transport Safety Committee (KNKT), told parliament on Thursday.

The search team was targeting an area with a radius of 300 metres (984 ft) using sonar and dredging mud from the sea floor, even though a signal initially heard from the recorder was now not being detected, he said.

Efforts to find the second black box have been hampered by strong currents and complicated by the presence of energy pipelines in the area.

The cockpit voice recorder could hold vital clues to help answer questions over the role that a new emergency system on the 737 MAX, designed to prevent it from stalling, may have played in the crash.

After the crash, the U.S. Federal Aviation Administration warned airlines that erroneous inputs from the anti-stall system’s sensors could lead the jet to automatically pitch its nose down even when autopilot is turned off, making it difficult to control.

Boeing has already provided two updates for operators around the world that re-emphasize existing procedures to deal with situations relating to the system.

Lion Air, one of Boeing’s largest customers globally, said on Thursday it would meet the U.S. plane maker next week to review the airline’s orders for 261 Boeing 737 MAX series jets in the period until 2035.

KNKT is due to announce next Wednesday the preliminary results of its investigation into the crash.