Officials load wreckage from the crashed Lion Air plane for investigation at Tanjung Priok Port in Jakarta, Indonesia, Nov. 5, 2018. (Xinhua/Zulkarnain)

JAKARTA, Nov. 5 (Xinhua) -- The Indonesian transport safety committee unveiled on Monday that the airspeed indicator from the Lion Air plane that crashed into the waters off West Java province a week ago suffered from malfunction and search for the cockpit voice recorder (CVR) is hampered by the thick layer of mud and sand at the sea floor.

The glitch was found after the committee downloaded the data from the flight data recorder (FDR) which has been retrieved from the sea bed, investigator at the committee Captain Nurcahyo Utomo said.

The airspeed indicator of the almost new Boeing 737 Max 8 jet plane had suffered from malfunction during the last four flights, according to the investigator.

But the committee could not determine that the malfunction of the device was the cause of the tragedy, said Nurcahyo.

"We will probe further what was the cause of the malfunction, how the repair was undertaken, how the pilot flied this aircraft with such malfunction," he said.

Meanwhile, the search operation to retrieve CVR was hampered by a thick layer of mud and sand at the sea floor where the device was suspected, said Muhammad Syaugi, head of the national search and rescue agency.

Despite the weak signals released by the ping locator installed on the CVR were detected, the divers still could not find it.

"Until tonight (Monday night), we could not find it, One of the major obstacles is the layer of mud and sand at the sea floor that is more than one meter thick. This is the problem for the divers to find the CVR," he said.