Indonesian authorities say attempts to retrieve crucial black boxes from a crashed Sriwijaya Air jet have been hampered by wreckage strewn across the seafloor.
Indonesian National Transport Safety Committee chief Soerjanto Tjahjono had initially hoped the recorders could be retrieved Monday after searchers detected signals broadcast by the safety devices.
However, divers by Monday night had still to retrieve the bright orange recorders, thought to be within 150m to 200m of wreckage.
The flight data and cockpit voice recorders will be critical in determining what caused the Boeing 737-500 jet with 62 people on board to plummet 10,000 ft in less than a minute and smash into the sea minutes after take-off from Jakarta.
Officials believe the plane was still intact when it hit the sea on January 9 because of the spread of the wreckage and the fact the aircraft was transmitting information as it plummeted.
Flight SJ182 was not on its assigned heading but the pilots did not respond to queries from air traffic control about the change. Why this was so will be among the questions investigators will be hoping information on the black boxes will answer.
The aging Boeing 737 was about 11 nautical miles north of Jakarta’s Soekarno International Airport on a flight between Jakarta and Pontianak in Borneo when contact was lost.
Searchers have retrieved body parts and wreckage, including part of an engine, some of which have already been taken to Jakarta.
Flight tracking and specialist air crash sites have already revealed some information about the flight.
The Aviation Herald reported the aircraft had departed Soekarno International Airport at 2:36 pm local time, climbed through 1700 feet and was cleared to 29,000 feet.
“Departure control subsequently noticed that the aircraft was not on its assigned heading of 075 degrees, but tracking northwesterly and queried the crew about the heading at 14:40L, but received no reply, within second(s) the aircraft disappeared from radar,” it said.
Flightradar24 ADS-B data showed the 737 departed on runway 25R and was climbing through 10,600 feet at 2:39:50 pm local time about 11nm north of Soekarno airport then lost 10,000ft of altitude in less than a minute.
Three fishermen from nearby Lancang Island told CNN they had heard an explosion and experienced a sudden large wave about the time the plane is thought to have crashed in dark and rainy conditions.
They smelled fuel and spotted debris, one of them said.
“I heard very loud explosion. I thought it was a bomb or a big thunder. We then saw the big wave, about 2 meters high, hitting our boat,” Hendrik Mulyadi told the network.
Hendrik’s colleague, Solihin, described the sound as “a bomb on the water.”
The aircraft was carrying 50 passengers, including seven children and three babies, and 12 crew members. All were Indonesian.
Media reports said the captain, Afwan, was a former air force veteran who had decades of flying experience, His first officer had also accrued more than 5000 hours on a Boeing 737 over seven years.
One passenger is said to have missed the flight because his COVID PCR test results had not arrived prior to departure.
The crash aircraft is more than 26 years old but airline officials said it was in good condition.
It is a much older plane than the 737 MAX and pre-dates a controversial flight software system linked to two fatal MAX crashes.
The crash has prompted renewed speculation about Indonesia’s chequered safety record and comes after the 2018 crash of Lion Air B737 MAX with 189 onboard and a 2014 disaster involving an AirAsia Airbus A320 carrying 162 passengers and crew.
Indonesian airlines were at one stage blacklisted by the European Union because of worries about safety oversight but all carriers from the populous South-East Asian nation were removed from the list in 2018 after it passed an International Civil Aviation Organization country audit.
Nonetheless, questions have persisted about pilot training and maintenance at some carriers.