(Bloomberg) -- Indonesian investigators were closing in on the flight recorders from a Boeing Co. passenger jet that crashed on Saturday and confirmed the plane was intact when it struck the Java Sea, reducing the likelihood of a terror attack.
As the recovery mission enters its third day, search teams have identified the site where the Sriwijaya Air jet carrying 62 people went down, plunging more than 10,000 feet shortly after takeoff. Some wreckage from the Boeing 737-500 has been pulled up and possibly the so-called black boxes located. The plane was intact when it struck the sea, National Transportation Safety Committee Chairman Soerjanto Tjahjono said in a text message.
Search crews have detected the sound signature of so-called pingers used to help locate the crash-proof flight recorders, according to officials. The plane’s black boxes -- one capturing sound in the cockpit and another monitoring the plane’s track and other flight data -- are equipped with underwater locator beacons that broadcast a unique sound when they come in contact with water to help investigators pinpoint their location in wreckage.
Indonesia, one of the world’s fastest-growing aviation markets prior to the coronavirus pandemic, also has one of the worst safety records. The archipelago of more than 17,000 islands has suffered 104 accidents and 2,353 related fatalities, data from Aviation Safety Network show. Its planes were barred by the European Union in 2007 over safety concerns and the full ban wasn’t lifted until 2018.
Jet Crash Adds to Long List of Aviation Disasters in Indonesia
Weather has been a contributing factor in several of the past crashes in Indonesia and may have played a part in this accident. On Saturday, heavy rain in Jakarta, which is still in Monsoon season, delayed the takeoff for the 90-minute SJ182 flight to Pontianak on the island of Borneo. The airport’s official weather report about 10 minutes before the crash said there was light rain with a cloud ceiling starting at 1,800 feet above the ground.
Four minutes after takeoff, controllers noticed the aircraft was not on its assigned track. It radioed the crew, and within seconds, the aircraft disappeared from radar. Flightradar24’s tracking data showed the plane leveling off at an altitude of about 10,000 to 11,000, before a rapid descent to the water in just 14 seconds. That meant it was dropping at more than 40,000 feet per minute.
The flight track also suggests the jet was intact as it dove toward the water, said John Cox, president of Safety Operating Systems and a former airline pilot who flew 737s. The plane was transmitting its position down to the water, which means its electrical system appeared to be functioning through the flight, he said.
One of the most common causes for planes to fall from the sky – so-called aerodynamic stalls in which the wings lose lift – appears not to have occurred, he said. Accidents involving stalls, such as the plunge of Air France Flight 447 in the Atlantic Ocean in 2009, have gone down more slowly.
“Based on what we know so far, it is very difficult to get the airplane to come down that fast,” Cox said, referring to the Sriwijaya Air crash. “If the data is accurate, it is going to be a pretty extreme event.”
The plane that crashed on Saturday is a decades-old Boeing 737 model, not the newer 737 Max just emerging from a worldwide grounding. The 737-500 model used in Flight SJ182 is among the safest planes currently flown, according to data from Boeing. The first crash of a 737 Max also occurred in Indonesia when Lion Air Flight 610 went down in 2018, killing 189 people.
“This is not even the model before the Max, it has been in service for 30 years so it’s unlikely to be a design fault,” said Richard Aboulafia, an aviation analyst at Teal Group Corp. “Thousands of these planes have been built and production ended over 20 years ago, so something would have been discovered by now.”
Sriwijaya Air, which was established in 2003 and now flies 53 routes, most of them domestic but some international including to Penang, Malaysia and Dili, Timor Leste, hasn’t had any fatal accidents previously. There have been four other incidents involving its jets, the last in May 2017, when a Boeing 737-33A overshot a runway.
Preliminary readings from flight data transmitted by the aircraft via the Automatic Dependent Surveillance–Broadcast system appeared to show “possible disorientation” by the pilots, said aviation analyst Gerry Soejatman.
“We have to wait for the final report of the investigation to know the true cause of the incident, but the preliminary data appears pointing to possible disorientation in the cockpit, to which the bad weather is a factor here,” he said.
Still, finding the black boxes may not be easy. In a number of high-velocity crashes, such as what apparently occurred with the Sriwijaya Air flight, the pingers have broken loose from the recorders, complicating the searches.
Without access yet to the plane’s black-box flight recorders, it’s impossible to say what may have triggered the sudden dive, said Jeffrey Guzzetti, the former head of accident investigations at the U.S. Federal Aviation Administration. Flight-crew confusion, instrumentation problems, catastrophic mechanical failures or even an intentional act were among the possible scenarios, he said.
Boeing is “closely monitoring the situation,” spokeswoman Zoe Leong said in a statement. “We are working to gather more information.” Sriwijaya Air said it will work with relevant authorities in evacuation and investigation efforts.
Of the 62 people on the flight, 50 were passengers, including seven children and three infants, and there were two pilots, four cabin crew and six off-duty staff, local media reported. There were no foreign nationals on board.
Read more: Why Indonesia Remains One of the World’s Worst Places to Fly
The crash comes as the aviation industry reels from the effects of the coronavirus pandemic, which brought air travel to its knees. Covid-19 left many carriers in distress, along with a constellation of aerospace manufacturers, airports and leasing firms. With many planes still grounded, pilots aren’t getting enough opportunities to fly.
On Sept. 15, an Indonesian flight carrying 307 passengers and 11 crew to the northern city of Medan momentarily veered off the runway after landing, sparking an investigation by the transport safety regulator. It found the pilot had flown less than three hours in the previous 90 days. The first officer hadn’t flown at all since Feb. 1.
“This concern about lack of flying hours among pilots might have materialized here,” Soejatman said. “The Indonesian airlines domestic market is rebounding from the Covid hiatus and this might have put significant strain on the crew. Compound that with all the personal conditions that these people might have from the reduced pay and everything, this is a challenging time for the industry.”