BANGKOK — A preliminary investigation into the crash in Indonesia final month of Sriwijaya Air Flight 182 has discovered that a distinction within the degree of thrust between the aircraft’s two engines might have contributed to the plane rolling over earlier than it plunged into the Java Sea, investigators mentioned Wednesday.
As in most crashes, the investigators are a variety of things which will have contributed to the trigger. They’re assessing data from the flight information recorder and the aircraft’s upkeep information, however searchers haven’t recovered the cockpit voice recorder, which might inform them what the pilots had been saying of their remaining minutes.
A distinction within the degree of thrust — the drive of the engines that propels the plane ahead — could make planes tough to manage. It isn’t clear, at this level, why that drawback might have occurred throughout the Sriwijaya flight.
Many questions stay unanswered, together with why the pilot and co-pilot had been unable to get well management of the aircraft earlier than it plummeted greater than 10,000 ft in lower than a minute, mentioned Nurcahyo Utomo, chief of the investigation group.
“What occurred? We don’t know,” he mentioned after the 31-page preliminary accident report was launched by Indonesia’s Nationwide Transportation Security Committee. “What are the issues? We can’t reply that but. We nonetheless can’t clarify if there was an auto-throttle malfunction.”
The Boeing 737-500 crashed minutes after taking off on Jan. 9 from Soekarno-Hatta Worldwide Airport in Jakarta, the Indonesian capital. The crash killed all 62 folks aboard, together with six energetic crew members.
One focus of the investigation has been the auto-throttle, which is a system that controls the thrust of a aircraft’s engines and is separate from the autopilot operate. Within the occasion of an auto-throttle malfunction, it’s typical for a pilot or co-pilot to easily flip the system off. The auto-throttle makes use of information entered by the pilot to mechanically regulate the 2 levers within the cockpit that management the thrust of the engines.
The auto-throttle system on the Sriwijaya plane had malfunctioned twice within the weeks earlier than the crash and had been fastened after each incidents, the aircraft’s restore information present.
Flight information point out that when the plane reached an altitude of eight,150 ft throughout the deadly flight, the thrust lever for the left engine was lowered whereas the correct engine’s thrust lever remained unchanged. At 10,600 ft, the differential between the thrust of the 2 engines might have prompted the aircraft to start out rolling to the left, the report mentioned.
Regardless of the issues with the aircraft’s auto-throttle on earlier flights, Mr. Nurcahyo mentioned there was no clear proof that it malfunctioned on this flight. As well as, there are numerous airline methods that may have an effect on the engines’ thrust.
The auto-throttle itself receives enter from 13 plane parts, he added, any of which might have contributed to the issue.
“So why the anomaly occurred within the throttle, which parts prompted it, we nonetheless can’t decide,” he mentioned.
Prita Widjaja, a senior investigator with the transportation committee, mentioned one key query that remained was how far the lever for the left engine moved and the way a lot the plane’s energy was lowered.
Indonesian investigators had been required by worldwide conference to launch a preliminary report 30 days after the air catastrophe.
Due to the coronavirus pandemic, the 26-year-old plane had not been flown for 9 months earlier than going again into service in December. It then flew 132 flights within the weeks main as much as the crash. Investigators didn’t cite any proof that the hiatus contributed to the catastrophe.
Three days after the crash, divers recovered the airplane’s flight information recorder, one of many so-called black packing containers, which information details about the jet’s mechanical operation. It has supplied key proof within the investigation.
However the inquiry has been hindered by the lack of searchers to find the essential reminiscence module of the opposite black field, often known as the cockpit voice recorder. That system information sounds within the cockpit, equivalent to engine noises and conversations between the pilot and co-pilot.
Divers retrieved many of the cockpit voice recorder, however the reminiscence unit broke unfastened from the casing and searchers concern it’s buried in a layer of seafloor mud that’s two to a few ft thick. They’re nonetheless looking for the module in waters about 60 ft deep, however the effort has been hampered by tough climate and poor visibility.
The comparatively small measurement of the aircraft’s particles discipline — about 260 ft by 360 ft — signifies that the aircraft was intact when it hit the water and broke up on affect, not within the air.
The Sriwijaya plane was the third to crash into the Java Sea in simply over six years after departing from airports on Java, one in all Indonesia’s 5 important islands.
In December 2014, Air Asia Flight 8501 crashed into the Java Sea off the coast of Borneo with 162 folks aboard because it flew from the Indonesian metropolis of Surabaya to Singapore. Investigators ultimately attributed the catastrophe to the failure of a key element on the Airbus A320-200 and an improper response by the flight crew.
And in October 2018, Lion Air Flight 610 nose-dived into the Java Sea northeast of Jakarta minutes after taking off for Pangkal Pinang with 189 aboard. Investigators concluded that the anti-stall system malfunctioned on the Boeing 737 Max, a more recent mannequin than the Boeing that crashed final month.
A regulation agency in Illinois filed go well with towards Boeing final month on behalf of an Indonesian household that misplaced three kinfolk within the Sriwijaya crash. The go well with claims that elements of the plane malfunctioned throughout the temporary flight, probably together with the auto-throttle, inflicting the crash.