Gemma Holliani Cahya in Jakarta, and Associated Press – A malfunctioning automatic throttle may have caused the pilots of a Sriwijaya Air jet to lose control, leading to the Boeing 737-500's plunge into the Java Sea last month, Indonesian investigators have said.
National transportation safety committee investigators said on Wednesday they were still struggling to understand why the jet nosedived into the water minutes after taking off from Jakarta on 9 January, killing all 62 people on board.
The investigators issued a preliminary report that provided new details of the pilots' struggle to fly the plane almost as soon as it became airborne.
The lead investigator, Nurcahyo Utomo, said the left engine's throttle lever moved backwards on its own while autopilot was engaged, reducing the power output of that engine before the jet plunged into the sea.
He said pilots of previous flights had reported problems with the automatic throttle system on the 26-year-old jet.
The pilots' last conversation with air traffic control was about four minutes after takeoff, when the crew responded to an instruction to go up to 13,000 feet (4km). The plane's flight-data recorder showed the plane reached an altitude of 10,900 feet (3.3km) and then began declining, Utomo said.
While on autopilot, power to the left engine was reduced, while the right engine's power remained steady. The pilot fought to bring the plane up, but it rolled on to its left side, Utomo said. A minute later the data recorder showed the automatic throttle had been disengaged as the plane pitched down. The flight-data recorder stopped recording a few seconds later.
Divers were able to recover the crashed plane's flight-data recorder, which tracks hundreds of parameters showing how the plane was being operated, but were unable to find the memory unit from the cockpit voice recorder, which could tell investigators what the pilots were doing – or failing to do – to regain control of the plane during the brief, erratic flight. The module apparently broke away from other parts of the voice recorder during the crash.
Investigators are working with Boeing and the engine-maker, General Electric, to review the information from the flight-data recorder. A team from the US National Transportation Safety Board and the Federal Aviation Administration has also joined the investigation.
The plane had been out of service for almost nine months last year because of flight cuts caused by the coronavirus pandemic. Regulators and the airline said it underwent inspections before resuming commercial flights in December.
Martasari Mahulette, who lost her husband Ricko Mahulette in the plane crash, said she still cannot find the answers of what happened to the plane. "I have the right to know the truth. The plane dove into the sea. There must be something wrong with it. I need to know what happened to the plane," she said.
"I think I'm like everybody else. We just want our loved ones to return, to arrive safely ... But I have found strength in God to accept this."
Regulations stipulate Sriwijaya Air is obliged to pay compensation to the families of victims of the crash worth Rp 1.25bn ($89,000) per passenger.
Slamet Bowo Santoso, another victims' family, said Sriwijaya Air asked them to sign a document that said they will not sue Boeing if they receive compensation from the airline. "That's why we decided to not sign it. I don't want to sign it and then we suddenly act like this tragedy has ended just like that," Bowo said.
Bowo said that with the help of Nolan Law Group, a Chicago-based law firm, his family was going to file a lawsuit against Boeing.
Bowo lost four family members in the plane crash. Bowo's older brother Mulyadi Tamsir, 40, was on the flight, along with his wife, Makrufatul Yeti Sriyaningsih, who was two weeks pregnant and Makrufatul's mother and sister.
"Whatever the result will be, it will not bring them back but at least it could help us understand what happened and heal our wounds," Bowo said.
She and their only child, a 6 years old child, have left their house in Pontianak, West Kalimantan, and are now staying in Makassar, South Sulawesi, her husband's hometown. They are staying temporarily in her in-law's house to gather and pray with his late husband's family until the 100th day.
Mahulette said that yesterday the National Transportation Safety Commission (KNKT) held a meeting for the victims' families in Jakarta on Feb. 9, exactly a month after the plane crashed, to share the preliminary report of the plane investigation to the families.
"My husband's brother joined the meeting yesterday," she told the Guardian over a phone call on Wednesday.
Although she appreciated the KNKT, government, search and rescue team and everyone who has done their best to investigate the crash, she [missing text].
However, Mahulette said she heard that other families were asked by Sriwijaya Air to sign release and discharge documents if they wanted to receive compensation. Mahulette said she is planning to go to Jakarta in a few weeks to meet with the airline company.
"I just want to say to them, please give us our rights in accordance with the law without any additional requirements. They can't make such requirements. Don't make it even more difficult for us. I hope that the government can help us oversee this compensation process," she said.
"I have the right to know the truth. The plane dove into the sea. There must be something wrong with it. I need to know what happened to the plane," she added.
Meanwhile, Slamet Bowo Santoso, another victims' family said that Sriwijaya Air asked them to sign a document that said they will not sue Boeing if they receive compensation from the airline.
"That's why we decided to not sign it. I don't want to sign it and then we suddenly act like this tragedy has ended just like that," Bowo said, "we also have agreed to sue Boeing."
Bowo said with the help of Nolan Law Group, a Chicago-based law firm, his family is going to file a lawsuit against Boeing.
Bowo lost four family members in the plane crash. Bowo's older brother Mulyadi Tamsir, 40, was on the flight, along with his wife, Makrufatul Yeti Sriyaningsih, who was two weeks pregnant and Makrufatul's mother and sister.
"Whatever the result will be it will not bring them back but at least it could help us understand what happened and heal our wounds," Bowo said.
It's been a month since Bowo lost his bright brother. Mulyadi was the chairman of the Association of Islamic Students (HMI) in Indonesia from 2015 until 2018, but had since become a politician from the People's Conscience party.
He was the pride of his family. While the rest of his family, including Bowo, live in a small village in Sintang Regency, West Kalimantan. Mulyadi is the only one that survived in Jakarta and built his career there.
"My brother was the brightest and most successful one in the family and the only one who can survive Jakarta. We put our hope so much from him; that one day our children can also get better education and better life in the capital," Bowo said, "this is a big loss for us all."
The disaster has reignited concerns about safety in Indonesia's aviation industry, which grew quickly after the economy was opened after the fall of the Indonesian dictator Suharto in the late 1990s. The US banned Indonesian carriers from operating in the country in 2007, lifting the action in 2016, citing improvements in compliance with international aviation standards. The EU lifted a similar ban in 2018.
Sriwijaya Air has had only minor safety incidents in the past, though a farmer was killed in 2008 when a plane went off the runway while landing due to a problem with hydraulics.
In 2018, a Boeing 737 Max 8 jet operated by Indonesia's Lion Air crashed, killing 189 people. An automated flight-control system played a role in that crash, but the Sriwijaya Air jet did not have that system on board.