The "final report" into missing Malaysia Airlines Flight 370 confirms the theory that someone deliberately diverted the plane from its course before it mysteriously vanished.
It recounts a series of mistakes that delayed the search and rescue operation — and one crucial failure of a system that could have immediately located the lost MH370.
The aircraft was fitted with four Emergency Locator Transmitters, in accordance with regulation, but every one of them failed, the independent report states.
Their batteries were within their expiry dates but no search and rescue agencies or other planes in the area reported receiving a distress signal.
"There have been reported difficulties with the transmission of ELT signals if an aircraft enters the water," reads the report released on Monday. "The ELT does not activate, or the transmission is ineffective as a result of being submerged under water."
It also notes that ELTs often break, citing a review of 173 accidents involving planes fitted with the transmitters, which showed they only activated in 39 cases.
"The ELT itself could be damaged or, very commonly in the case of fixed ELTs, the antenna or antenna cables become disconnected or broken," reads the report. "This significantly hampers any search and rescue effort and may mean the aircraft location remains undetected for a considerable time."
Grace Subathirai Nathan, whose mother Anne Daisy was a passenger on the lost plane, criticised the investigation as too limited and too unquestioningly reliant on findings by other parties.
"There is no explanation why none of the FOUR transmitters on the plane sent any distress signal," the Malaysian lawyer wrote on Facebook. "But apparently these transmitters, which are on every single plane, only work 22 per cent of the time."
Ms Subathirai Nathan said there had been some "mind boggling" failures by Malaysia's air traffic control, as well as one failure to follow procedure by Vietnam's air traffic control.
She said investigators had not checked passengers' phone numbers to see if they connected to cell towers — as the copilot's had in Penang, Malaysia — and were not even aware "that there are currently a few pieces of debris languishing in Madagascar for over 8 months."
She also questioned why only two phone calls, five hours apart, were made to the jet from the ground as it cruised off course for seven hours.
"Four years on we are none the wiser," she said. "The search must go on."
MH370 disappeared on March 8, 2014, when it veered off course en route from Kuala Lumpur to Beijing with 239 people on board, including six Australians.
The Boeing 777 vanished into thin air at the moment it switched from Malaysian airspace to that of Vietnam.
About 37 minutes after departure, Kuala Lumpur air traffic control cleared MH370 to switch to the communication radio frequency of the next control sector, where the pilot would be expected to report in.
It received the final communication from the doomed plane: "Good night Malaysia Three Seven Zero."
But it took some time before the controller in the receiving sector noticed that an expected aeroplane had not checked in, or shown up on his radar screen.
The report found that air traffic control failed to monitor radar continuously, relying too much on information from Malaysia Airlines, and failed to swiftly initiate an emergency response or contact the military for help.
Seven and a half hours after takeoff, the plane sent out an automated satellite communication from a position far southwest of its course. Then it vanished entirely.
Chief investigator Dr Kok Soo Chon told reporters in Kuala Lumpur yesterday that teams from eight countries had "finally reached a consensus."
He said there was no evidence of a malfunction with the aircraft that could have contributed to its disappearance. "It is more likely that such manoeuvres are due to the systems being manipulated," the report said.
The plane's change in direction over the Indian Ocean was made under manual control, which "points irresistibly to unlawful interference".
Investigators could not confirm that the plane was flown by anyone other than the pilot but also could not exclude the possibility of "unlawful interference by a third party," Dr Kok said. "We are not ruling out any possibility," he said. "(But) we are not of the opinion it could be an event committed by the pilot."
Theories have abounded over the downing of MH370. Many have speculated that it vanished in an act of murder-suicide by the pilot, suggesting motives including a troubled marriage or political protest. The explanation, backed by a 60 Minutes episode broadcast in May, was attacked by author Christine Negroni and other aviation experts as "absurd".
Others have pointed the finger at potential rogue passengers.
Dr Kok said there was no evidence of abnormal behaviour or stress in the two pilots that could lead them to hijack the plane — but the passengers were also cleared by police and had no pilot training.
He noted that no group claimed to have taken over the plane and no ransom demands had been made.
A previously unknown group called the Chinese Martyrs' Brigade did claim responsibility for MH370's disappearance days after it vanished, but officials believe it was a hoax. An email sent to journalists across China read: "You kill one of our clan, we will kill 100 of you as pay back."
But the message provided no details of what brought the flight down.
FAMILIES LEFT FRUSTRATED
Sakinab Shah, the sister of the MH370 pilot Zaharie Shah, said she was "relieved and happy" the report did not support the theory her brother was responsible for the plane's disappearance.
His co-pilot was Fariq Abdul Hamid, 27, who had been a pilot with Malaysia Airlines for seven years and was just finishing his mandatory training to transition to the Boeing 777.
Investigators also could not rule out the "possibility of intervention by a third party" when it came to their examination of the flight's cargo — 4566kg of mangosteen fruit and 221kg of lithium-ion batteries.
Mr Chon said the cause of the disappearance could not be determined until the wreckage and the plane's black boxes were found.
While the findings were initially called a "final report", the authorities later backtracked on this. The last line reads: "In conclusion, the team is unable to determine the real cause for the disappearance of MH370."
Relatives of the victims were given hard copies of the report and briefed by four members of the investigation team. But the family members said the meeting descended into a "shouting match" with officials as their frustration boiled over and "unsatisfactory responses left many angry".
Many were left sobbing and distraught, saying the report offered them "no closure" or claiming it contained inaccurate information. Two relatives of Chinese passengers said their loved ones were still alive, and Malaysian officials were hiding information as part of a "political conspiracy".
Danica Weeks, whose New Zealand husband Paul was on MH370, said the search had to go on, as it could affect the safety of future flights. "They need to keep searching — that's a given," said Weeks, from Perth.
"I understand that without new information, you're throwing the dice and hoping it's there.
"It's a matter of elimination. It's got to be somewhere. They can't just push it under the carpet and say 'that's it.'"
Jennifer Chong, from Victoria, whose husband Chong Ling Tan was on the flight, said that after 1605 days of waiting, the inconclusive report was "unacceptable".
THE MYSTERY OF MH370
The latest, privately funded search for the plane's wreckage was called off in May this year with no significant new findings. The operation, led by US-based firm Ocean Infinity, covered 112,000sq km in the southern Indian Ocean over three months.
It followed a $200 million search across an area of 120,000sq km by the Australian Transport Safety Bureau, in conjunction with Malaysia and China, which delivered its report last year.
Dozens of pieces of debris have washed up on Africa's east coast, suggesting the Boeing 777 went down somewhere in the Indian Ocean. Three have been confirmed as belonging to MH370, with a fragment of the plane's wing found washed up on Reunion Island, thousands of kilometres from Kuala Lumpur.
Experts mapped the Boeing 777's course over Malaysia and the Indian Ocean by looking through hourly data hook-ups with a satellite.
There was nothing to suggest the plane was evading radar, or evidence of behavioural changes in the crew, the report said.
There did not appear to have been problems with fuel and the aircraft's power system, including autopilot function, appeared to have been working throughout the flight. There was no evidence the jet had been remotely controlled.
Malaysia's government says it is open to resuming the search if credible evidence of the plane's location emerges. The nation's transport Minister Anthony Loke said the government would take action over any misconduct indicated by the report findings.
But despite the efforts of 26 countries, the missing plane has not been located, more than four years after it vanished.
The fate of MH370 remains one of the world's greatest aviation mysteries.
— With wires