The ATSB was pushing back on opinions issued by an international group of aviation experts earlier in May that MH370 was deliberately crashed by the plane's pilot into the Indian Ocean.
During a Tuesday parliamentary hearing in Canberra, Australia, ATSB Chief Technical Officer Peter Foley, who led the organization's search for the missing plane, said, "I can say with great confidence that we considered every piece of evidence that we had at the time in an unbiased fashion."
"We have quite a bit of data to tell us that the aircraft, if it was being controlled at the end, it wasn't very successfully being controlled," Foley said.
"There's no earthly reason why someone in control of an aircraft would exhaust its fuel and then attempt to glide it when they have the option of ditching. The aircraft was probably descending in an uncontrolled manner," Foley added.
According to Foley, a key piece indication that the crash was an accident is the right outboard flap of the plane, which found off the coast of Tanzania in July 2015. The flap was recovered in a retracted position, which suggests that the plane was not configured for landing when it crashed. In addition, Foley denied claims that the pilot depressurized the cabin so that the passengers and crew members would pass out. That that would have required the 53-year-old pilot, Zaharie Ahmad Shah, to himself successfully battle the effects of depressurization for an hour, which is unlikely, Foley claims.
After scouring some 8,200 square kilometers of the search region in the southern Indian Ocean since the plane's mysterious disappearance, no concrete clues about the ill-fated flight's whereabouts have yet been found by the Texas-based Ocean Infinity company, which contracted with the Malaysian government to search for the wreckage on a "no find, no fee" basis in January.
So far, the only evidence of the Boeing 777 airliner is debris collected from Indian Ocean islands and on the east coast of Africa. At least three plane parts found have been confirmed as coming from the missing plane.
The lack of much evidence at all hasn't stopped a torrent of speculation about the causes of the plane's disappearance or what was going through its pilots' heads on that fateful day. On a episode of "60 Minutes Australia" last week, a panel of aviation experts accused Shah of purposefully killing the 239 people aboard as well as himself.
"[Shah] was killing himself; unfortunately, he was killing everybody else on board, but he did it deliberately," senior investigator with the Transportation Safety Board of Canada Larry Vance said on the Sunday night program.
Vance suggested Shah put on an oxygen mask before depressurizing the plane so that the passengers and crew members would pass out.
"There is no reason to believe that the pilot did not depressurize the cabin to incapacitate the passengers," Vance said.
Other members of the panel noted that the plane's path down the coast of Thailand and Malaysia would have made it difficult to track, as it moved in and out of the countries' airspace. The pilot did this deliberately, they said, to successfully hide his intentions and prevent military aircraft from intercepting him.
In 2016, Australian Prime Minister Malcolm Turnbull similarly speculated that it was "very likely that the captain planned this shocking event."
Ocean Infinity started a new search for MH370 January 22. The company allotted 90 search days to look for the plane, which have been scattered over several months due to bad weather. The search is expected to end mid-June.