The hunt for missing Malaysia Airlines flight MH370 took a new twist after satellites detected objects off the coast of Australia.
But what does that mean for the multitude of theories regarding the fate of the missing plane?
Experts now say that if the objects do turn out to be part of the jet that disappeared 13 days ago, then the most likely cause of a crash would have been a catastrophic malfunction.
Commercial pilot Robert Mark, who is editor of Aviation International News Safety magazine, said that because the plane deviated off-course in a straight line that it's most likely passengers on the plane were knocked unconscious by after the cabin depressurised or ran out of oxygen.
Mr Mark told The Daily Mail: "What I think is interesting is that if you look at where the plane was last seen on radar and where the debris has been found, it is almost a straight line.
"I would say it means that once the aircraft turned, it didn't change course. A mechanical fault or emergency seems more plausible to me."
Experts say that because the flight path would have taken the plane south, a hi-jacking was extremely unlikely.
- Objects 'could be a wing, tail'
- Erased data could hold key
- Search for MH370 continues
- Pilots 'unconscious after take-off'
Mark told The Daily Mail that it was possible for the plane to fly four or five hours on auto-pilot before crashing into the ocean when it ran out of fuel.
The new evidence would also clear pilot Zaharie Ahmad Shah from accusations he may have been involved in a plot to steal the plane.
While Australian authorities have said the objects were a "credible lead", they were careful to say that there was no confirmation that this was the missing plane.
Families still hold hope
The father of a Chinese passenger on board Malaysia Airlines 370 clung to hope Thursday despite Australia's announcement satellites have spotted possible aircraft debris, insisting "My son is still alive".
Canberra said that two objects possibly related to the search had been located in the remote southern Indian Ocean.
But Wen Wancheng refused to accept the announcement meant he had lost his son, one of 153 Chinese passengers on the flight which disappeared on March 8 during a flight to Beijing.
"My son is still alive. My son is still alive," said the 63-year-old from Shandong province. "I don't believe the news."
"Do you think I would believe my son is gone?" he added. "Can I believe he is in the sea?"
Chinese citizens make up two-thirds of those on the MH370 manifest, and their anguished relatives have been waiting for news at the Lido Hotel in Beijing.
While some said there was "no new information" despite the Australian images, many appeared in more sombre mood than in previous days.
Several relatives linked arms as they walked past about 70 reporters outside their briefing room, looking downwards or covering their faces amid the sound of cameras.
Others marched quickly past the media crowd, appearing disorientated as they searched for the exit.
"I am sick of hearing there is new information only for it to be dismissed later," one man said angrily.
Another man, Zhao Chunzeng, who declined to identify his relative on board, said families were seeking a confirmed discovery.
"We are waiting, just waiting and we can't respond to news until it is definitely confirmed," Zhao told AFP.
Asked if he felt that the Australian announcement had greater significance as it came from Prime Minister Tony Abbott, he said: "Maybe, but we will still have to wait and see."
Inside the briefing room, relatives earlier had angrily confronted a Malaysia Airlines official over the lack of information on the flight's whereabouts.
"You are cheating us," one man said. "You are cheating us relatives. You have been torturing us. You are torturing our will."
Another relative mentioned the possibility of a hunger strike, which some family members have suggested in recent days as the anxious wait for news continues.
"We are here to learn the truth," the man said. "We can choose not to eat, we can choose not to sleep. We can choose to not receive your care.
"We want our relatives back. We don't want our relatives to be sacrificed to a political fight."
Chinese foreign ministry spokesman Hong Lei said the government was paying "great attention" to the news from Australia.
"The Chinese side is ready to make relevant arrangements based on the latest updates," he said in a statement without elaborating.
State broadcaster CCTV said in a posting on its verified account on Sina Weibo, a Chinese equivalent of Twitter, that the China Maritime Search and Rescue Centre would maintain its existing search plan, given the uncertainty over whether the debris was connected to the missing jet.
The nearest Chinese search vessel was two days away from the location of the sighting, it added.
An online chat group organised by some of the passengers' relatives through China's popular WeChat mobile app was a flurry of nervous activity as news of the Australian disclosure spread.
Some posted panicked reactions, while others urged calm and noted wearily that most of the "discoveries" announced over the past 13 days had turned out to be false leads.
At the Lido hotel, some relatives have posted messages on a large whiteboard near the room where airline officials have been holding daily briefings.
"Mum and Dad, please come home safe," read one message shown on Hong Kong-based Phoenix television. "Your son is waiting for you."
"Dear father, please come back safely," read another. "My heart aches not to have you by my side. I just want to see your face. I just want to hold your hand. I just want you to tell me what to do."