"We are still confident that we will find the aircraft between now and the completion of searching the search area of 120,000 square kilometres," he said. "The more we search, the more likely the aircraft is to be in the area we are still looking at. John and Kaylene Mann lost relatives on both Malaysia Airlines flights MH17 and MH370. Credit:Glenn Hunt "The only level of uncertainty is the behaviour of the aircraft at the very end of its flight. The weight of the evidence indicates that there were no control inputs to the aircraft at the end of its flight and that's the basis on which we have calculated the search area. "Occasionally I will lie awake at night thinking about whether we have got everything right. Normally at some point I will say to myself there's not much I can do about this at 3am in the morning. "We are not at the stage where we are throwing in the towel by any means. But governments have put a limit on the search they are willing for us to undertake."

Searching the entire area will cost $180 million, of which the Australian government has pledged $60 million. Mr Dolan acknowledged that some families who lost loved ones were contemplating the possibility that MH370 may not be found. Kaylene Mann, who lost her brother and sister-in-law, Rodney and Mary Burrows, said she had promised her elderly mother she would join a ship organised to take families for a wreath-laying service in the search area of the Indian Ocean if the wreckage wasn't found. Her husband, John Mann, lost two relatives on Malaysia Airlines flight MH17, which was shot down by a missile. "I am going to be really upset and I am sure everyone else will be if it finishes and nothing more is going to happen," Mrs Mann said. "But I don't see what else can be done. I really think it is there and they are doing everything in their power to find it.

"If possible I would like the aircraft recovered, but if it can't be I would be happy for it to be left there and to have a memorial service of some sort out there. Mum's made us promise that if there's anything like that we would be there." Michael Hyland, an aviation lawyer with Sydney firm LHD, representing some families who lost members on MH17, said it was now too late for relatives of people lost on MH370 to instruct lawyers, given the limitation period for commencing litigation expires on March 7, 2016. He said, in the absence of the aircraft's black boxes, unless lawyers for the plaintiffs obtain under court orders compelling evidentiary documentation implicating the airline, it would be difficult to establish liability. "They will face the burden of a permanent question in their own minds, asking what actually happened to their relative," he said. "Secondly, even though no amount of compensation can replace their lost family member, they will not have the opportunity to commence legal action against the airline once the limitation period has expired. "Statistically the chances are diminishing if they have covered 75 per cent of the territory."

In a statement the airline said: "Malaysia Airlines will not be discussing matters of compensation as it is strictly confidential. It would be inappropriate to comment on litigation matters that are ongoing." Mr Dolan said the work of the safety bureau was not intended to support legal action but to find out what happened so as to prevent it from happening again. If found, the flight recorders would be recovered. There is a plan to recover human remains but no plan to raise the whole aircraft, he said. "I am hoping, although it will be a sad moment, that in the next little while we will be able to tell the Burrows family and others that we have been successful in our search, and as a result we have the sad news that we have located the last resting place of their loved ones," he said.