The family of missing Malaysia Airlines flight MH370 pilot Captain Zaharie Ahmad Shah have rejected claims he was a rogue pilot on a suicide mission.

Speaking on ABC's Four Corners programme, the pilot's brother-in-law Asuad Khan said he would fight the authorities if they consider making him a scapegoat for the aircraft's disappearance.

"If they blame him I'll fight. I just won't sit down, keep quiet," he said. "Because if you say that he wanted to commit suicide in the Indian Ocean, I say prove it.

"If he wanted to commit suicide he wouldn't want to kill 238 people with him? Why would he be so stupid? He is not.

"He was not suicidal. We enjoy our life to the fullest because life only happens once."

He also denies claims of the captain committing suicide for life insurance.

"If you are talking about life insurance he didn't have one. He didn't believe in it so why would he want to commit suicide?" he said.

"Why would a person in their right mind want to commit suicide?

"He had a good life. He had a lot of money, and he loved his daughter very much."

Khan raises questions about the role of the military at the time MH370 veered off course.

"When I heard about this plane going missing I said, 'What happened to our Air Force? Are they sleeping or are they working?'," he said.

"Because as we know, even if you [turn] off the transponder, the primary radar still can detect the plane.

"I may be stupid but the primary radar will detect the flight object and MH370's flying so I became dumbfounded.

"I said, 'Look, if this is how they say they are defending our country, man, I'm worried."

During the programme he reveals the trauma of his sister, Faizah Khan, when Malaysia police quizzed her over Shah's last movements and his state of mind before piloting the plane on March 8.

Missing Malaysia Airline MH370

"The first person she called was me. When she called me, my wife could hear that she was crying like hell.

"On that day, [the plane disappeared], my sister told me he was repairing the door for the bathroom," adding that he was a 'sane man' and was not "crazy".

The ABC programme also includes a forensic reconstruction of the disappearance of the plane, along with an interview with Malaysian minister of defence and acting transport minister Datuk Hishammuddin Hussein.

It comes as Chinese navy survey ship Zhu Kezhen prepares the next phase of the search for the missing plane.

The ship is going to start mapping the seabed off the west Australian coast from Wednesday, said the Australia's Joint Agency Coordination Center.

According to documents released last week, the Australian government will be budgeting AU$90 million (£50 million) for its lead role in the search, which so far has not find any trace of the missing plane.

The actual cost could differ, however, depending on the extent of underwater submarine services, the length of the search and the contributions of other countries including Malaysia and China.