Paul Clifford was diagnosed with bowel cancer in 2013. But there was one thing he was determined to do before time ran out. To take his two-year-old son, Archie, and family to see Mickey Mouse in Florida.

Against the advice of doctors he made the trip last month with wife Clarissa and stepdaughter Tahlia.

But two weeks ago, as Paul's health deteriorated, they were forced to cut the visit short by a week and headed back to Sydney from Los Angeles.

Also on board flight QF12 was pro-euthanasia campaigner and Exit International founder Dr Philip Nitschke, nicknamed "Dr Death".

In a legal battle in December, he lost a move to win back his right to practise medicine. In a decision Dr Nitschke is appealing, a tribunal ruled that he was "a serious risk to persons and could lessen public confidence in the medical profession".

Try telling that to Clarissa Clifford.

Two hours out from Sydney her husband's health deteriorated.  The Central Coast family had saved enough for Paul to have some comfort in business class while Clarissa, Tahlia, 14, and Archie were further back in economy.

Mrs Clifford, a teacher, said that a "wonderful" flight attendant found someone to assist when her husband took a turn for the worse.

It was Dr Nitschke who swapped places with the passenger adjacent to Mr Clifford and slid into the seat offering his assistance – monitoring his heart rate and breathing.

She said: "He [Dr Nitschke] kept comforting him and holding his hand and made sure he was alert and responsive. I was happy that he was there."

When the plane touched down, Dr Nitschke offered to accompany Mr Clifford in a waiting ambulance to Royal North Shore Hospital while Clarissa escorted the children and collected baggage.

Mrs Clifford joined her husband at his hospital bedside but he died just three days later.

Despite her loss and having to organise the funeral, Mrs Clifford wasn't so busy that she couldn't find time to publicly thank Dr Nitschke for what he had done.

She friended him on Facebook and put up a message on his Facebook page explaining how their paths had crossed, saying, "The universe works in mysterious ways!"

Her post said: "You showed me you have qualities including moral and spiritual dimensions of medical practice – in particular [the] practices of care for people at the end of life.

"I cannot help but to mention how ironic it seems that in your own profession ... you encounter terminally ill patients much the same as my husband was often, yet we met simply by 'coincidence' flying home to Australia.

"Thank you for being you Doc!"

Dr Nitschke, currently rehearsing in London for a satirical show on euthanasia at the Edinburgh Festival Fringe, said it was 4am when he was approached to help.

"The flight attendant came up to me and said 'we have this patient, would you come and see them?'

"I still don't know why that happened other than that there were no other doctors on the flight," Dr Nitschke said.

"I said, 'Yes, but you know I am suspended.'

"They said, 'we don't care' or something along those lines."

Dr Nitschke said a decision on his appeal to the Darwin Supreme Court over his suspension to practise was expected "any day".

Mrs Clifford added: "Qantas was phenomenal. Their help was overwhelming and I was so grateful.

"It was always Paul's dream to take Archie to Disney World, that's pretty much how he got through 2½ years of cancer.

"I am just so happy that those are our final memories together.

"He really did get to do what he wanted to do," she added.

"Not many people can say they had that chance."