"He was wearing an oxygen mask and at one stage they were using a defibrillator on him," he said.
According to the Cairns Post, airport sources told the publication that the drama on board the plane continued after it landed, describing the emergency situation as a "comedy of errors" because no ground crew were available to assist in the removal of the body at that time of the morning.
It is understood that due to the time of day, accessing the aircraft became problematic while the plane sat on the tarmac.
According to an airport source, who spoke to the Cairns Post, the pilot of the aircraft didn't want passengers to use an aerobridge and risk seeing the deceased body. So instead, the crew sourced a set of stairs for the aircraft — but what arrived were too small.
"They found a small set of stairs, which they put up to the aircraft door," the source said.
"They were totally insufficient. The paramedics had to put their kit on top of those stairs, and stand on that, and they were still only chest high to the door."
"They had to climb into that aircraft to attend to that matter."
It is understood the paramedics had to remove the body from the aircraft via the stairs.
News.com.au has contacted Air New Zealand for comment.
On Monday, an Air New Zealand spokeswoman said there had been a medical emergency on board the aircraft.
"For obvious privacy reasons, we're not able to provide further information about the passenger," she said.
She said the aircraft continued on to Auckland, and arrived about two hours behind schedule.
This story was originally published by The Cairns Post.