The father of Floyd Fernandes, killed in the gorge tragedy, didn't want a film to be made.

The father of a boy killed in the 2008 Mangatepopo Gorge tragedy says a film about the event has upset his family.

Francesco Fernandes' son Floyd was 16 when he was killed in a flash flood that also took the lives of five other Elim Christian College students and their teacher.

The students were canyoning at the Hillary Outdoor Education Centre when they were swept away and Coroner Chris Devonport later ruled the tragedy avoidable.

The 10-year anniversary of the deaths passed in April.

READ MORE:

* Review: In A Flash

* In A Flash: Controversial drama relives deaths of Elim students and their teacher

* 'A tragedy that could have been avoided'

* Elim students and teacher remembered 10 years on

A film dramatising the tragedy, In A Flash, aired on Sunday night as part of TVNZ 1's Sunday Theatre series.

TVNZ The 2018 Sunday Theatre is screening on TVNZ1.

Francesco Fernandes says reliving his son's death has been painful for the family.

"It's a terrible thing. I really can't understand why people do this after 10 years."

The production company behind the film, Screentime New Zealand, consulted with the families of the deceased students when making the film.

A member of the production came to visit the Fernandes family in Queensland, Australia where they now live. The family was sent a script of the film, and a DVD of the finished movie.

"We didn't even read the script, it's still lying at home, because it's very hard to go through something like that," Fernandes says. "We have the DVD of the film but nobody's ever looked at it."

Screentime has agreed not to use Floyd's name or representation in the film.

Fernandes still wishes it wasn't made.

"It's very unfair, that people don't treat you the way you should be treated. They don't really care what you feel as long as somebody's getting the funding and somebody can make the movie. Nobody really cared for what we were undergoing or what we wanted."

He says he would have tried to stop the film if he had the time for a legal battle. He prefers the $2.9 million in taxpayer funding the film received through New Zealand On Air was spent training outdoors instructors to prevent a similar tragedy occurring.

"I really don't think [the film] could help anyone. I would like to know any of the families who it has really helped, because I know it hasn't helped us. Just listening about it, everybody's upset. My mother is in New Zealand still and she's upset by it," Fernandes says.

Supplied In A Flash dramatises the real events of April 2008, when six students and a teacher from Auckland's Elim Christian College were killed in a flash flood.

Screentime CEO and In A Flash producer Philly de Lacey acknowledgestwo of the students' families - the Fernandes family and the family of student Tom Hsu, who live in Taiwan, did not support the film.

But the families of the other flood victims wanted the film to be made, she says. They had input into the script, as had rescuers and some of the students who survived the flood.

De Lacey says the fact that the Fernandes and Hsus did not live in New Zealand was significant. She had asked the film's distributors to ensure it wasn't sold into Australia or Taiwan so the families who didn't support the film wouldn't stumble upon it on television.

"Obviously there's a huge amount of hurt and heartache, but we felt that because they didn't live in New Zealand and because the other family members did and some of them were very, very keen to go ahead - on the balance of that we felt it was more positive to go ahead with it than not."

Screentime has made films from a number of true life stories including Resolve, about Chris Crean's ultimately tragic stand against the Black Power gang.

"Almost 99 per cent of the time the reaction we've had is that it's been cathartic and it's helped in the healing process," de Lacey says.

"We've always done our best to consult with people and treat these things as respectfully as possible. So it was really important to us when made this film that we set out to make it a tribute to the children, and I really believe we've done that.

"I think that their bravery - and talking to a couple of survivors, and what they felt and the experience they went through, those kids were total heroes and were incredibly brave against the odds of what they faced. And that's what we wanted to show in the film, we wanted it to be a tribute to them."