'Bring Que home' – Dad's plea to Alan Langdon

New Zealand Police say Alan Langdon has contravened a family court order by taking his six-year-old daughter out of the country.

Que and her father went missing after leaving Kawhia Harbour almost a month ago.

On Wednesday, the pair arrived in Ulladulla, NSW, after Mr Langdon claimed a broken rudder forced him to sail across the Tasman.

Mr Landgon's father, Walter Langdon, says he struggled to sleep at night but is glad his son is okay.

"Every phone call you hope it's good news," he says.

He received that news on Wednesday, that his son and granddaughter were safe. 

Walter Langdon had mixed emotions after hearing the news.

"Excited yeah and of course very angry with our son," he says.

He's angry because he believes Alan never intended to sail to the Bay of Islands as he claimed.

Alan Langdon told Newshub a broken rudder forced him to sail across the Tasman.

He's been involved in a custody dispute with Que's mother Ariane Wyler.

New Zealand Police say they're now working with Australian authorities as part of their investigation.

Child recovery expert Col Champan says he believes Que's mother, who is currently in Switzerland, is making her way to New Zealand.

Walter admits his relationship with his son hasn't been the best, but says his door is always open.

"I wish he would come back and face the music in New Zealand and bring Que with him," he says.

Walter says he wants the family reunited and wants Que to grow up in a "happy extended family atmosphere".