Will the UFOs return to Kaikoura?

Almost 40 years ago, Kaikoura was visited by UFOs for Christmas and New Years - and they've been seen occasionally ever since then.

Their visits remain one of New Zealand's biggest mysteries, and caused an international stir.

In 1978, Safe Air pilot Bill Startup saw something out the window of his Argosy freight plane that has baffled UFO sceptics and believers to this day.

As he flew over the Kaikoura mountain ranges in late December he reported seeing strange lights and flying objects.

"What it was, we don't know, that's all. I wish I knew," he says.

Journalist Quentin Fogarty was on the plane on the night of December 30, 1978. He described what happened when UFOs appeared in front of the aircraft.

"On the flight down, what we basically saw were pinpricks of light that turned into great globes of light, and they were airborne, and they were between us and the coast because we could see the coast and we could see the sea, and we could see these things shining down," he says.

Once they landed in Christchurch, cameraman David Crockett restocked with better film and they headed back to Blenheim. The lights followed them almost all the way.

The reports gained further support when two separate radar systems tracked the mysterious lights at the same time.

John Cordy was the radar operator on the night of the first sightings on December 20.

"We saw some little targets on our radar just down off Blenheim, Cape Campbell way, and we joked that it was Father Christmas having a practice run with Rudolf in the front, because it was just before Christmas," he says.

Then the UFOs followed the Argosy freight plane.

"This target then moved toward the Argosy, turned with it, then tracked with it for a good 20 to 30 miles. The target and the aircraft were at 90 degrees to each other the whole time. And Vern Powell's aircraft said they could see a big red light that was definitely airborne."

The Ministry of Defence publically dismissed the sightings as merely an optical illusion.

However documents released by the Defence Force show this sighting was taken seriously because it might be evidence of "intruders" and launched an inquiry.

The inquiry report said that if the objects existed and the observations were correct, they were travelling at 10,800mph.

It concluded the incident could be explained by "natural but unusual phenomena" and commented: "Perhaps the most difficult aspect to explain away is the apparent concern - even apprehension - of the aircrew involved in the sightings. At present they do not seem to be prepared to accept the fact that they might have observed Venus."

Mr Startup remains unsatisfied with any of explanations.

"None of them to my knowledge or satisfaction have coordinated the visual sighting with the radar sighting," he says.

"They've said the visual sighting was squid boats, it was Venus, it was Jupiter, it was the harbour lights. You name it, they can come up with all sorts of reasons for what it was.

"But they haven't explained why I can see Jupiter, Venus and the harbour lights doing 140 knots on my radar."

The last sighting of the UFOs was in 2015. However believers in Kaikoura still keep watch each year, waiting to see if the UFOs return for Christmas.