A helicopter had a near-miss with skydivers after refueling without clearance from the aerodrome.

An official investigation has concluded: "The helicopter pilot was completely unaware of any skydiving taking place".

More details have come to light about the frightening incident on January 4 this year, which is one of dozens of near misses in New Zealand skies in recent years.

A report by the Civil Aviation Authority (CAA) on the near-miss has been released to the Herald on Sunday under the Official Information Act.

Two helicopters operated by the same company were flying together when they diverted to Franz Josef Aerodrome to refuel, after the lead pilot contacted a local operator who confirmed the airport had fuel.

However, no contact was made with the privately-owned aerodrome to get approval to land.

"Had the pilot contacted the operator, the pilot would have received a briefing on the skydiving activity taking place and the location of the parachute landing area in use," the CAA report stated.

After taking off from the fuel pumps, one helicopter performed a slow orbit to give the other pilot time to catch up.

The orbiting pilot was contacted by radio by the plane the skydivers had jumped from, and told to leave the area immediately.

"The helicopter pilot was completely unaware of any skydiving taking place," the CAA report stated. "Only after the radio call did the helicopter pilot noticed the tandem parachute approximately 100 meters away."

Because of the incident signage warning of skydiving has been put up at the aerodrome fuel pumps.

"It is suggested that a prudent pilot would have vacated the aerodrome via the circuit, therefore, avoiding the parachute landing area altogether," the CAA stated. "This is also a good opportunity to remind all pilots of the importance of making appropriate radio calls at uncontrolled aerodromes."

The CAA declined to release the full report and associated photographs of video, and would not name the operators involved, saying to do so could discourage pilots from reporting near-collisions in future.

Franz Josef Glacier in the South Island. (Photo / file)

James Meldrum, chief executive of Skydive Franz Josef, confirmed the incident involved the company's skydivers.

"Our tandem masters saw this occurring and entered a holding pattern, while we contacted the helicopter pilot, who very promptly vacated the area. The skydivers landed as usual, in their intended landing area, although we have a secondary landing area available.

"We take safety seriously and we've taken steps to reduce the likelihood of this happening in the future including signage on the fuel pumps, and talking to itinerant operators advising them of our operation and where our landing areas are."

The Franz Josef Glacier air space is very busy during peak season, with multiple flight and helicopter operators and more than 70,000 passengers a year.

In March last year there was another near-miss at Franz Josef between two helicopters. And local pilots were angered when United States Air Force F-16s flew close to a helicopter during an air show in March this year.

The CAA has recorded 50 near-miss incidents nationwide since January 2017. Reported near-collisions increased by more than 50 per cent last year and the CAA is developing a strategy to try and reduce such incidents.