Key Points:

A senior aviation figure has described flying into some of the country's busiest uncontrolled airports as being like "Russian roulette".

Peter Vincent, managing director of Vincent Aviation, said last weekend's tragedy at Paraparaumu Airport might not have happened if the airport had a manned flight tower. Pilots were very worried about near-collisions at other airports that had lost their flight services in the past 20 years, particularly Ardmore and Taupo, he said.

Pilots using Paraparaumu have described their own near misses at the airport on an internet forum. One, posting under the pseudonym Weekend Warrior, said he had had three incidents in two years, involving near-misses with a helicopter, a glider tug and a microlight.

"I would suspect you wouldn't talk to many pilots flying out of these airports a lot who haven't had one or sometimes two near misses," said Vincent. "There have been many, many near misses and I am sure there will be more. I am aware of many close calls at Ardmore, Taupo and Paraparaumu."

Vincent said he had spoken to a pilot in the past week who had emerged from clouds over Paraparaumu to find a Cessna "right in front of them".

"They just managed to miss it."

Civil Aviation Authority director Steve Douglas said no safety concerns had been raised with him since the Paraparaumu accident. But the internet forums suggest some pilots don't report close-calls, for fear of being prosecuted themselves.

The Herald on Sunday has uncovered statistics from the CAA's own database showing there were 226 "airspace incidents" in the three months to September 31 last year, compared with 188 incidents in the same period the previous year. Although most were minor, a second safety report reveals there were nine "near collisions" in the six months to December 31, 2005.

The CAA said there were 12 reported near-misses at airports last year, 20 in 2006 and 15 in 2005, although these were at controlled airports.

The decision to withdraw flight services from some airports was made by Airways New Zealand, a separate state-owned enterprise which looks after air traffic control. Ardmore, which has up to 250,000 aircraft movements a year, lost its flight tower presence in 1988, Taupo in 1996 and Paraparaumu in 1997.

An Airways NZ spokesman said airports were run on a user-pays basis and operators had raised concerns about the cost of flight services. He said Airways was told by the CAA there were no safety issues and the services were then axed.

The CAA said it carried out aeronautical safety reviews before each decision. Manned towers were replaced with mandatory radio broadcasts between pilots.

The CAA said the mandatory broadcasts required pilots to report their height, position and intentions at regular intervals "so that all aircraft in the vicinity can visualise where they are in relation to other traffic".

"In addition, there are a number of general flight rules that relate to keeping a proper lookout, and being seen. These include remaining clear of obstructions, and not conflicting with other traffic in the airport circuit, or with aircraft arriving under instrument flight rules."

Vincent said he thought it was a mistake to take the flight services out of Paraparaumu, Ardmore and Taupo. He described the person in the flight tower as an airport's "eyes and ears".

"In the good old days there were flight services in every airport NAC used to operate to. It was a great service.

"In a place like Paraparaumu it's very loose. If there had been flight services there as there used to be, there's a strong possibility that what happened would never have happened. At least they would have had a fighting chance."

Mark Rammell, president of the Air Line Pilots' Association, agreed. He said the association had taken a judicial review against the CAA's decision not to implement Air Traffic Services at Taupo airport.

Last weekend's accident had focused attention on the risks at airports, he said. "Absolutely, a mid-air collision over an uncontrolled, busy airfield highlights the potential problems out there.

"Quantifying at what level there is a problem is difficult. Out of this [investigation] will come questions around whether busy aerodromes should have services or not."

Paraparaumu Airport manager Richard Baldwin, a pilot for 30 years, said he had "limited knowledge" of the weekend's accident and did not want to comment directly on it.

He said it was up to the pilots to use their mandatory broadcasts to maintain awareness of what was happening around them in uncontrolled airspace. "It's under the absolute control of the pilot in command. Decisions are based on best judgement. It's their hide."

Baldwin said the airport's tower had been unmanned for 11 years but radio communications had improved as a result. He was "comfortable" that existing measures kept pilots safe.

But people on the pilots' internet forum have called for tighter controls.

Weekend Warrior said flight services at Paraparaumu had kept everybody honest because they knew they were being watched.

And "Slackie" said: "Big sky theory doesn't work too well when it's full of aircraft all doing different things!"

Vincent said cost was one reason airport operators did not favour the reintroduction of flight services.

"There would be an increase in fees to people using these services, but as far as I am concerned it's a cost worth paying."

He also criticised aviation authorities for what he said was their "horribly lop-sided" focus on security rather than funding safer airports.

The CAA's budget is $27 million a year compared with the Aviation Security Service's $56m.

"To be quite frank, if I am flying into one of these airports I would be far, far, far more concerned I would be killed or injured in a mid-air collision than the possibility of someone trying to slice me up with a knife or whatever," Vincent said.

Douglas said the authority responded to concerns by reviewing safety measures at individual airports. Taupo will be looked at later this year.

He said there was no plan to review measures at Paraparaumu.