Invercargill Airport general manager Nigel Finnerty said the study was a risk assessment of the airspace and how aircraft are managed.
"Through that you build a current understanding, and build what the risks are. And then, look at the mitigation and how you manage those risks — one of the ways now is through air traffic control."
While initially that was done with Airways New Zealand, which confirmed last month it would cease air control services at seven New Zealand airports. Those included Invercargill Airport and the airfield flight information services at Milford Sound Piopiotahi Aerodrome.
"Over the last four weeks we’ve been out looking at the market and understanding how we do that work," Mr Finnerty said.
Airways announced yesterday a working group with Gisborne Airport, Hawke’s Bay Airport and New Plymouth Airport would collaborate to plan for how air traffic services could be provided to those regions.
An Airways representative said it was not accurate to say they were reconsidering decisions.
"There’s simply a process to work through which means options other than withdrawal are also on the table."
The Civil Aviation Authority will make the final decision on what type of service is needed for each airport.
Alternatives to a full air traffic control service include an Aerodrome Flight Information Service or operating as an unattended aerodrome. Airways is also investigating digital solutions.
