An aviation group says the Government-ordered inquiry into the Civil Aviation Authority isn't sufficiently independent.
Transport minister Phil Twyford says he wants an ''honest and robust'' assessment of the authority's regulatory and internal culture.
But his selection of the Ministry of Transport to do the inquiry has Aviation New Zealand worried.
"'I don't think the MoT is sufficiently independent,'' said the industry body's chief executive John Nicholson.
''The Ministry of Transport has oversight responsibilities for the CAA. It is essential that any suggestion that the ministry had any prior knowledge of such allegations about inappropriate behaviour and culture be ruled out,'' he said.
Claims by staff of bullying and sexual harassment have emerged over the past two months and there is ongoing disquiet in the general aviation sector about how consistently rules are applied.
Nicholson said that given the nature of the allegations and the importance of providing a safe and supportive environment for those involved, so that their claims can be fully investigated, an organisation well versed in undertaking such investigations should be called in.
Twyford said he had confidence in the MoT being able to run the inquiry and said it would use independent, external consultants to look into the staff culture claims.
The ministry's manager of governance and commercial, Ngaire Best, said the inquiry was aimed at establishing whether there are, or have been, any significant areas of concern regarding workplace culture, and how the board has responded to the concerns.
''We also want to be assured the board have the appropriate resources and strategy in place to ensure the wellbeing of all staff, while maintaining, and building, the authority's people capability.''
Last week Twyford took a swipe at board chairman Nigel Gould for questioning the motives of whistleblowers who had come forward. The minister said he would raise the matter with him.
Best said the investigation had been prioritised by the ministry.
''The terms of reference and appointment of external specialists will be confirmed shortly, together with a proposed timeframe. Any budget allocation for the use of external specialists has not yet been finalised,'' she said.
The CAA says it ''welcomes'' working with the MoT on the issues that have been raised.
Twyford said it was important ''to build and maintain public trust in official government agencies like the CAA especially when they are entrusted with the integrity of aviation safety''.
Aviation New Zealand says it also disappointed by what it calls a lack of vision in the overhaul of the Civil Aviation Act and Airport Authorities Act.
When Twyford released a draft in May, he said the changes covered every part of the aviation sector.
"Measures to improve safety include a new drug and alcohol management scheme for people who work in the sector, clearer powers for aviation security officers as well as amendments which take into account new technology like drones,'' the minister said then
But Nicholson said it was a ''basically a rehash'' of current law and did not position the industry for growth over the next 20 to 30 years.
''Given the consultations that occurred in 2013 and 2014, we expected better. In submissions this time, industry is making many of the same points again.''