Tauranga-based Sunair Aviation has won the right to fly again after being grounded for six months.
Owner Dan Power said the lengthy time out of the air had cost the airline "millions" and it could be several months more before it could resume full passenger services because of an acute pilot shortage.
The company will recommence daily flights between Whangarei and Kaitaia, Hamilton and Tauranga on April 21 but difficulty recruiting at least four pilots would delay resumption of flights between Hamilton, Tauranga, Rotorua and Gisborne.
Power is upset about the time it took the Civil Aviation Authority to work through maintenance and other issues which he said should never had resulted in suspension of the airline's air operators certificate, and the certificate of airworthiness for its fleet of 13 aircraft.
It's been a long winded affair to return to the skies and the down time has been expensive for the company."
"I complained to the authority that they were not working with us in a timely fashion but they are of the view that they were, and did all they could."
Irene King, part of a group of aviation consultants who worked unpaid with Sunair to help them get back flying, is also critical of CAA's handling of the case.
"We didn't get a response to letters, we got told that staff are not available, they're on leave, they're too busy.
"We've got a pretty good idea of what unsafe looks like, but we've not been able to see anything of any significance or substance anywhere and we have been over it [Sunair] for months."
CAA deputy director of air transport Mark Hughes is adamant that Sunair's suspension was warranted due to safety concerns which arose during a comprehensive audit and subsequent investigation of the company's operations.
He said those concerns had been addressed by a change of senior management, improved maintenance control procedures, rectification of aircraft airworthiness deficiencies and improved management systems
The grounding last September was Sunair's second in less than a year - it ceased operations for six days in 2016 when CAA became concerned it did not have the management structure to support the growing airline.
The most recent action against Sunair came under close scrutiny after it was revealed that CAA deputy chair Peter Griffiths had told Barrier Air - which he part owns - about the grounding before Sunair was officially notified, and suggested Barrier Air offer to take over Sunair's services while it was unable to fly.
He subsequently resigned his position on the CAA board which then commissioned Mary Scholtens QC to carry out an independent investigation into the confidentiality breach.
She also looked into other potential conflicts of interest resulting from Griffiths 25 per cent shareholding in Barrier Air, and his directorship and shareholding in Kaikoura-based Wings Over Whales run by his son and daughter-in-law.
That included suggestions he used his influence as a board member to get regulatory action taken against some of his competitors, or used information obtained as a board member to his commercial advantage.
Scholtens concluded that Griffiths had - albeit inadvertently - used his position to attempt to gain an advantage by taking over Sunair's passengers.
However, she said she had no reason to doubt his explanation that he read the email message about Sunair's suspension quickly and did not pick up the point that Sunair was yet to be advised of the action.
Scholtens said there was no evidence Griffiths knowingly influenced or attempted to influence regulatory decisions.
But she recommended the board consider whether it should appoint board members with current financial interests in the aviation industry because of potential "issues of perception, and possibly conflict."
At its March meeting the CAA board decided it would not support the appointment of anyone with interests in the aviation industry (ownership or investment holdings), and if they were acquired post-appointment, the member would have to resign.