The two companies had competed for contracts in the past.
Sunair learned of the coming suspension from a Barrier Air pilot two hours before the authority officially emailed notice, Scholtens found.
Scholtens found Griffiths made "a thoughtless mistake" but, regardless of intent, it was "objectively a misuse of confidential information received in his capacity of a member of the board ... to attempt to gain an advantage for Barrier Air".
She found no reason to doubt his explanation that he read the message quickly and did not realise Sunair had not been informed, and that his actions were "genuinely intended to assist Sunair if possible".
Scholtens reported Griffiths told her he had been very busy when he read the email and would not have disclosed the information had he realised it was not public.
The authority's initial investigation turned up claims from some in the aviation sector that Griffiths used his influence as a board member to subject competitors to more regulatory scrutiny than Barrier Air's competitors.
Scholtens saw no evidence of that but found having a board member with a stake in an airline did pose problems and could look suspicious.
She made five recommendations, including reviews of the board's conflicts of interest policy and "no surprises" practice, and looking at the risks of having board members with financial stakes in aviation.
Board chairman Nigel Gould said the board would action the recommendations urgently.
Gould said he regretted what had happened.
"While I accept that Mr Griffiths' actions in the Sunair case were well-intentioned, they nevertheless represent a profound error of judgment by a member of the board. He has suffered the consequences of that error and will likely continue to do so for some time."
Mr Griffiths told the Bay of Plenty Times he acknowledged he made an error and resigned.
"Notwithstanding that, I think the travelling public and members of the aviation system should continue to have the utmost confidence in the integrity and most crucially the impartiality of the director and staff of the CAA."
The Bay of Plenty Times has contacted Sunair owner Dan Power for comment, as well as Barrier Air and Transport Minister Phil Twyford, but none responded before deadline.