Complaints were made about hot air balloon pilot Lance Hopping being too impaired to fly, and cheating on his pilot's test before the Carterton balloon disaster, but no action was taken.
The Civil Aviation Authority (CAA) revealed the previous allegations at a coronial inquest into the Carterton tragedy this afternoon.
But despite the serious allegations, including that on one occasion Mr Hopping was "too pissed and/or too high" to fly, the CAA told the inquest no safety review was conducted.
At the inquest at Wellington District Court today, the lawyer for some of the families, Alastair Sherriff, produced a CAA report, undertaken two months after the fatal crash, into how historic allegations had been handled by the authority.
Mr Sherriff told reporters outside court today that the CAA gave up the report "involuntarily" and today was the first time it had been made public.
During questioning in the inquest, Chris Ford from the CAA confirmed there had been a number of Aviation Related Concerns (ARC) about Mr Hopping in the years before the crash.
Those concerns included an ARC on February 4, 2010 about a balloon flight that was cancelled because Mr Hopping appeared "too pissed and/or too high to perform piloting duties", the report said.
That incident was not isolated, the report said.
"In one incident within the previous two years, an on board crew person had to take over the controls of the balloon because Mr Hopping was incapable of landing it on his own due to impairment."
Another related to an unauthorised notebook being found on the pilot as he was sitting a flying exam.
"A layman would call that cheating, wouldn't they?" Mr Sherriff asked Mr Ford, who agreed.
The exact test was not known, nor was the date it was taken, but Mr Sherriff told reporters it would have been sometime before 2010.
The two CAA investigators tasked with looking into the ARCs decided the information they had was "insufficiently reliable" to justify an interview with Mr Hopping, the report said.
"This was because the information provided was of a hearsay nature, from persons who may have had their own agenda in making the assertions.
"[And] the police could not provide any relevant information."
A medical certificate in 2004 pointed to Mr Hopping's "binge drinking" and a note that he should drink more moderately was made.
CAA investigators decided to monitor Mr Hopping's balloon operation on an ongoing basis, the report said.
Mr Sherriff suggested to Mr Ford the two investigators knew Mr Hopping, but Ford did not know if that was the case.
Mr Sherriff said if the information had been in the media in 2010, nobody would have flown in a balloon with Mr Hopping.
"That's a fair assessment," Mr Ford replied.
Mr Ford said the CAA was a "changed organisation" since 2010, with a new director, board and senior management team.
"Additional resources have been assigned, specifically related to investigations or ARC concerns," he said.
Mr Sherriff asked Mr Ford if the CAA had let the public down in the way it dealt with the ARCs.
"There is no information available to me to say that was the case," Mr Ford replied.
He agreed with Mr Sherriff that over the 15 years that Mr Hopping was a pilot, there was no CAA safety review into him.
The Transport Accident Investigation Commission had already established that Mr Hopping's errors were ultimately responsible for the crash.
At the time, Mr Hopping had cannabis in his system.
His pilot's medical certificate had also lapsed.
The inquest continues.