One of the country's leading aviation medics says many GPs who have patients who are pilots are ignorant about what health conditions they should report to the Civil Aviation Authority.
The Transport Accident Investigation Commission (TAIC) has reopened its inquiry into a 2015 crash after receiving new information about the pilot's mental health.
The helicopter crashed in bush near Queenstown in February 2015, killing an instructor and a student.
An initial report into the cause was inconclusive, but last year the commission received new evidence that the pilot was mentally unwell in the months before the crash.
TAIC is now recommending a person's occupation be added to medical records to allow better monitoring of people in safety-critical occupations who have potentially adverse health conditions or medications.
It also wants GPs to be made more aware of their obligation to report it to the relevant authority when a patient has a condition which could pose a safety risk because of their job.
Dr Dave Baldwin said when a pilot applied for a medical certificate, they had to fill out a four-page declaration which should pick up if there was a problem.
"Then they have to sign that document in front of the doctor so there should already be a high level of awareness that this is a legal document to the pilot who is presenting.
"So most doctors that I know who examine pilots, given the full noise, you don't tell porkies on this, if you know what I mean."
Dr Baldwin said he had experienced GPs not reporting conditions they should they have in the past.
"The patient had honestly filled the form in, but put down that he was on an anti-depressant which was a real no-no at the time. So I got onto his GP and said 'you know he's a pilot' and they said 'oh, we thought he'd be all right to fly with that'.
"So there is an ignorance out there but I wouldn't overly blame the GPs who are doing great work."
Dr Baldwin said the existing system was reliant on patient honesty.
"I few weeks ago I had an epileptic turn up wanting a medical and I said I'm really sorry to bust your dream but you just can't fly buddy like no one in the world would give you certification so off he trudged.
"Now what I did was let CAA know that if this guy ever applies this is the detail, but he could go to another examiner and not declare it."
Call for stricter certification
The inquiry into the 2015 crash found the pilot applied for a medical certificate just two weeks before the crash, but did not declare the medication he had taken or mention that he had been having psychological or mental health problems.
Chief investigator Tim Burfoot said there needed to be a stricter certification process that would ensure potentially serious health issues were identified.
There was anecdotal evidence that some pilots had circumvented the system by using different doctors to avoid mentioning some health issues, he said.
However, the report showed this pilot did not use more than one GP.
Doctors are required to report to the Civil Aviation Authority (CAA) if they think a pilot has a condition that makes them unfit to fly.
But Mr Burfoot said many GPs were not aware of this and the commission wanted the CAA to remind them of the rule.
In a statement, the authority agreed to this.
CAA said it would conduct a review to see if it could become better at identifying potentially serious health issues. The review would be completed by 1 December 2017.
Occupations listed on national electronic health database
Internationally there are moves to improve medical certification systems after an air crash in the French Alps. One hundred and fifty people died when a German pilot who had suffered from severe depression crashed the plane.
Mr Burfoot said the commission also made recommendations to the Ministry of Health, encouraging it to include people's occupations on a proposed National Electronic Health Record.
The ministry said currently a person's occupation could be collected on local IT systems, but there was no nationally linked up system. It said it was pursuing a business case process into the viability of an electronic record.
The Royal New Zealand College of General Practitioners said these were significant recommendations and it wanted to consider the implications before commenting further.
No-one from the Airline Pilots Association was available for comment.