In her formal written findings, released today, Ms Windley said that there remained a degree of uncertainty as to the cause of the incident on December 15, 2013, and was "likely to be disappointing'' for Mr Andrews' family in their quest for answers.
"Even with the best of intentions and the most diligent efforts, no investigative process is immune from unanswerable questions for which solace may only be found in the fact of a robust investigative process having been undertaken.
"Their commitment and efforts towards ensuring a robust investigation is to be respected and commended.''
Mr Andrews, who had more than 15,000 hours' experience, died in the Glade Valley after the Hughes 500 helicopter he had been flying crashed into mountainous terrain.
An inquest was held over four days in the Queenstown District Court last November during which the Civil Aviation Authority's report, which found it "likely'' Mr Andrews inadvertently flew into cloud, became spatially disorientated and had a controlled flight into terrain, was called into question.
The report had been peer reviewed and independently reviewed.
Ms Windley's findings the family had expressed their "ongoing dissatisfaction'' with the conclusions reached by the authority and the manner in which the investigation was undertaken.
They made a formal complaint to the CAA alleging the investigation team had lied during the investigation.
Ms Windley said after the family's complaint was received the CAA's principal safety adviser Alan Moselin undertook a desk-top review and found while the investigation and report "appeared to be thorough'' there were "weaknesses in the depth and clarity of the analysis of the report''.
"The deputy chief executive of the CAA, John Kay, acknowledged to Mr Andrews' family that the CAA investigation had been protracted and 'could have been better managed and conducted'.
"He concluded that while the investigation itself was not perfect, it was not fundamentally flawed, and the conclusions reached were reasonable.''
Ms Windley said the family made clear their serious concerns the conclusions reached and circumstantial scenario preferred by the CAA were not supported by the weight of the evidence obtained during the investigation.
They had invited the coroner's critique and adverse comment as to the adequacy of the CAA investigation - similarly, the authority had invited the coroner to refute allegations it "knowingly fabricated evidence'' and "distorted and misrepresented evidence''.
While neither was a legitimate function of her jurisdiction, Ms Windley said she had assessed whether there were shortfalls in the evidence before the CAA at the time its investigation was concluded.
"The body of evidence relating to the circumstances in which Mr Andrews lost his life has, to my mind, been significantly advanced in several respects from that which was before the CAA at the time of issuing the original CAA report.''
The inquest heard Mr Andrews had been complaining of a "strange'' leg pain the day of his final flight which appeared to become worse as the day went on.
Combined with recent overseas travel from Alaska and to and from Bangkok - totalling almost 53 hours' flight time - that gave rise to questions around whether or not Mr Andrews had deep vein thrombosis which could have led to him suffering a fatal or acutely incapacitating pulmonary embolism.
In the days before the crash he had also mentioned an occasional issue with his vision, the possible causes and effects of which were discussed at length.
Further, the helicopter had just re-entered service following an overhaul and had 40 hours' flight time at the time of the crash, putting it in the "unreliable'' phase of what experienced helicopter investigator Tom McCready called the "bath tub curve of reliability''.
While Ms Windley could draw no definitive conclusion on the exact cause, evidence suggested he collided with terrain when he lost situational awareness due to a "distracting medical or visual occurrence, and/or inadvertent entry into cloud''.
"In my assessment, the evidence does not allow for either cause to be entirely excluded, or the sequencing or relative contribution of either to be ascertained.
"It is possible Mr Andrews was not medically fit to fly on the day of the crash."
One of her recommendations was for the Director of the CAA and the Secretary for Transport to ensure their agencies worked collaboratively "and as a matter of priority'' to consider if there was a case to widen the scope of the reporting obligations to address a perceived gap in the definitions of "medical practitioners'' and continue developing, delivering and ensuring ready access to information and education around self-reporting.
Mr Andrews had visited his GP, Dr Stephen Hoskin, a year prior to his death to discuss an issue with the vision in his right eye and was referred to optometrist Daryl Parkes who saw him the same day.
Mr Parkes made four diagnoses, including a large right posterior vitreous detachment which, during the inquest, Dr David Baldwin of the Bulls Flying Doctor Service said "could be'' of significance and should be reported to the Aero-Medical examiner.
However, neither Mr Andrews, Mr Parkes nor Dr Hoskin reported it.
Dr Baldwin reissued Mr Andrews' aero-medical certificate on November 4, 2013 with a condition to have "half-glasses'' to assist with reading.
Ms Windley's findings said a medical condition was of aero-medical significance if it interfered, or was likely to interfere with, the safe exercise or performance of duties - that included vision disorders.
The CAA required any change in, or previously undetected, medical condition be reported to the Director of CAA or an approved CAA medical examiner.
Under the Act, there were obligations placed on both the licence holder and the "medical practitioner'' to inform the authority.
However, under the Act, Mr Andrews' optometrist did not meet the definition of a "medical practitioner''.
While Mr Andrews should have notified the CAA himself, several local pilots told the coroner they had never been to a CAA seminar or received education about ongoing obligations on a pilot to self-assess and self-report suspected changes in medical conditions.
Further, Dr Hoskin told Ms Windley he had "no recollection'' of ever being informed of, or having received training, relating to the obligations on medical practitioners to report to the CAA.
"He reported having queried three of his GP colleagues who advised a similar lack of awareness of this provision and reporting obligations,'' Ms Windley said.
"Dr Hoskin observed this was in stark contrast to the information and training he had received in relation to other reporting obligations, such as in relation to suspected child abuse, fitness to drive, and maritime medical certifications.''
Dr Hoskin noted it would not be uncommon for individuals with concerns over their vision to directly attend an optometrist and, in those cases, a GP would be unlikely to be aware of any issues.
In those situations, if an optometrist was excluded from the ambit of health professional reporting, the licence-holder needed to make a decision on whether the threshold for reporting had been met.
Further, as a general rule, Dr Hoskin said the provider making a diagnosis informed the patient and any relevant authorities.
"Therefore, even if he had an awareness of the section ... he would have assumed the optometrist was subject to the reporting obligation and that Mr Parkes would therefore have made the notification to CAA if it was in fact warranted.''
Ms Windley said it was "clear'' there was a "degree of disconnect and lack of common understanding'' among licence holders, healthcare professionals and the CAA around the threshold at which fitness to fly was called into question and when reporting was mandated.
Effective education around that was `"imperative'', she said.
Also included in her recommendations were for Ms Windley also recommended work continued to progress the "cost/benefit analysis'' of Helicopter Flight Data Monitoring (HFDM) "with a view to determining whether to mandate fitment of such in all helicopters, pursuant to a rule amendment.''
