Civil Aviation Authority safety investigator Peter Stevenson-Wright spent most of yesterday, the third day of an inquest into the death of helicopter pilot William Bruce Andrews (49) before coroner Brigitte Windley in Queenstown, giving evidence and being cross-examined.
Mr Stevenson-Wright told CAA counsel Duncan Ferrier he stood by the regulator's final report, which found it ''likely'' Mr Andrews inadvertently flew into cloud, became spatially disoriented and collided with terrain.
That was in contrast to an email he sent to coronial officer Senior Constable Grant Nimmo, of Invercargill, in July 2014 in which he stated evidence ''still favours the [belief] that the pilot most likely suffered a DVT that probably partially incapacitated him [and caused] him to attempt to make an immediate landing''.
Mr Stevenson-Wright told the inquest that at that time he had only just returned from sick leave to find he had received GPS data from the Australian Transport Safety Bureau.
At the time he received the email from Snr Const Nimmo, he had had only a ''cursory look'' to ensure data had been recovered.
DVT had been raised as a possible cause early in the investigation and Snr Const Nimmo had asked if there was anything on which the coroner should be updated.
Mr Stevenson-Wright told Mr Ferrier that with the benefit of hindsight he regretted making that comment.
''I was [eager] to update the coroner ... and perhaps I shouldn't have been so [eager] to do so. I should have delayed that response until I'd had time to analyse GPS information.''
He said the CAA's investigation had been ''thorough'', but admitted to Ms Windley there had been ''some omissions'', including a failure to obtain Mr Andrews' medical records.
Mr Stevenson-Wright said the medical centre that held the records had been emailed, but there had been no response.
''In hindsight, we should have realised that that was not part of our information that we should have, at least, reviewed.''
CAA staff collaborated to arrive at the likely cause of the crash after analysing information available, including the GPS data, photographs taken by the search crew that night and the scene examination.
''He [Mr Andrews] had no intention of flying into cloud ... entering cloud inadvertently can happen at any time and aviation history is full of examples ... where very experienced and competent pilots have done so.
''It's just a case of getting caught out as far as that goes ... nobody is immune from getting caught out.''
Data had shown Mr Andrews was flying ''very carefully'' after crossing the ridgeline into the Glade Burn and then the helicopter lost ''a little bit of power''.
It then turned to the centre of the valley, away from the terrain and entered a steep descent in a left-hand turn, ultimately colliding with the terrain.
Mr Stevenson-Wright said the flight path and departure from a controlled and deliberate flight to a rapid descending turn led him to believe Mr Andrews was flying between cloud layers when he became spatially disoriented.
The attitude of the wreckage, in a nose-up position on the 40deg scree slope, indicated there was a ''level of input at the very last moment'' from Mr Andrews.
''An out of control helicopter is just going to hit the slope,'' he said.
When asked by Ms Windley, Mr Stevenson-Wright confirmed he could not rule out the possibility of other factors contributing to the crash, including a medical event.
The inquest continues.
