It was likely a student pilot was flying a Robinson helicopter when it broke up in midair and crashed near Queenstown in 2015, an investigator says.
A coronial inquest into the crash, which killed James Patterson Gardner (18), of Queenstown, and instructor pilot Stephen Combe (42), of Wanaka, entered its fifth day in the resort yesterday.
Continuing to give evidence was independent accident investigator Andrew McGregor, who said damage to the R44’s "cyclic" control stick caused by the impact of a main rotor blade on the cabin, or "mast bump", and the men’s injuries, indicated Patterson Gardner was flying the aircraft when it crashed in the Lochy River valley on February 19 that year.
The pair had finished a training exercise in the upper valley and were returning to Queenstown, Mr McGregor said.
"A flight home is more straightforward than the training exercise, so it’s likely the student was flying, for that reason alone."
His conclusion differed from that of the Transport Accident Investigation Commission’s report into the accident, released the following year, which said Patterson Gardner was "as likely as not" to be flying at the time.
Referring to evidence given by MetService meteorologist Neal Osborne on Thursday, Mr McGregor said the wind in the valley at the time of the accident was light, although abrupt changes in wind speed and direction were possible.
Light turbulence would be expected at the time of the accident, and Mr Osborne’s report did not support the possibility of moderate turbulence.
However, it "cannot be ruled out" an abrupt wind gust of 20 knots generated an episode of moderate turbulence and an unexpected low-gravity encounter, he said.
Evidence given earlier in the inquest described how a low-gravity condition is a potential contributing factor to a rapid right roll, mast bumping and inflight break-up of Robinson helicopters.
The inquest continues on Wednesday and ends on Friday.
