An official finding that pilot error was the most likely cause of one of New Zealand's worst air crashes has been challenged by the pilot's family and business.
A Transport Accident Investigation Commission report into the crash last June - in which seven leading scientists as well as pilot Michael Bannerman died on an approach to Christchurch Airport - says it was probably caused by him becoming distracted.
Investigator-in-charge John Goddard found the 52-year-old pilot's cellphone was turned on three minutes before his Piper Chieftain clipped some trees and hit the ground, and that he failed to monitor his altitude after beginning the approach too fast and erratically.
But Mr Bannerman's family and his partner, fellow Air Adventures director Janice Williams, disputed key parts of Mr Goddard's report.
They described Mr Bannerman as a cautious and conscientious pilot not given to taking shortcuts, and said indications of malfunctioning instruments were not investigated adequately, a claim Mr Goddard denied last night.
The family said the aircraft's consistent position below a recommended glide path in its descent to Christchurch Airport strongly suggested the pilot was receiving incorrect information.
It claimed aircraft instruments found to be pointing down suggested they were indicating incorrectly to the pilot that the aircraft was above the glide slope and that the aircraft therefore needed to be lower for a safe arrival.
"It is our firm belief Michael was misled by malfunctioning instruments ... "
They also contested Mr Goddard's dismissal of wake turbulence from a preceding aircraft, a Boeing 737, as possibly destabilising the Chieftain.
Mr Goddard was too busy last night to comment, referring the Herald to his report, which noted that Mr Bannerman's aircraft was three minutes and 50 seconds behind the Boeing.
This was substantially more than a three-minute separation prescribed for the avoidance of wake turbulence.
The report said any deficiency in navigation aids transmitted electronically from Christchurch Airport was unlikely, as they worked for the Boeing's landing and were found to be operating normally when checked afterwards.
Mr Goddard acknowledged in the report that the possibility of a faulty glide-slope indication by the Chieftain's own instruments was unlikely to be resolved.
But while it was possible the pilot's cellphone might have caused faulty indications, tests on the aircraft's altimeter showed it was working normally, and was not susceptible to electronic interference
Here's the official report
http://www.nzherald.co.nz/pdf/chieftanreport.pdf