A coroner has found the deaths of eight people in an air crash near Christchurch Airport three years ago was the result of the pilot deciding to fly alone.

Christchurch coroner Richard McElrea found the decision of Air Adventures pilot Michael Bannerman to fly without a co-pilot was a major factor emerging from the crash on the night of June 6 2003.

Mr Bannerman, 52, was flying a Piper Navajo Chieftain twin-engined aircraft carrying nine Crop and Food Research employees when it ploughed into farmland.

He was killed in the crash, along with Howard Bezar, 55, Katherine Carman, 35, Alistair Clough, 37, Richard Finch, 41, Desma Hogg, 41, Andrew Rosanowski, 37, and Margaret Viles, 53.

Two people survived with serious injuries.

The Crop and Food staff had been returning to Christchurch after a one-day conference in Palmerston North.

A Transport Accident Investigation Commission (TAIC) report in 2004 blamed pilot error as the most likely cause of the crash.

Today, Mr McElrea reached similar conclusions after conducting one of the largest coronial inquests since coroners were established in New Zealand 160 years ago.

Mr Bannerman's decision to fly without a co-pilot in marginal weather conditions and at night was "always going to test the outer limits of his competency" as a pilot flying under instrument flight rules, he found.

On a flight with a full complement of passengers just three weeks before the crash, Mr Bannerman "appropriately" flew with a co-pilot.

"Why Mr Bannerman chose to undertake the Crop and Food flight on June 6 2003 without the assistance of a co-pilot is unknown, but is very likely to have been a reflection of the difficult financial circumstances of Air Adventures and that he was the only pilot," Mr McElrea said in his findings.

Evidence at the inquest from Civil Aviation Authority (CAA) principal medical officer Dougal Watson was that having a second pilot in the cockpit gave a "one-in-100 protection factor". Evidence from other pilots had also confirmed that a second pilot would substantially reduce risk.

Risk reduction

Mr McElrea said the passengers on Mr Bannerman's aircraft on June 6 2003 "did not have the benefit of such risk reduction".

CAA rules allowed the flight to go ahead on a single-pilot basis and a competent single-pilot instrument flight rules (IFR) approach "should have and would have landed the aircraft successfully".

Safety factors in the rules allowing single-pilot IFR flight were broached by Mr Bannerman by a combination of his inexperience in IFR flying and inexperience in night flying, Mr McElrea found. The rules, nevertheless, allowed him to have the accreditation he had.

The coroner said the "other factor in that combination" was Mr Bannerman's decision to fly from Palmerston North in marginal weather conditions without discussing other options with his passengers.

Mr Bannerman had a global positioning system (GPS) unit as an aid to navigation, but was required under CAA rules to disregard the unit completely on making an instrument approach to the airport.

"The evidence would indicate that he was placing at least some reliance on it, and it is most likely that he had loaded an incorrect waypoint into the unit by a factor of 1.2 nautical miles, causing the aircraft to crash 1.2 nautical miles short of the runway," Mr McElrea said.

Mr McElrea noted that the CAA "not unnaturally" had defended its position as to the application of the rules. Deficiencies , "at least in part" were to be put into the context of a regulatory regime.

While a preferred approach to to ensure standards were met by "encouragment rather than by enforcement" might be admirable in many situations, Mr McElrea said the inquest findings had highlighted that the "tolerance factor" where safety was an issue had been "shown to be too great".