An expert witness has questioned why a pilot did not apply an application of wing anti-ice on an aircraft before taking off from the Queenstown Airport in wintry conditions.
A 54-year-old pilot, of Papakura, who has interim name suppression, appeared for the eighth day of a defended hearing before Judge Kevin Phillips in the Queenstown District Court yesterday.
The pilot has denied operating a Boeing 737 in a careless manner on June 22, 2010, a charge laid by the Civil Aviation Authority.
CAA alleges the pilot should not have taken off for Sydney after 5.14pm because Pacific Blue rules stipulated departing aircraft at Queenstown needed at least 30 minutes before civil twilight at 5.45pm.
The aircraft departed at 5.25pm.
Expert witness Colin Glasgow, a former commercial airline pilot, Air New Zealand chief pilot and CAA airline inspector, said he would have applied wing anti-ice before takeoff and was unsure why the pilot had not considered doing the same.
The temperature was 3degC at the time of takeoff and there was rain, recent snow, thick cloud cover up to high altitudes and a cold front in the area at the time, Mr Glasgow said.
Because of the area the aircraft was exposed to potential icing and wing anti-ice should have been applied before the aircraft took off, Mr Glasgow said.
He said it was a "very rare situation" to apply wing anti-ice, with himself only having to do so six times in his 39-year career, but if a pilot did not apply it in those conditions he was not sure when they would.
Defence lawyer Matthew Muir said two witnesses and experienced pilots would give evidence that they did not believe wing anti-ice would have needed to be applied before takeoff.
They would also give evidence that the Boeing 737 had a low susceptibility to wing ice and it was "exceptionally unlikely, almost hypothetical" that it would be needed and if it was, an application of de-icing could have been made taking one minute.
Mr Glasgow said that based on accidents and serious incidents around the world even 30 seconds of ice can cause problems and de-icing "eats into the performance of aircraft" as it needed to heat the wing to remove the ice.
The aircraft was also no less susceptible than any other, Mr Glasgow said.
He said he was surprised at the different stance of the other pilots.