Pacific Blue airline captain's use of airport windsocks to measure wind gusts before taking off was both criticised and defended in the Queenstown District Court yesterday.
Retired Air New Zealand pilot and witness Colin Glasgow said this method was unreliable, as pilots were not trained in it because windsocks varied and did not measure velocity.
He was giving evidence in the prosecution of a 54-year-old Auckland pilot who faces charges of operating an aircraft carelessly. The pilot has interim name suppression.
While cross-examining Mr Glasgow, the pilot's lawyer, Matthew Muir, said the pilot had used the airport's windsocks to measure the gusts, which he and the first officer said had "reduced in severity".
"They [the pilot and co-pilot] will say they were observing the windsock at the crossway and it indicated somewhat less velocity than they were having reported from the tower."
Mr Glasgow, a pilot of 39 years' experience, said: "If you had a dozen pilots and asked them, you would end up with 12 different answers on which speed it was.""If Captain ... took off because he could see the wind gusts, then he is a lot more skilled than your average pilot.
"You can't see wind. You can only see the results of it. These were large gusts and they were unpredictable. You couldn't predict when they were coming through and they were certainly coming through on departure.
"From my view, they came to the wrong decision."
Mr Muir said the captain and first officer were satisfied with the amount of crosswind during their departure.
The Civil Aviation Authority alleges the defendant left the airport at 5.25pm on June 22, 2010, breaching the airline's rule that flights could only leave at least 30 minutes before the evening civil twilight time of 5.45pm.
Mr Glasgow disagreed with the decision-making and methods.
"I'm not sure what exactly was in the mind of Captain ... when he took off. All I am saying is, it didn't look good and I wouldn't have taken off."
Mr Muir said the pilot had "worked on the assumption there would be a broken layer" of cloud once in the air and past the Frankton Arm.
"He had observed very significant clearance and could see the Remarkables."
Mr Muir said the pilot had based his assessment on, and applied, "sensible conservatisms" before takeoff and in the air.
Mr Glasgow said he could not understand the thought processes of the pilot.
"I actually don't know what was going on in [the pilot's] mind.
"He is not free to create an ad-lib departure alternate. He doesn't have the expertise.
"I want to amplify that to assume you can turn and reconfigure the aeroplane ... I just don't know how that can be achieved. In reality, it didn't happen. The pilot had to descend to see ... we are working on assumptions."
He said winds exceeded the 16-knot crosswind limitation on several occasions before the plane's departure, at one occasion reaching 35 knots.
"On a wet runway, with virtually no friction, there is nothing a pilot can do about it.
"It doesn't matter how good the pilot is, the aircraft is going to lose grip and adherence."
The wind gusts that day were regular and significant, and the pilot could not have predicted when they would arrive or if they would be in the aircraft's pathway, he said.
The hearing, before Judge Kevin Phillips, enters its eighth day today. The accused pilot is yet to give evidence.
