Captain Hughes pointed out the pilot operated under insufficient lighting and conditions of near darkness.
"That is why the restriction is in place. It does get dark early in Queenstown compared with other places without that terrain.
"The pilot also has the option of not departing.
"It is absolutely critical that we have that certainty and we don't depart on guess work."
Captain Hughes said airline pilots should obey procedures and, at the time the Pacific Blue flight took off, conditions for alternative manoeuvres in case of emergency were not met.
"It's not just me saying procedures are important ... they shouldn't be dismissed off-hand."
The pilot's common sense and experience did not give him the permission to disregard these procedures, he said.
"A reasonable pilot does not disregard the control tower weather report.
"They had provided a report and [the pilot] must abide by it."
A pilot can exercise his own judgement, he said, but when taking a more conservative approach.
The defence says the aircraft's lighter than normal weight of 59 tonnes meant it would be able to reach the required altitude even if one engine failed.
A return to Queenstown had been ruled out due to fading light.
Mr Hughes, under cross-examination, said he regarded the pilot's use of a Boeing chart to calculate the plane's turning performance in case of an engine failure as "flawed decision-making".
"The chart is not being used for the purpose it's intended. You could infer from this chart and refer backwards, but that's not what it's designed for."
Defence counsel Matthew Muir argued that decisions made by the pilot were based on "sensible and reliable conservatisms".
The case is expected to take a further two weeks.
