The Civil Aviation Authority has confirmed a Pacific Blue flight out of Queenstown with 71 people onboard breached rules about flying after dark.
New Zealand's Civil Aviation Authority launched an investigation after claims that the Boeing 737 took off from the resort town in the South Island on 22 June this year outside the daylight hours of operation rules, contravening visual flight rules.
The Authority is also investigating whether low cloud and strong winds on the day in June should have stopped the plane taking off anyway.
There are no runway lights at the airport, or radar, so pilots have to operate on visual flight rules and be clear of the airport half an hour before twilight.
CAA director Steve Douglas says the flight did break the rules for the airport.
He says the plane did take off 12 or 15 minutes later than the departure time allowed from Queenstown.
Mr Douglas says the rules are important because of the often-gloomy conditions at twilight and Queenstown's mountainous terrain.
Witnesses see low flying jet
Witnesses described seeing the jet flying low to avoid cloud cover and in darkness as it tried to navigate its way through mountainous terrain.
Marty Black says the plane never climbed as it should, but instead flew at under 1000 feet as it tried to negotiate its way through the mountains in thick cloud and he thought it was going to crash.
Prime Minister John Key says the reputation of New Zealand's tourism industry relies on commercial aviation adhering to the strictest standards and the reports are concerning.
"It's vitally important for New Zealand's reputation and image that the high standard of air safety is maintained in New Zealand on commercial flights and we'll be wanting to get answers on some fairly obvious questions," he says.
Airways New Zealand, the organisation responsible for managing the country's airspace, says it was outside its jurisdiction to prevent the pilots from taking off and says the onus was on them to follow procedure.
Pilots stood down
Pacific Blue chief executive Mark Pitt says the airline stood down the pilots a few days after incident and it is taking the matter extremely seriously.
However, he called on the Queenstown Airport Corporation to address the shortcomings of the aerodrome.
Queenstown Airport chief executive Steve Sanderson says Airways New Zealand is consulting on the installation of runway lights and they should be in place later in the year.
Pacific Blue is a New Zealand subsidiary of Australian company Virgin Blue, which is owned by Sir Richard Branson's Virgin Group.