The two-pilot crew of an Airbus 320 were below the minimum safe altitude for two minutes on the morning flight from Auckland to Queenstown in July 2012, the Australian Transport Safety Bureau says.
The aircraft dropped to 1920 metres when it should have been flying at 2225m.
The bureau’s investigation found pilots failed to put it in the correct mode for landing – and only noticed when the first officer felt the plane was “going too fast”.
The investigation found they had intended to change the plane into the correct landing mode, but forgot.
A collision was highly unlikely given the fine and clear conditions, the report said.
The report said the situation showed how memory could fail, and the potentially serious effects of pilots being distracted.
The bureau found Jetstar’s procedures failed to draw the pilots’ attention to their mistake, and recommended extra guidance on landing and more warnings about the difficulty of the descent into Queenstown.
A Jetstar spokesman said the airline had conducted its own review, and had made changes including emphasising in crew manuals the importance of situational awareness.
Charts for Queenstown had been amended to emphasise the special requirements for flying into the airport, the spokesman said.
“Jetstar takes anything that happens in its cockpits very seriously,” the spokesman said.
“The aircraft continued to fly a safe approach and landing in clear conditions on the day of this event.”
The two pilots are still flying with Jetstar, he said.
They had over 23,000 hours flying experience between them, and had both flown into Queenstown regularly over the past three years.
Only specially qualified pilots are allowed to fly into Queenstown and the captain and first officer were considered qualified.