The authority investigating an Air NZ flight to Sydney which diverted to Auckland is looking into the engine type that's had issues overseas.
The Transport Accident Investigation Commission (TAIC) was investigating after the Airbus A320 issued a mayday but then safely landed in Auckland an hour after departing from Wellington.
TAIC chief investigator of accidents Naveen Kozhuppakalam told Morning Report they were aiming to identify any systemic issues that may have caused the engine malfunction.
It was still very early in the evidence gathering, he said.
The Airbus A320 was powered by Pratt & Whitney engine which been "facing issues" globally, Kozhuppakalam said.
"But it's just too early to say whether the engine malfunction was related to the issue.
"Our priority is to make sure that the travelling public is safe and the investigation will try and identify if there are issues that need to be addressed."
Air New Zealand had processes in place to make sure any Pratt & Whitney engines were safe to fly, he said.
"There is no reason for Commission to believe the aircraft or Air New Zealand is unsafe."
However it was classified as a "serious incident."
"Those are unusual circumstances and we want to understand why and how."
TAIC wanted to hear from passengers on the flight.
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