Firefighters rushed to Auckland Airport this morning after a plane had to land shortly after take off as smoke came from the cockpit.
Passengers on the Mt Cook Airlines flight were evacuated on the taxiway at about 8.30am, according to a Fire communication spokeswoman.
Engineers were called in but were unable to find any signs of fire.
The spokeswoman said they had concluded what they thought was smoke was most likely steam from an air-conditioning unit.
Air New Zealand owns Mt Cook Airlines, and said the flight, bound for Palmerston North, had just taken off before grounding again when the smoke was detected.
There were 52 passengers on board at the time.
An Auckland Airport spokesman said police and ambulances had also been on hand as part of their emergency protocol.
There were some delays to other flights but he said they were minor.