Qantas and Jetstar have cancelled their New Zealand domestic and trans-Tasman flights for the remainder of the day as a result of the ash cloud from a Chilean volcano, which is expected to completely cover the country by this evening.
Air New Zealand will continue flying today but said its decision to go around or under the ash cloud was constantly being reviewed.
Qantas and its budget subsidiary Jetstar will not fly for the rest of the day and were reviewing whether or not to resume flights tomorrow.
They are expected to put out a further update this evening.
The airlines have also cancelled flights to and from some Australian airports.
New Zealand Civil Aviation Authority (CAA) spokesman Bill Sommer said the ash cloud from Chile's Cordon Caulle volcano had made a full circuit of the world and arrived back in New Zealand.
It was expected to completely cover the country by this evening, he said.
"I think the upper winds that are driving the ash cloud at the moment have become a little bit stagnant so, while it's hard to predict, I understand it may be with us for the next two or three days."
CAA manager of meteorology Peter Lechner earlier said it would be at 7300 metres (24,000ft) allowing plenty of air space for airline operations underneath.
It was up to individual airlines whether to fly, he said.
