Up to 10,000 Jetstar and Qantas passengers were disrupted yesterday by the return of the same giant volcanic ash cloud that caused havoc for airlines last week.
And more trouble lies ahead today, as both airlines announced last night that they were cancelling domestic and international flights in New Zealand until at least noon.
Although the cloud, from a Chilean volcano, remained high enough for Air New Zealand and other airlines such as Cathay Pacific to choose to fly beneath it, the Civil Aviation Authority fears it may linger over the country for at least another two days.
"It's not moving to the east very quickly so I think we'll have at least a couple - maybe three - days of this," the authority's meteorological manager, Peter Lechner, said late yesterday.
"The ash cloud condition is not going to be any different tomorrow."
But Mr Lechner said the cloud, which is on its second circuit of the Southern Hemisphere and also disrupted flights around Australia on Tuesday, was high enough for airlines to operate safely beneath it.
"It's still quite navigable - it constrains their operations and means they have to fly lower, costing more in fuel and probably a bit more in terms of navigation, but it's a perfectly reasonable decision to fly below the cloud."
Air New Zealand estimates it needs to burn about 10 per cent more fuel than normal to keep flying, although it says it is keeping a constant watch on conditions and will not put its aircraft through volcanic ash.
Mr Lechner said that unlike a lower cloud which accompanied it last week and which was also spewed out of the Puyehue-Cordon Caulle, the unwelcome return visitor appeared to be trapped by the atmosphere at about 6100 metres above sea level.
Qantas resumed operations yesterday afternoon from Sydney, Melbourne and Canberra. However, both it and Jetstar decided to cancel all flights in New Zealand airspace.
Jetstar cancelled 28 domestic flights and 10 across the Tasman and Qantas, its parent airline, grounded about 26 transtasman flights.
Although Jetstar said it put extra staff on duty at its call centre to deal with an avalanche of inquiries, Aucklander Katherine Binning said she was put on hold for 86 minutes yesterday morning while trying to make alternative arrangements for travel to Melbourne.
She said that after she finally got through, an airline representative who was unable to advise whether extra flights would eventually be provided hung up on her.
"He said hang on a minute and the next minute he cut me off - I was so enraged."
Mrs Binning said she received no notice from the airline that her flight yesterday morning was to be cancelled, and she had to make two calls to Jetstar on Tuesday night before that information was confirmed.
She has been offered a flight on Saturday, but will have to return on Wednesday morning, cutting a day out of time she was planning to spend visiting her daughter in Melbourne.
She said a call centre member told her on Tuesday night that if she wanted to spend an extra day in Australia, she would have to pay more money, which she believed was grossly unfair.
A Jetstar spokesman said the airline was doing what it could to accommodate the wishes of as many people as possible.