By Gyles Beckford
WELLINGTON (Reuters) - A cloud of ash from an erupting volcano in Chile disrupted air travel in New Zealand and Australia for a second day on Monday, causing scores of flights to be canceled and grounding thousands of travellers.
Flights between New Zealand and Australia, and some domestic routes in both countries, were disrupted as the cloud, which has travelled around 10,000 km (6,000 miles) across the Atlantic and Indian oceans, drifted over their southern air space.
Air New Zealand kept in the air by rerouting flights and flying at lower altitudes to avoid the ash, but was monitoring developments closely.
"We may well be affected later on today and tomorrow because if we can't exit or operate across the Tasman (Sea) and get to 20,000 feet before we enter into controlled air space then we will have issues in the next few days," said Air NZ chief pilot David Morgan.
Air NZ flights have been operating at around 18,000 feet although it is more costly in fuel consumption.
The volcano in the Puyehue-Cordon Caulle chain in Chile has been erupting for the past week, throwing South American air travel into chaos as it spews ash high into the atmosphere.
Virgin Australia, which had canceled services on Sunday, said it was resuming flights.
"Overnight we have been monitoring closely the situation and we now believe that conditions are safe to operate," said Sean Donohue, Virgin Australia's executive operations manager.
However, Qantas and its budget offshoot, Jetstar, maintained a ban on flying out of the southern city of Melbourne and the southern island state of Tasmania until mid-afternoon local time at least.
All flights within and to and from New Zealand were also still suspended, and Qantas canceled three services to Argentina and the United States because of the ash cloud.
The national carrier said the outlook was unpredictable.
"It is really difficult to say because it's so hard to predict the behavior of the ash cloud. We can only look 12 hours ahead at the most and even then it is difficult to say with any certainty," said Qantas spokesman Tom Woodward.
Despite the disruptions, airports in both countries reported little chaos at terminals On Monday, with many affected passengers having abandoned their travel plans for now.
New Zealand's Civil Aviation Authority (CAA) said there was no need for an official ban on flights and airlines would be left to make their own decisions.
"At the moment the ash is basically trapped in the stratosphere, it's not falling below that, so the air space below the ash cloud is viable for operations," CAA meteorological manager Peter Lechner said on Radio New Zealand, adding the effects of the volcano could last for weeks.
The fine ash particles, which pose a danger to aircraft bodies and engines, were carried east by the prevailing winds to sit between 20,000 and 35,000 feet across southern parts of Australia and New Zealand.
Air travel in northern Europe and Britain was disrupted last month after Iceland's most active volcano at Grimsvotn sent a thick plume of ash and smoke as high as 25 km. This was worse than the Chilean fall-out because it spread ash throughout the air column, from ground level to the upper atmosphere.
(Additional reporting by Chris McCall)