Ash flights resume in Australia, but NZ hit

SYDNEY: Australian flights grounded by the Chilean ash cloud resumed Wednesday as the plume cleared, but thousands of passengers endured lengthy delays as airlines scrambled to clear a huge backlog.

Hundreds of services were cancelled Tuesday in Sydney, Melbourne, Adelaide and Canberra but the threat of prolonged disruption eased as the ash from the Puyehue volcano eruption pushed out towards the Tasman Sea and New Zealand.

"The ash cloud affecting eastern Australia has cleared, and airlines are returning to normal operations Wednesday afternoon," said the Bureau of Meteorology.

But while mainland routes got back in the air, Qantas, Jetstar, and Virgin services to Tasmania and New Zealand were all halted until further notice as the ash moved south.

Qantas restored flights to and from the South Australian capital Adelaide before dawn, followed by Melbourne.

Canberra and Sydney routes were operating again by early afternoon, including international flights, although Qantas said delays were expected on overseas services into both Sydney and Melbourne.

Virgin also resumed flights from the major cities.

Despite planes being airborne, Qantas spokeswoman Olivia Wirth said thousands of customers had been affected once again.

The airline was putting on extra flights to work through the backlog of passengers, some of whom have been stranded for two days.

Despite other airlines taking a conservative approach, Air New Zealand has maintained most services by flying under the plume, and said its routes continued to operate as normal.

New Zealand Civil Aviation Authority meteorological manager Peter Lechner said the cloud was expected to cover the entire country later Wednesday and due to slow-moving winds would linger for "at least a day or two".

Ash poses a significant threat to aircraft because once sucked into engines it can be transformed into molten glass by the high temperatures and potentially cause an engine to fail. (AFP)