Air New Zealand was last night forced to start cancelling flights because of volcanic ash from Chile – and the flight plans of thousands of passengers today are uncertain.

Five Air New Zealand flights in and out of Dunedin and six others operated by its subsidiary carriers Mount Cook and Air Nelson were grounded because of low-altitude ash from the Puyehue-Cordon Caulle volcano over the southern South Island.

Air New Zealand was also scrambling to get North Island-bound passengers out of Christchurch late last night, as the ash cloud moved north.

The travel plans of thousands of others around the country today are uncertain. Air New Zealand is to decide this morning whether to cancel more flights.

WeatherWatch.co.nz chief analyst Philip Duncan said the ash cloud moved over Dunedin early last night and would reach the edge of Christchurch early today.

It would remain over the South Island’s east coast until midday tomorrow. It would also reach the southern Wairarapa coastline, but “it won’t hit Wellington”.

The ash cloud in the southern South Island was particularly low, at just over 3000m.

Other airlines, including Jetstar and Qantas, have grounded flights because of the ash, but Air New Zealand had until last night been continuing to fly transtasman and domestic routes at a lower altitude to avoid it.

The airline had been flying below the ash cloud – which had previously been at a ceiling of about 8200m – increasing fuel consumption by 10 per cent.

Last night, it said increased ash activity in the south of the South Island had forced the cancellation of flights to Dunedin from Auckland, Wellington and Christchurch.

Spokeswoman Marie Hosking said Air New Zealand could not say whether further flights would be cancelled today.

“It’s impossible to predict at this point what the situation will be in the morning,” she said.

Ms Hosking said one Dunedin-bound flight returned to Christchurch Airport shortly after take-off because of the ash.

Otago University student Jimmy Tait-Jamieson, 20, was sitting in a Wellington-bound plane at Dunedin when the aircraft was grounded.

“The pilot said another flight needed to be arranged, but then we were told that Air New Zealand had cancelled all flights,” he said.

“The pilots were talking to Christchurch about whether they could fly lower and go under the cloud.

“We were about to leave when they told us we couldn’t take off,” Mr Tait-Jamieson said.

Chelsea Ngatuere was at Dunedin Airport about to return home to Whangarei after a visit to see family when her flight was cancelled.

She was worried that the disruption would unsettle her 13-month-old son, Josiah Ngatuere-Waaka, who lay in a carry-cot as his mother took care of the luggage.

Another passenger who left Christchurch on a flight to Auckland last night said Air New Zealand hurried other flights travelling north so they were not also cancelled.

“There was a flight earlier and they said in the PA announcement, ‘We really need this flight to get away on time because of the ash so please board immediately’.”

The MetService and the National Institute for Water and Atmospheric Research referred inquiries for comment to each other and the Civil Aviation Authority.

Air New Zealand said earlier yesterday that it had operated about 1000 flights and carried more than 50,000 passengers since the ash arrived in New Zealand airspace on Sunday.

Virgin Blue, Emirates, Singapore Airlines, Air Asia X, Air Pacific, Malaysia Airlines, Thai Airways, Cathay Pacific, Korean Air and others have also been flying to and from New Zealand.

Meanwhile, Qantas and Jetstar passengers will have to wait until at least today before their flights are cleared to take off.

More than 70,000 passengers in Australia and New Zealand have been at least temporarily stranded since the weekend.

Jetstar said it would not fly in airspace affected by the ash cloud until it was confident it was safe to do so.

In Australia, Qantas, Jetstar and Virgin Australia suspended more than 50 flights into and out of Perth yesterday, Associated Press reported.

Qantas was today expected to resume flights in and out of Tasmania, where some passengers have been stranded for four days.

GROUNDED

• NZ693 – Christchurch-Dunedin
• NZ694 – Dunedin-Christchurch
• NZ679 – Auckland-Dunedin
• NZ459 – Wellington-Dunedin
• NZ678 – Dunedin-Auckland
• * Mount Cook and Air Nelson (Air New Zealand subsidiaries):
• NZ8075 – Wellington-Invercargill
• NZ8077 – Christchurch-Invercargill
• NZ8069 – Christchurch-Invercargill
• NZ5320 – Dunedin to Wellington
• NZ5015 – Wellington to Dunedin
• NZ5361 – Wellington-Christchurch

– NZHerald, NZPA, WeatherWatch.co.nz