Scotty Donaldson: Why Some Airlines Can and Can't Fly As Ash Clouds Cancel New Zealand Flights

Ash clouds from the Chilean Puyehue-Cordon Caulle volcano have caused disruptions to travellers in Australia and New Zealand. The crazy thing with this situation is that if you are lucky enough to be flying with Air New Zealand, then your flights are continuing as usual, while Qantas and JetStar have far stricter policies and are not flying. This has left passengers stranded for days, while others have flown home pretty much unaffected. It ends up that Air New Zealand can use technological assistance from Civil Aviation and the Metservice to avoid the ash cloud and cruise under it which has seen it use ten percent more fuel, but has seen it deliver 50,000 passengers to their destination while competitors have been grounded. I am glad I am flying Air New Zealand to Europe!

Qantas planes will be parked for a fifth day as the airline today cancelled all trans-Tasman flights until 2pm tomorrow.

Jetstar also cancelled domestic and trans-Tasman flights, as an ash cloud from the Chilean Puyehue-Cordon Caulle volcano continued to drift over New Zealand.

Qantas was monitoring the situation and Jetstar has cancelled domestic and trans-Tasman flights for the rest of the day, as the ash cloud continued to drift over New Zealand.

The airline will provide an update this evening on tomorrow's services and the scheduled departure of a Singapore to Auckland return flight due to depart tonight.

"The safety of our passengers and crew is Jetstar's number one priority," the company said in a statement.

"Jetstar will not be flying into airspace that remains affected by the ash cloud until we are confident that it is safe to do so."

Virgin Blue cancelled flights to and from Perth due to forecast ash cloud in the area.

But Air New Zealand continues to operate flights, and yesterday said it had carried more than 50,000 passengers since the cloud arrived in New Zealand airspace on Sunday.

Aviation Industry Association of New Zealand chief executive Irene King said neither Air New Zealand's decision to fly or Jetstar and Quantas' decision not to fly was wrong.

"Both companies are right." It comes down to the airlines' policy.

"Qantas and Jetstar have a less permissive policy. Their policy would appear to be pretty blanket. If there is ash in the sky they can't fly.

"I think that's what is confusing the public a lot. They think, 'how can both companies be right?' Well at the end of the day it comes down to what your [policy] says as to how you manage these sorts of issues."

Captain David Morgan, Air New Zealand general manager of airline operations and its chief pilot, said the national carrier was working closely with the MetService and Civil Aviation Authority to determine safe flight paths to avoid the ash.

"The authorities are providing excellent information about the ash, which is at high altitude and very predictable in its movement.

"By adjusting cruising altitudes of our aircraft we are able to continue to safely deliver customers to their destinations.

"Lower cruising altitudes mean we need to burn around 10 per cent more fuel than normal, but we don't believe that's a reason to stop flying when there are perfectly safe flight paths available below the level of the ash," he said.

Emirates, Virgin Blue, Singapore Airlines, Air Asia X, Air Pacific, Malaysia Airlines, Thai Airways, Cathay Pacific and Korean Air were all offering international services yesterday.

Weatherwatch's Philip Duncan expressed surprise some airlines were still not flying, since they could safely avoid the cloud.
"It does seem strange that one airline can fly and another can't."

Meanwhile, GNS vulcanologist Graham Leonard said New Zealand's volcanoes Ruapehu, Tongariro and Taranaki were all capable of producing eruptions with as much force as Chile's Puyehue-Cordon Caulle volcano.
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New Zealand volcanoes erupted more frequently because of the type they were, he said. "All likelihoods are that we will all see multiple eruptions in our lifetimes."

Ash fallout from a nearby volcano could, at less than one millimetre thick, irritate the lungs and eyes, and people should be prepared to wear dust masks and goggles after an eruption.

Dr Leonard said ash from Chile presented no health risks to New Zealanders. The only risks were to aviation.

New South Wales university senior adjunct lecturer and aircraft maintenance expert Peter Marosszeky said volcanic ash had "disastrous consequences" on aircraft that flew into such clouds.

Dry ash acted as a sandpaper-like abrasive on all exterior parts of an aircraft. "In addition, it will choke up the sensitive ports within the engines and block them, as well as melting in the turbine area and forming an undesirable coating not dissimilar to glass."

The ash would form a glass-like coating and destroy some aerodynamic characteristics, he said.