Hundreds of holidaymakers are being forced to cancel, postpone or reshuffle travel plans amid warnings that the eruption from the Icelandic volcano is strengthening and sending more ash towards Britain.
At least 5000 New Zealanders are due to fly to Europe this week, but their plans are in limbo as much of European airspace remains closed.
A glimmer of hope came early this morning (NZT) as Icelandic officials reported that the plume of ash wreaking havoc for air traffic across Europe was diminishing.
Gudrun Nina Petersen of the Icelandic Meteorological Office said the volcano was clearly spewing less ash.
"There is less ash. It's getting easier for Europe," she said.
Some airports began limited flights yesterday, sparking some optimism, but that received a setback last night as the British National Air Traffic Service said a new ash cloud was spreading towards Britain.
However, Ms Petersen said this was from earlier eruptions, and did not indicate a resurgence in volcanic activity.
House of Travel spokesman Brent Thomas said that of about 3000 New Zealanders due to fly out 10 per cent had cancelled their trips. Others had postponed while others were trying to take different routes to Europe.
Flight Centre, which has about 2000 people booked to fly to Europe in the coming days, said yesterday its official advice to passengers now was to cancel unless travel was absolutely essential.
Spokeswoman Marie Pilkington also warned against flying to a gateway destination such as Dubai, Singapore, Los Angeles or Hong Kong in the hope of getting a connecting flight.
Accommodation was scarce, and an unknown number of New Zealanders were already stranded there.
"It's quite a risk ... because the chance of getting through the gateways is quite slim."
Insurance booked through Flight Centre would cover any changes to plans, Ms Pilkington said.
UK and Europe airspace restrictions were to remain until at least midnight last night as the chaos which has stranded an estimated eight million around the world continues.
About 2000 visitors to New Zealand are stranded here.
A delegation of veterans, students and Defence Force personnel going to Gallipoli for Anzac Day has been delayed in Penang.
The party was due to reach Dubai yesterday but Wing Commander Brett Marshall said clearance to enter United Arab Emirates airspace had not come through in time.
He said clearance was requested last month, and it was not known why it had not been approved in time.
An increase in air traffic through the area because of the ash clouds over Europe was a possible factor.
Air New Zealand warned yesterday that the situation was highly changeable. A flight to London via Los Angeles left yesterday but was expected to go no further than the US.
European Union transport ministers have divided northern European skies into three areas: a "no-fly" zone immediately over the ash cloud, a caution zone "with some contamination" where planes can fly subject to engine checks for damage and an open-skies zone.
Qantas said yesterday its flights to London and Frankfurt would remain grounded as it sought clarification of the zones.
"At this stage it's very unclear about what airspace will be open and what will be safe to fly," a Qantas spokeswoman said
The travel chaos is affecting the New Zealand economy.
Aviation Industry Association of New Zealand chief executive Irene King estimates the country could be losing $1.5 million to $2 million a day from the disruption, with the national carrier bearing the brunt of the cost.
Air New Zealand said yesterday it had estimated the net cost of flight disruptions to its business at half a million dollars a day.
Meanwhile, some European airlines are angry over what they see as an overreaction. Test flights by KLM, Lufthansa and British Airways suggested planes could fly safely despite the ash.
"The analysis we have done so far, alongside that from other airlines' trial flights, provides fresh evidence that the current blanket restrictions on airspace are unnecessary," said British Airways chief executive Willie Walsh.
* Up to seven international comedians in this year's International Comedy Festival may be unable to get here.
Organisers are looking at possible replacements from a group of international comedians stranded in Australia.
- ADDITIONAL REPORTING: SUSIE NORDQVIST, AGENCIES