A ban on international air travel was lifted today and Air New Zealand said its flights to Europe would resume tonight with two flights to London, one at 9.30pm and one at 11.15pm.
The airline said within 24 hours there would be seven flights to and from London to begin clearing the backlog of thousands of passengers waiting in the two countries.
Air New Zealand said if there were no more airspace restrictions, it would return to normal services tomorrow.
It was looking at how it could provide extra seats to help with the backlog.
It said passengers who had been stranded in Hong Kong and Los Angeles on their way to London last week would get first priority, followed those with existing bookings on scheduled services, then passengers whose flights had been cancelled.
However, the airline also warned conditions were still very changeable and services could be delayed or disrupted at any time.
Several thousands passengers heading to Europe had been stranded in New Zealand after flights were grounded last Thursday by ash spewing from a volcano in Iceland, meaning aircraft could not fly because of the risk of the ash shutting down jet engines.
Britain's National Air Traffic Service (Nats) said today it was delighted to report most restrictions on its airspace began to be lifted today.
It said air traffic control services had resumed in the United Kingdom, apart from an area over northwest Scotland.
However, Nats said although the situation continued to be dynamic because of changing weather conditions and the prediction of dense areas of volcanic ash, today's announcement ended the disruption and uncertainty for air passengers.
Cathay Pacific said today planning for a recovery from the crisis was extremely difficult and appealed to passengers and the public for patience.
It said as services resumed, airlines would be competing for landing slots at airports, and airspace and airports would be "horribly congested".
The backlog would take time to clear and the airline appealed to passengers reserved on flights to Europe for non-essential travel to give them up, to free up seats.
The airline said it had about 1200 passengers in hotels and urged passengers flying to destinations outside Europe to consider returning home to wait for the situation to become clearer.
To help clear the backlog, Cathay Pacific said it would not take new bookings on flights to Europe before May 10.
It said the crisis had cost airline more than $US200 million ($NZ277.3m) a day in lost revenue and the cost to the industry was $US2 billion.
In New Zealand, Cathay Pacific passengers were advised to check the airline before leaving for the airport.
