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Fog at Christchurch airport and a small plane flipping on the runway at Wellington this morning caused disruption to a large number of flights and hundreds of passengers around the country.
An Air New Zealand spokeswoman said the incidents caused a knock-on effect throughout the network, so it was a busy day for airline's operations team.
The pilot and passenger of a small plane had a lucky escape when the Cessna 172 flipped onto its roof at Wellington about 10.30am.
Neither was hurt in the incident, possibly caused by a freak wind gust.
The airport runway was blocked by the plane and remained closed until about 1pm.
The Cessna was operated by the Kaikoura-based whale-watching operation Wings over Whales.
The company's director Andrew Crawford said the incident was a shock, but he was just relieved no one was hurt.
"It's just material damage, that's the main thing," he said.
A Wellington airport spokeswoman said there had been 24 scheduled flights into Wellington and 24 departures affected by the incident.
She said one international flight had been held at Sydney for an hour because Wellington was closed.
The Air New Zealand spokeswoman said it was difficult to get specific numbers of passengers affected by the problems.
"The majority of our flights into and out of Wellington are slightly delayed due to two sets of circumstances which are beyond our control - the fog in Christchurch this morning and the aircraft incident in Wellington."
On average, she said, the delays were about 30 minutes.
"We have had several cancellations and one Christchurch to Wellington flight was diverted to Palmerston North," she said.
"We're doing our best to minimise delays, and apologise to customers."
Witnesses said both occupants had walked out of the Cessna after it flipped at the southern end of Wellington's runway.
As a precaution, the CAA fire crew sprayed foam on the plane, but there was no suggestion of fire, Inspector Chris Tate, of police central communications, said.
A CAA inspector examined the aircraft.
Mr Crawford said he understood the plane was taxi-ing to takeoff just before 10.30am.
It was unclear exactly what happened next.
"Apparently it was getting a bit gusty, and maybe it was a freak gust or something.
"It's not quite clear yet, so we'll wait for CAA to investigate and then let's make sure it doesn't happen again."
- NZPA
