Air New Zealand says it is investigating an engine fault that led to an emergency landing Melbourne on Thursday.
Flight NZ726 from Melbourne to Auckland, with 145 passengers and six crew on board, developed a fault in one engine shortly after takeoff.
The A320 Airbus returned to Melbourne just before 8pm (local time) and landed without incident. Fire trucks met the plane on the tarmac.
The airline said on Friday morning that the first of the passengers had started embarking on flights back to New Zealand and it was likely to take the whole day for all of them to return.
Air New Zealand said engineers are investigating the nature of the fault and that reports of a fuel leak were incorrect.
Passenger Tobias Hague told the ABC he heard a bang, before one wing dipped and the aircraft began to descend, but the crew did not tell passengers what was happening.
"We were waiting for an announcement, waiting for someone to get on the little buzzer, and tell us what was going on, but it just didn't happen."
New Zealand comedian Jeremy Elwood was on the flight and said immediately after the plane landed, the captain explained the crew had been busy dealing with a problem with one of the engines and apologised for not talking to passengers sooner.
Mr Elwood told Radio New Zealand's Summer Report programme on Friday that passengers were calm and the landing was standard.
"When we were on the ground ... we could see the fire trucks, the airport rescue service, had been called out, so they were all waiting. I guess that was the first moment you went, 'oh ok, someone at least is taking this seriously'."
The ABC's Dan Conifer spoke to people from the flight and said they told him the lack of information during the flight made them anxious.
Passengers were been accommodated in hotels in Melbourne overnight on Thursday.