An Air New Zealand flight from Auckland to Wellington was diverted to Christchurch this morning.
Flight-tracking website Flight Radar 24 showed flight NZ405 circled over the Cook Strait before heading south to Christchurch.
"NZ405 from Auckland to Wellington diverted to Christchurch this morning due to a hydraulic system issue," an airline spokesperson told RNZ.
"This meant the aircraft required a longer runway for landing. The safety of our people and our customers is our number one priority. Impacted customers will be re-accommodated on the next available service."
A passenger on board the flight, James Camons, told RNZ the pilot tried to land in the capital twice before telling passengers he had to head to Christchurch.
"It was a little bit scary. I think most of the passengers were quite anxious after the second attempt failed, and the pilot said you know what, we can't land this thing."
Emergency crews checked the plane at Christchurch Airport before passengers disembarked, Camons said.
"Thankfully we landed safely in Christchurch, I'm very happy about that," he said.
But he was not happy about a five hour wait before the next flight the airline put him on, he said.
Camons was meant to land in Wellington at 8.30am, and now will not arrive until 3pm, meaning he would miss meetings he travelled for.
"We've got a lot of disgruntled passengers," he said.
"It's an absolute joke how they've dealt with this."
Air New Zealand said it put people on the next available flight.