Passenger tells of loud 'smash' as lightning strikes plane engine outside window

A passenger on a plane struck by lightning has described the moment the bolt hit one of the engines as being like a car driving into a power pole.

"It was that loud - a real smash ... just this huge bang and lightning flicked past the cabin," Don Martin told the Herald.

Air NZ flight 615 was en route from Auckland to Queenstown this morning when the lightning struck during take-off about 9.30am.

"The plane was halfway up its ascent and suddenly did a quick, quite sharp turn to the left, and following that there was lightning and it hit the plane like you'd hit a power pole," the 73-year-old said.

"It really whacked the plane, beside us. It hit the top of the engine on the right-hand wing, so it was pretty exciting stuff."

The plane, understood to be an A320 airbus, kept going on a straight course out to sea before the pilot continued towards Queenstown.

"About half an hour later the pilot tells us that he wants to land and have it checked."

The aircraft diverted to Christchurch where Air New Zealand said engineers were this morning assessing any damage.

Martin, wife Lynne, 68, their son Paul and his wife Emily, and their three grandchildren aged 7, 5 and 1, were some of the 141 passengers and crew on board the flight.

He said he had flown a lot previously but never encountered a lightning strike and he had a bird's-eye view of the incident from his window seat overlooking the wing.

A screengrab of the Flight Radar website shows the 9.30am flight from Auckland to Queenstown diverted to Christchurch Airport. Photo / Flight Radar

Thunderstorms were passing over Auckland at the time of the incident.

Martin said the pilot warned passengers it might be a bit "lumpy" getting off the ground.

"I don't know why he turned. Maybe he saw it coming and thought 'I'm getting out of this'. I thought 'Gee he's turning early'."

After the bolt struck, Martin noticed a dent on top of the engine cover and said he didn't know if it was already there but noted: "The next plane didn't have one."

He thought the pilot might turn back but there were no other strikes and passengers remained calm thanks to a reassuring crew.

"They did a good job."

Once on the ground in Christchurch, passengers embarked almost immediately onto a waiting flight and Martin said they were only delayed by about an hour getting to Queenstown.

The family were heading to Wanaka for a holiday. He said the incident would give his two granddaughters something to talk about for school news.

Despite the otherwise uneventful flight, he was relieved to touch down in Queenstown.

"I'm good now I'm on the ground."