Helicopters Otago pilot and chief executive Graeme Gale said he was "really furious" about the latest incident, which happened during a critical stage of flight around midnight on Tuesday.
A crew with a full medical team had been approaching Dunstan Hospital to pick up a patient who needed to be transported to Dunedin Hospital for care.
The helicopter had just descended from low clouds over Bridge Hill and was transitioning from flying by instruments to using night-vision goggles when the incident happened.
They were hit by a bright green laser, shone by "some idiot" in the centre of Alexandra, which lit up the whole aircraft, Mr Gale said.
The incident, which happened at a critical moment in flight, "could have been catastrophic", Mr Gale said. He was concerned someone would cause a serious accident if such behaviour continued.
Laser strikes could cause temporary blindness to the pilots and there were "plenty" of examples of people’s eyesight being permanently impaired by such incidents, he said.
"This is really serious stuff," Mr Gale said.
"We're not doing it for fun, we’re doing serious life-saving missions and we’re having clowns like this doing seriously endangering acts like that. It’s just mind boggling. It’s absolutely unforgivable," Mr Gale said.
He believed anyone shining lasers at aircraft should be given as long a sentence as possible.
"As far as I’m concerned, they should lock him up and throw the keys away," Mr Gale said of the person who had shone the light on Tuesday.
His staff had reported the incident to police, and Mr Gale encouraged anyone who witnessed such behaviour to do the same thing.
"If anyone ever sees anyone using a laser at night, pointing it towards an aircraft, they should immediately contact the police — that would be most useful," Mr Gale said.
In June, Michael Stirling (33), of Dunedin, was sentenced to nine months’ intensive supervision and 100 hours’ community work after shining a laser from South Dunedin at a rescue helicopter at 1.44am on December 2.
