"I was hunched over the patient delivering the baby from the side, which is not ideal."
The helicopter was above Bean Rock Lighthouse, off the coast of Mission Bay, when Charlie emerged at 9.42am.
The tiny baby was born more than three months before the due date of June 11.
"The baby came out very quickly with not much warning," Clarke said. "She was small enough to fit in my two hands."
Ngaire remained calm throughout the birth despite being uncomfortable, and focused on the regular contractions, he said.
"She sort of took it in her stride. She knew the baby was coming and it was inevitable the baby was coming.
"It was her sixth baby, so she was pretty used to giving birth, I suppose."
This was the first time Clarke had assisted a birth mid-flight, as patients usually gave birth either before or after the helicopter trip.
Charlie was in a stable condition in the hospital's intensive care unit last night, and Ngaire was in a hospital ward.
Ngaire's partner Bryan Livingstone said their daughter was "touch and go".
"She was just too early," Livingstone said. "But she's stable and she's in good hands.
"Once her condition is stabilised we will be giving the Westpac rescue people some flowers and seeing them again to give them a massive thank you," he said.
Ngaire's sister Billie said it was the second time Ngaire had been airlifted from Waiheke Island while in labour.
"Her last one was born at 27 weeks. She had him when she got to Auckland Hospital and now he's 20," she said.
"This baby is very prem. We've been told it's 50-50 at the moment. She's only 750g," she said.
Waikato Hospital neonatologist Dr Phil Weston said a 26 weeks gestation baby was fully formed but their organ functions would not be great.
He said babies born as early as 24 weeks were able to survive, but premature babies needed close hospital attention until the due date, when the baby would likely be able to breathe alone and suckle well enough to gain weight.
