As she settled into the unfamiliar spot, a flight attendant asked over the intercom if she was on board.
Thinking she must have left something in the Koru Club, Campbell raised her hand.
The attendant said the aircraft door was closing, but someone needed to see her.
"I thought 'oh God, this is so embarrassing'," Campbell said.
"And then Maurice walked down the aisle and got down on one knee and proposed."
She had thought he was in Wellington getting his wisdom teeth removed.
"It was a complete shock," she said.
So shocked, the first thing she managed to utter was the "f" word.
"I'm known for my swearing, unfortunately. And then I said 'yes'.
Campbell said the experience was surreal - as Kent slipped an engagement ring onto her finger, the pilot came out and congratulated the engaged couple and the plane
erupted into applause.
A seat had been saved for Kent, and the pair flew home to Wellington side by side.
"It was just gorgeous."
When they landed, they were greeted by a spectacular water arch at Wellington Airport.
"And when we got off the air bridge, there was half of Koru Club waiting with bubbles and flowers - it was so overwhelming," Campbell said.
A lover of everything aviation, it made the proposal all the more wonderful for Campbell.
"Aeroplanes get into your blood. That's why it was even more special that he asked me on a plane."
The couple, in their 40s, don't plan on having children - but they do have a poodle-cross puppy called Harley, "a little bundle of blonde fluff", which Campbell said was more than enough work.