Air New Zealand crew are concerned about having to keep a "closer eye" on frisky passengers who might feel the urge to take advantage of the new Skycouch seats.
The lie-down seats - dubbed "cuddle class" - will allow economy passengers on the new Boeing 777-300 jets to recline along three seats, which are purchased together.
Some crew members are worried about PDAs (public displays of affection) and having to separate couples cuddling too closely as they seek membership of the 'Mile High Club'.
Crew fear Air NZ's world-leading new seats and medal-winning wine list may push some couples over the edge.
One Air New Zealand international crew member said hosts and hostesses may have to keep a close watch on couples sleeping together in the new seats.
"Hopefully it will remain a family show," said the source. "In terms of PDAs and mile highs it's nothing new.
"Will it increase people's urges? ... We will probably have to keep a closer eye on things."
She admitted there were already couples cuddling up together in the discreet boxed seats of business class. "You sometimes get people in business sleeping together."
A poll of cabin crew conducted by their union, the Flight Attendants and Related Services Association (FARSA), is understood to have revealed concerns about having to intervene in amorous couplings.
And sexologist Dr Michelle Mars said she believes the new seats could promote more couples to have sex in the sky, as many find the notion of cavorting in public "quite erotic".
"Even if a couple doesn't have the intention of doing it on the plane, the conditions might make them want to try," said the former Massey University lecturer.
"The whole point of public sex is that you don't get caught. The thrill of it for a lot of people is to be quiet."
FARSA would not elaborate on any concerns saying it was "too early in the piece" to comment.
Television presenter and league legend Matthew Ridge sparked complaints to cabin crew when he was caught getting steamy in business class with his then girlfriend, Rebecca Loos.
Notorious for her alleged affair with English football star David Beckham, Loos was flying Air NZ with Ridge from London to Los Angeles.
Other passengers reportedly complained about their mid-flight antics, forcing crew member to tell them to "modify their behaviour".
One passenger told News of the World afterwards:
"It was pretty obvious what was going on. They started snogging and then she disappeared under the blanket. I was shocked - it was then the steward told them to knock it off."
An Air New Zealand spokeswoman said: "Air New Zealand cabin crew are trained to deal with all issues onboard the aircraft, including amorous couples."