As two Nova Scotians prepare to go to trial for allegedly committing a sexual act on an Air Canada flight, experts say joining the so-called Mile High Club is more common than one might expect.

Cynthia Sullivan, director of the Atlantic Flight Attendant Academy, said dealing with passenger promiscuity is part of the academy's curriculum.

"We discuss the Mile High Club. Often it comes up in a question, but we also have some articles and cite some situations that it can happen, because some people are not familiar with it," she said.

"It's important that they know about it before they just witness it."

Alicia Lander, 25, and Jason Chase, 39, have pleaded not guilty to charges of committing an indecent act. They were represented by their lawyers in Dartmouth provincial court on Tuesday when their trial was set for Jan. 21, 2015.

Lander was also charged with causing a disturbance, assaulting a police officer and mischief after she and Chase were arrested following an Air Canada flight from Toronto to Halifax in January. Her lawyer entered a plea of not guilty on those charges as well.

Sullivan said her students inevitably ask whether she's witnessed such an act.

"I have," said Sullivan. "It happens more often on longer flights, of course. The transatlantic flights are the most popular, but it happens in business class as frequently or even more so than economy class, for instance."

How common is it?

In the early 2000s, Transport Canada conducted investigations into an apparent increase in the number of unruly passengers, but the results did not contain specific information about sexual activity on airplanes.

Mark Gerchick, an aviation expert who recently wrote an article for The Atlantic called "A Brief History of the Mile High Club," said the best numbers come from travel companies such as Expedia.

In December, the online travel company surveyed 1,000 air travellers and found that nine per cent of them reported being intimate on a plane at least once.

Other surveys performed by private companies paint a picture of how common it is for people to join the Mile High Club.

"Condom makers have taken polls of this and when the question is phrased more in terms of, 'Have you had sex or have you had sexual activity on an airplane?' the numbers tend to be around three per cent," said Gerchick.

"The fantasy itself does seem to be pretty widespread. Again, public polls sort of indicate something like a third of passengers, I should say male passengers, harbour this, seem to put it on the bucket list."

Unsurprisingly, when there's demand, there usually is some business looking to step up and supply that demand.

Dave MacDonald runs an airline called Flamingo Air. The airline is actually just one plane — a 1969 single prop Cherokee Piper based in Cincinnati.

For $420, passengers get one hour of flight time in a private, curtained-off area of the aircraft.

"I've got to tell you, it's cute as the dickens," said MacDonald.

"We take out the whole centre row of seats, we put in big fluffy cushions and you get champagne and chocolates and souvenirs — and of course a very discreet pilot."

Why on a plane?

Over 20 years, MacDonald said he has taken thousands of couples on that flight.

"Aviation has always had that allure. It was always a specialty of adventure and freedom and I think it's probably one of the big contributors to that interest," said MacDonald.

Of course, there's not much freedom on a packed commercial airliner, but Sullivan believes that close proximity may also be part of what brings two people together — that and alcohol.

As for the potential legal repercussions of joining the club, that’s complicated.

According to the Criminal Code of Canada, such an act must be intended to "insult or offend" another person, meaning the act itself is not illegal. But Canadian aviation regulations also come in to play.

Regulations state that anyone who disobeys orders from the flight crew can be found in violation.

Sullivan said it's often best to turn a blind eye.

"Especially if it's a washroom and then you see someone else come out later, one person and then a little while later another — it's really probably too late to do anything," she said.