A Sunwing Airlines jet from Halifax to the Dominican Republic was forced to make an unscheduled landing in Bermuda after passengers were allegedly smoking mid-flight, a costly incident for any airline that can easily incur tens of thousands of dollars in expenses.

Daryl McWilliams, vice-president of media relations with Sunwing, told CBC News that the airline plans to sue the family that was involved in Friday's incident, and added that costs are approaching $50,000.

That bill includes having to put up the passengers and seven crew members in a hotel overnight, and paying a different crew to search the plane for extinguished cigarettes because the alleged smokers refused to say what they did with them.

The airline also had to send a mechanic to inspect the plane because it had too much fuel onboard and landed overweight, triggering a requirement under Canadian transport regulations, McWilliams said.

The plane was scheduled to pick up passengers in the DR who also had to be put up in hotels overnight Friday.

A diverted flight can also generate plenty of headaches and costs for passengers who miss pre-booked events, business meetings or time with friends and family.

'[It] depends on size of the aircraft and number of passengers on board, severity and operational consequences.'—Perry Flint, International Air Transport Association

Australia's Qantas airline said it incurred $125,000 in expenses after a Sydney to Tokyo flight dumped nearly 60,000 litres of fuel before landing in northern Australia in December.

In that incident, a man allegedly lit a cigarette in the bathroom before punching and spitting at a crew member.

Perry Flint, from the International Air Transport Association (IATA), said there is no average cost for diversions. However, he said they typically range between $10,000 and $200,000.

"This depends on the size of the aircraft and number of passengers on board, severity and operational consequences: delays, passengers' resulting misconnections, flight cancellation and the cost of hotels/meals for passengers and crew," Flint, head of IATA’s corporate communications for the Americas, said in an email to CBC News.

Not all unscheduled landings prompted by unruly passengers, however, end up being so costly, Sunwing's McWilliams said.

Sometimes a plane will land, unruly passengers are taken off by authorities and the flight takes off again for its original destination.

Nor are these incidents necessarily a result of too much drinking at cruising altitude.

"I can tell you the most common reason for an unscheduled landing, by far, is a medical emergency," McWilliams said, adding that in such situations the airline never attempts to recoup expenses.

Those incidents are also quick, he said, because medical staff are usually already at the airport waiting to receive the passenger.

Decision rests with captain

The final decision on whether a flight will be diverted ultimately rests with the captain, Kelly James, spokeswoman for Transport Canada, said in an email.

According to the Canadian Aviation Regulations, operators must have procedures to deal with a range of unruly passengers from the "unacceptable use of language" to lewd behaviour, the use of weapons and attempts to enter the flight deck.

Only the least severe — minor incidents involving language — do not need to be reported to Transport Canada.

According to Kelly, there were 103 incidents recorded in Transport Canada's civil aviation daily occurrence reporting system over the last 12 months involving disruptive passengers.

The database contains the initial reports of incidents at Canadian airports, planes registered in Canada and those occurring in Canadian sovereign airspace.

It also includes incidents in foreign airspace for which Canada takes responsibility.

The reports cover the gamut of unruly behaviour, from intoxicated passengers — some who bring their own alcohol onboard — to smoking or refusing to turn off a cellphone. Some involve alleged assaults against passengers and crew.

The Gander International Airport in Newfoundland, which is located on the flight path for planes travelling between the U.S. and Europe, receives between 35 and 50 international diversions each year, according to Reg Wright, director of marketing for the airport.

However, only about 10 per cent involve unruly passengers. Medical emergencies account for about 48 per cent of the total, while mechanical issues account for 42 per cent.

"Where we do see incidents of unruly passengers, alcohol, drugs or mental illness are almost always contributing factors," Wright said.

Steep fines, jail time for flight disruptions

There is no shortage of high-profile incidents that generate a tremendous amount of media attention.

Two former executives with technology giant Research In Motion pleaded guilty to mischief and paid $71,757 in restitution after an Air Canada flight from Toronto to Beijing was diverted to Vancouver in December 2011.

Court documents suggest the pair were inebriated, yelled at each other, and one of them warned he would "off people when they left the plane." They were subsequently let go from RIM, now known as BlackBerry, for unprofessional behaviour.

The types of incidents can sometimes involve just crew members.

A JetBlue Airways flight from New York to Las Vegas was forced to make an emergency landing in Texas in March 2012 after its captain started running down the aisle and screaming incoherently about terrorists. He was charged with interference with a flight crew but was found not guilty by reason of insanity.

As far as penalties go, a person convicted of disruptive behaviour on an aircraft can be fined up to $100,000, sentenced up to five years in prison or both, Kelly said.

It is ultimately up to Crown prosecutors to determine whether charges are laid, she said.