Skiplagging is a sneaky travel hack that's been used by savvy consumers for years.
Instead of booking a direct flight to a desired location, customers in America are purchasing multi-stop fares with a stopover in the place they intend to go, forgoing the final leg of their journey.
The practice goes by a few different names, including skiplagging or hidden-city flying. Passengers disembark at their layover city, leaving an empty seat on their next flight, and save money in the process.
But airlines are cracking down on the practice, claiming it breaches their rules and costs them revenue.
Last week, American Airlines filed a lawsuit against a controversial ticketing website that allows customers to skiplag.
It comes after the airline barred a teenager from boarding a flight in the US after airport staff discovered he was planning to disembark at his stopover city.
Businesses argue the practice amounts to fraud because customers are purchasing flights they don't intend to travel on, while skiplaggers believe they are simply exploiting a loophole in ticket pricing.
The skiplagging travel hack
Skiplagging is buying a ticket to a destination with the intention of never completing the full journey.
It works like this: Say, for example, you're planning to fly from New York to Los Angeles, but the airfare is expensive. So, instead, you buy a ticket from New York to San Diego with a layover in Los Angeles, which is cheaper than the direct flight.
When it comes time to make your journey, you disembark at the stopover in Los Angeles and skip the next flight.
While the name has changed over the years, the idea has been around for a long time, says Robert Mann, an aviation analyst and a former airline executive.
"It really dates back to the era when airlines issued you paper tickets with red ink on them," he said.
The hack is not illegal, but it does violate a carrier's terms and conditions — that small box people tend to tick on autopilot when they purchase a flight.
Airlines are cracking down as fares skyrocket
Last month, skiplagging attracted attention online after a teenager was taken in by security at a US airport over concerns he was planning to disembark at his stopover city.
Seventeen-year-old Hunter Parsons was about to board his first flight alone, from Gainesville, Florida to New York City with a layover in Charlotte.
The plan was for the teen to get off the plane in Charlotte where he lives, his father told local television station Queen City News, but before he could board his flight, he was stopped by gate agents and taken to a room.
When questioned, the young man revealed he had been intending to skiplag in Charlotte and had his flight cancelled. The airline asked him to purchase a new direct flight, and banned him from flying with the carrier for three years.
Mr Mann is not familiar with the specific details of the incident, but says it is unusual for security to be involved in cases of skiplagging.
He says airlines have been cracking down on the practice in recent years, in part because they believe it is costing them revenue.
"Airfares have been high this summer, they were high last year, and the bigger the price — and the bigger the losses — the greater attention it gets [from airlines]," he said.
It is not clear how widespread skiplagging is in the US, though interest appears to have grown as websites facilitating the practice have spread online.
Opinions on the hack are mixed. There are analysts like Mr Mann who are firmly against it and believe it is immoral, while others argue the airlines have done this to themselves.
"Their pricing models are incredibly complex. It's not like when you go into a supermarket and a bottle of milk costs this price and it's the same price charged to every customer that goes in and buys that product that day," says Chris Chamberlin, a travel journalist at frequent-flyer tips site Point Hack.
"Every time you book a flight, the price can be different."
Airline pricing systems are determined by a range of variables, including competition, popularity and the type of route.
Mr Mann uses a "gravity model" to explain pricing between major hubs in America. If the cities are big and the demand is huge, then prices settle at a higher point because there is a higher amount of gravity between large objects.
Or to put it another way, most people prefer to avoid stopovers so there is more demand for a direct flight from point A to point C, pushing the price up.
Since there is less demand to fly from point A to point C via point B, the price point is lower.
Over the years, airlines have tried suing to claw back what they say are financial losses caused by skiplagging, either by targeting individuals or sites that facilitate the practice, but making their case in court has proven tricky.
The case of the airline giant and travel hacker
Tech entrepreneur Aktarer Zaman appears to have been one of the first to create a website devoted to finding hidden city flights
In 2014, the then 22-year-old started Skiplagged, an airfare search engine for cheap flights with layovers, while working at a tech startup, according to CNN.
The site is now one of the most recognisable brands in the space, a detail that has not escaped airlines' notice.
Last week, American Airlines accused the company of engaging in "unauthorised and deceptive ticketing practices" in a 37-page lawsuit lodged in Fort Worth, Texas.
It claims the website improperly acts as a middleman, "inserting itself between American [Airlines] and flight consumers", and promises to deliver savings, but often charges consumers more than if they had booked a ticket directly with the airline or an authorised agent.
"Skiplagged deceives the public into believing that, even though it has no authority to form and issue a contract on Americans' behalf, somehow it can still issue a completely valid ticket. It cannot. Every 'ticket' issued by Skiplagged is at risk of being invalidated," it said.
In a statement to the ABC, a Skiplagged representative said: "Skiplagged is proud to stand on the side of the traveller and continue the fight against American Airlines and their monopolistic pricing."
"The result of skiplagging is that travellers have been able to put extra money in their pockets instead of the pockets of American Airlines executives and shareholders," they said.
This is not the first time Skiplagged has been sued. In 2014, United Airlines and its travel partner, Orbitz, claimed Zaman's website created "unfair competition" and sued to recoup $US75,000 ($116,872) in lost revenue.
"This practice violates our fare rules and we are taking action to stop it to help protect the vast majority of customers who buy legitimate tickets," the airline said at the time.
Zamen used GoFundMe, asking for $US10,000 to help cover the cost of his court battle.
"I was not optimistic that I could take on the legal fight," Zaman told CNN in 2014.
But he raised $US81,000 and Orbitz eventually backed out of the suit after quietly settling with Zaman, while United Airlines had their case dismissed in a Chicago court.
The judge ruled he did not have jurisdiction because Zaman did not live or work in the city, according to CNN Money.
Southwest Airlines also sued the website in 2021, alleging it worked in concert with another travel company, Kiwi.com, to sell its flights without authorisation. But the case was dismissed by a judge after both parties reached an undisclosed settlement.
Mr Mann believes airlines have a legal case, but there is still a question of whether they can prove it in front of a judge.
"So far, judges just pull out their hair and say, 'Well, you know, we don't understand this, we don't really think anybody has any damages because, after all, they pay you something and so what if they didn't use it all?'"
Can you skiplag in Australia?
Mr Chamberlin says it's possible to find cheaper multi-stop flights in Australia, when compared to direct flights to busy hubs like Sydney or Melbourne.
There may be an opportunity to skiplag domestically or internationally, but it's unclear whether people are actually doing this and on what scale.
Customers would need to spend time researching and comparing different fares, flights and prices and complete their journeys undetected, analysts say.
And if they do skiplag, they run the risk of a last-minute change being made to their ticket, which may result in a different layover city being used or avoided altogether.
If airlines discover a person is skiplagging, they can cancel their flights, take away their points or ban them from flying with them.
Hidden city sites in the US offer guidance to passengers on how to avoid getting caught, including not linking frequent flyer points when booking and only using carry-on baggage, a possible deterrent to customers using Australian airlines, which tend to crack down on cabin bags, Mr Chamberlin says.
Mr Mann says there is also an ethical element to the travel hack, which should deter people from engaging in skiplagging.
"If you do it yourself, you're subject to all these potential clawbacks. But if you use a piece of software to do it, well, you're giving business to somebody whose business it is to defraud suppliers."
Others have also argued that by skiplagging you are taking away a seat from another passenger who needs it, but Mr Chamberlin says airlines often overbook flights.
"It's a very common practice in the aviation industry that airlines will always sell more tickets, if they can, than the seats that they have on the plane, because they know that a certain volume of passengers will not show up or between the time that they bought those flights and the time it comes to depart, they'll change or cancel their ticket," he said.
The best travel tips to save on your next flight
Mr Chamberlin says skiplagging isn't something he would personally recommend, but he says there are other ways people can save when they fly.
He says to make sure you book early, since prices are highest if you're booking last minute. It also pays to be flexible with your flight schedule, particularly around the time and day of the week.
"I always tend to find the flights first thing in the morning on weekdays, last thing in the morning on weekdays, [and anything] at the very beginning and very end of weekends to be the most expensive because that's where most leisure travellers want to fly," he said.
"So if you want to save money on tickets, it's probably easier to be flexible on your travel ... take a flight at lunchtime one day instead of trying to be in the office by 9:00am after landing. You can sometimes fly for half the price."