Snagging the best airfares can often feel like an endless treasure hunt, running around in circles adjusting flight times and number of stops to strike the right balance. One hack that has been rising in popularity is booking hidden city fares, also known as skiplagging, because of the tremendous savings it can yield. “The reason someone might try to utilize hidden-city ticketing is simple: People can fly directly to their destination without paying the direct flight price tag,” Going.com spokesperson Katy Nastro says. That means that passengers can save by booking a cheaper one-stop flight with a layover at their desired destination and then leave the airport there, abandoning the second leg of their booking. Though it may seem complicated to find those fares, the site Skiplagged has become a favorite for price-savvy travelers—and the payoff can be huge. Average Skiplagged savings on flights between San Francisco and Chicago are 55.08% less, Los Angeles and Atlanta 59.19%, Minneapolis and Detroit 63.91%, and Honolulu and Salt Lake City, 67.6%, according to Daniel Gellert, COO of Skiplagged. Cost savings like these prompted North Carolina resident Hunter Parsons to recently book a recent American Airlines flight for his teen son Logan to fly from Gainesville, Florida, to New York City with a layover in Charlotte, where he would get off. When a gate agent noticed the teen’s North Carolina ID, she questioned him—and unaware that the practice of skiplagging is technically against the airline’s conditions of carriage, the teen revealed his destination. The result: Parsons’ two-leg ticket was canceled, and the family had to buy a new ticket for a direct flight to Charlotte. While Parsons’ incident resulted in headlines claiming the teen was “detained,” an American Airlines spokesperson says, “Our records indicate the customer was questioned only at the ticket counter about their travel while attempting to check-in for their flight.” Recent crack downs like this by airlines have made the practice more controversial than ever. From the airlines’ point of view, empty seats can be problematic. “If a customer knowingly or unknowingly purchases a ticket and doesn’t fly all of the segments in their itinerary, it can lead to operational issues with checked bags and prevent other customers from booking a seat when they may have an urgent need to travel,” American Airlines says. “Intentionally creating an empty seat that could have been used by another customer or team member is an all-around bad outcome.” But Gellert said it’s less about operations and more about the monopoly that the airlines have on the market. “The reality is the airlines have written the rules upon which they can play,” he says. “They recognize how illogical the pricing is. And now we’re in this world where these things make no sense, like the traveling teenager who bought the ticket for the flight—doesn’t he have the right to use it or not use it?” Technically speaking, the practice isn’t breaking any federal laws, but it is violating the airlines’ policies, so flying hidden-city fares comes with an inherent risk. “Someone who flies once a year might try this tactic, but be unaware of the risks or nuances,” NerdWallet travel expert Sally French says. Those repercussions can come in a variety of forms. “Some airline terms and conditions state that passengers could be permanently banned from flying in the future with that airline, or that the airline might take legal action against the passenger,” she says.

While those cases might be extreme, the more likely scenario is a monetary penalty. ”If you’ve booked a roundtrip flight and you skipped on the second leg of your outbound flight, there’s a chance the airline could cancel your reservation for the return trip home,” French says. Other hiccups are more logistical. Skiplaggers can’t check luggage since they’re usually routed directly to the final destination on the ticket. Even those traveling with just a carry-on can run into issues. “You might be one of the unlucky ones who doesn’t snag overhead bin space, in which case flight attendants might force you to check your bags, upon which your bag will be shipped to a destination you never intended to go to,” she says. And what might be a wrinkle in an original flight plan could turn into being totally sidetracked, especially with last-minute schedule changes. “Say you booked a round-trip flight from San Francisco to Seoul, with a layover in Singapore where you intended to get off,” French says. “A schedule change could mean the airline might reroute you, and that layover in Singapore becomes a layover in a completely different city—meaning you never get to your intended destination.” The company Skiplagged is well aware of these issues, too (and offers airfares other than just these). If the offered fare does require skiplagging, the site will issue a number of alerts to make sure the passengers are well aware of what it involves—and make the decision they see fit for themselves. “Any actions taken by the airlines tend to be few and far between compared to the number of people that are doing it because they need this money in their pocket,” says Gellert. While the risks are out there, there may be times when it can make sense. “The practice is not illegal, and even was blessed by New York Times’ The Ethicist for the same reason that you have the right to buy a whole cake, but aren’t required to eat every slice,” Nastro says. “And while the practice can be a handy tool to use occasionally for finding cheaper flights, it is not for the novice traveler.”