How a Mistake Could Help You Save Hundreds on Flights

Sometimes, a flight deal seems too good to be true. For example, there might be $187 round-trip flights from the United States to far-flung cities like Casablanca, Johannesburg, or Beijing (Thrifty Traveler spotted these outrageously low fares in late August).

Or, more recently, Scott’s Cheap Flights noticed round-trip tickets to cities across Australia for as little as $509.

When airfare drops this low, it’s often labeled as a mistake fare, an error fare, or sometimes a “fat finger” fare. These names indicate what happens when a misplaced decimal point, miscalculated currency conversion, or data entry error accidentally publishes incorrect (and incredibly cheap) ticket prices.

Sometimes, mistake fares are the result of a ticket posted before airport taxes or fuel surcharges are added. Other times, they’re simply caused by a computer glitch.

Whatever the cause, error fares can result in truly outrageous flight prices, the likes of which wouldn’t happen during even the best airfare sale.

Where to Find Mistake Fares

Any site or app specializing in flight deals (we love the Airfare Spot, Scott’s Cheap Flights, The Flight Deal, and Thrifty Traveler) will spot mistake fares before the airline even notices that their $4,000 business class seat is selling for $400.

Why They’re Frowned Upon

In the past, airlines were required by the Department of Transportation to honor mistake fares, however under priced they were. The landmark United Denmark fares, however, set in motion the DOT’s decision to allow airlines to withdraw these tickets.

In February 2015, $51 first class flights from New York to Copenhagen were found on United’s Denmark website — but they could only be booked in Danish krone when travelers indicated Denmark in their billing address (even though most purchases weren’t made from Denmark-based individuals).

The DOT determined that there was “evidence of bad faith,” and that travelers had to intentionally “manipulate the search process…to force the conversion error.”

In situations such as this, booking mistake fares is largely frowned upon — not only by airlines and government organizations but also by people who, typically, book full-fare tickets.

Related: The Best New Ways to Book Your Flights

How to Book Them

Error fares can typically be booked through an airline’s website or an OTA (without even having to go to a foreign website or lie about your billing address).

Scott’s Cheap Flights recommends that when travelers suspect a deal is a mistake fare, they book directly through the airline whenever possible — and quickly, before the carrier figures out what’s up.

“It’s better to buy directly from the airline since the chances of it being issued and honored are much higher,” the site explained.

Tickets purchased directly through an airline are often issued much quicker, too, further increasing your chances of having the deal honored. Once your seat is ticketed, you’re pretty much in the clear.

Months after the Danish United fares were published — and retracted — the DOT ruled that, if an airline could prove fares were truly published by accident, they could rescind those tickets.

“The burden rests with the airline…to prove to the Enforcement Office that an advertised fare and the resulting ticket sales constitutes a mistaken fare situation,” the government department stated.

Airlines must, however, reimburse all out-of-pocket expenses made in confidence upon the reservation, according to USA Today. That means that travelers will not only be refunded for the cost of the ticket, but they can also request compensation for non-refundable purchases like tours, hotel bookings, and other activities planned around the mistake fare.

Nonetheless, it’s still strongly recommended that travelers who think they’re booking a fare published in error wait until the flight has been ticketed to make additional travel plans.

This article originally appeared on TravelandLeisure.com