Finding the best rate on airfare is tricky no matter how often you fly, with prices often changing frequently and without rhyme or reason. Luckily, travelers who have a little more flexibility can take advantage of some of the cheapest tickets around: airline mistake fares.

What Exactly Is an Airline Mistake Fare?

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Airline mistake fares are cheap tickets — really cheap tickets — that come about as a result of an error in the price listing. So rather than paying, for example, $15,000 for a round-trip business class flight from San Francisco to New Zealand, you could pay $1,500 — a mistake fare that occurred in 2007 due to an agent forgetting to type the extra zero.

What Causes Mistake Fares?

There is no single cause for mistake fares. Some, like the example above, are caused by human error. With the number of fares listed every day, it is simply impossible to catch every mistake.

Other mistake fares are caused by computer glitches. Many airlines use algorithms to determine airfare, and these algorithms sometimes make mistakes. For example, if your flight requires a lot of transfers, the algorithm might accidentally drop the fuel surcharge that you'd generally have to pay.

Even if the computer is working perfectly, sudden changes in foreign currency — or mistakes made while converting these currencies — can cause drastically reduced ticket prices.

How to Track Down Mistake Fares

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So how exactly do you find these great deals?

A great place to start is by familiarizing yourself with websites specifically designed to keep track of airline prices, such as Seeqr, the site you're on right now, and Airfare Watchdog. Utilizing these sites allows you to track certain flight routes and get alerts any time ticket prices for these routes drop. Many sites specifically look for these under-priced tickets and let you know right away when a mistake fare becomes available. When you utilize this sort of service, you can sign up for email alerts to get notifications about specific routes.

If you'd rather track prices yourself, you can certainly do that too. Make sure you know how much tickets usually go for so that you'll be able to spot a mistake when it appears. By regularly checking airfares, you'll also start to notice trends in when prices rise and fall — knowledge that's handy even if you don't find any mistake fares.

Tips for Taking Advantage of Mistake Fares

Once you find a mistake fare, it's important to act quickly. These tickets tend to either sell out or get removed once the airline realizes its mistake. A great option to make sure your purchase goes through before the fare is removed is to purchase your ticket directly through the airline. This speeds up the buying process, making it more likely your fare will be honored. Buying directly from the airline also ensures that you will have 24 hours to get a refund if you decide you don't want the ticket after all. This is important, as the rapid-fire nature of mistake fares often means you don't have much time to think before you make the purchase. With a 24-hour grace period, you can jump on the ticket opportunity with the knowledge that you can change your mind if need be.

It is also important not to book too many non-refundable plans for your trip immediately after purchasing your ticket. Although it is unlikely that the airline will suddenly cancel your tickets when they realize the mistake, they do have that option. This means it's usually smarter to wait a week or two after your purchase before you make any other plans for your trip.

Do Airlines Have to Honor Mistake Fares?

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As of 2015, U.S.-based airlines are not legally required to honor your mistake fare. If they do cancel your ticket, they are required to reimburse you. Technically, they are also required to repay you for any non-refundable expenses — such as a hotel booking — that you incurred when you thought you had purchased your ticket. This is important to know, as airlines will not necessarily advertise this fact if they do cancel your ticket.

However, just because airlines are legally able to cancel tickets purchased under a mistake fare doesn't always mean that they will. Regularly canceling customers' tickets leads to bad press for the airline, which may ultimately cost more than simply honoring the mistake fare. Ultimately, the likelihood that your mistake fare will be honored comes down to how big of a mistake it was — airlines will most likely let smaller mistakes slide, while they may cancel tickets if the mistake was too big.

So if the price seems too good to be true, it might be, but that doesn't mean you shouldn't purchase the ticket anyway! Worst case scenario, the airline will simply refund your money (and they might even compensate you with some extra travel miles to make up for the inconvenience).

Importance of Flexibility

One of the most important things to keep in mind when searching for mistake fares is the need to be flexible. If you have to go to a specific place at a specific time, it simply isn't feasible to wait around for the perfect mistake fare to pop up. But one of the biggest benefits of mistake fares — other than the incredible savings — is that they give you the chance to be spontaneous, and to travel somewhere you might never have gone otherwise. If you're able to keep an open mind and a flexible schedule, mistake fares are a wonderful way to let you see the world on a budget.