Air travel not only costs you money—it can also end up costing you a lot of valuable time otherwise spent at your destination. No matter how much you pay to secure a seat on a plane, flight delays and cancellations are impossible to anticipate. Fortunately, there are cases where airlines will compensate you for that lost time, and a new service called AirHelp makes it easier to claim the money you’re owed.

To use AirHelp, you can start by either visiting the website or downloading the app from the App Store or Google Play. Next, submit the information for a flight you had booked sometime in the past three years that was disrupted. If you were set to fly out of New York to Chicago last Thanksgiving, for example, you would input the names of both airports, give the airline, flight number, and departure date, and specify if the flight was delayed, canceled, or if you were bumped from the flight and how long you were left waiting at the airport (you can also say what reason the airline gave you, if you remember). Based on this information, AirHelp will tell you if you’re eligible for compensation and how much is owed. That way, you can reach out to the airline knowing what to expect.

According to AirHelp, over 9 million air passengers are eligible for compensation for disrupted flights annually, but many of them never follow up with the airlines that owe them money. More than $413 million was left unclaimed in 2017 just from delayed flights from the U.S. to Europe. That means that people are missing out on up to hundreds of dollars per flight that could be funding their next getaway.

If you’re one of the many flyers who was inconvenienced by bad weather this winter, check AirHelp to see if it's worth pursuing a claim. Here are some tips for receiving the biggest flight reimbursement possible.