If you’re planning a vacation or business trip in the coming months, sometimes it’s hard to avoid a connecting flight—especially if you’re departing from or heading to a smaller city. Recent data from the U.S. Department of Transportation’s October 2018 Air Travel Consumer Report sheds light on which airports you should avoid if you’re planning a flight with a tight connection based on on-time arrival statistics at the nation’s 30 largest airports.

Many of these airports can be hard to avoid due to the “hub and spoke” model that most U.S. airlines use. If you find yourself connecting through one of these cities, there are a few tips you can use avoid missing your connection:

First, give yourself a 60 – 90-minute window for a connection. This will give you some padding if your flight arrives late, or you’re seated at the back of a large plane and are one of the last passengers to deplane.

Most airlines utilize a single area for their gates, or can at least keep you in the same concourse or terminal, in an effort to make connections easy for passengers.

Finally, connections earlier in the day also have a better chance of being on time. As delays occur throughout the day, their effects continue to compound as the day continues, which can impact late-day flights. Flying earlier in the day can help you get on a new same-day flight in the event you miss a connection.