The 22" fit on a Southwest 737, but I found myself using the 18" a lot more, since it holds almost as much and is easier to move through the airport. Lately, I've been condemned to fly in little commuter jets for at least one leg of each trip and am using a large backpack and little wheeled cabin tote. The backpack holds everything the 22" holds and squeezes in to much smaller places. It's very nice to not have to gate check.