(NewsNation Now) — Any time thousands of flights are canceled, there are bound to be plenty of unhappy passengers.

Some airlines seem to handle cancellations better than others, but which airline gets the most complaints?

Here is what we know:

Among the major U.S. air carriers, there’s one airline — where “your bags fly free.” — that consistently garners the fewest passenger complaints.

Southwest is the only airline to have any month last year with fewer than one complaint per 100,000 bookings. And they had three months of that success.

Since May of 2020, only two U.S.-based airlines that had less than seven consumer complaints per 100,000 passengers, Southwest and Delta.

On the other side of the spectrum, the most complained-about airline in the country is Frontier. Last year, the low-cost carrier had nearly seven times the passenger complaints of Delta.

Ranking second for most complaints was Hawaiian Airlines, and in third place, United.

Then you see a huge drop-off in the number of complaints. JetBlue, the fourth-most complained-about airline, still had almost one-third the passenger issues as United.

No matter the cost of the ticket — whether it’s a $29 Frontier fare or a first-class United seat — passengers don’t appear hesitant to complain when an airline gets between them and their destination.