A new study ranked the best and worst airlines for pets, based on U.S. Department of Transportation’s pet incident data from 2017–2018. The DOT keeps a detailed list of animal incidents on air carriers, including animal injuries, losses and deaths.

While incident data doesn’t always tell the full story, it does give some indication of an airline’s incident rate and pet policies. This list represents more than 400,000 animals traveling by air and doesn’t include animals transported by cargo.

According to the 2017–2018 data, the best airline for pet policies, based on incidences, is Alaska Airlines, with just one reported injury in 2018. Last year, Alaska Airlines transported 143,634 animals — 34 percent of all transported animals across all airlines — and boasts the best track record for both 2017 and 2018.

The worst pet policy airline according to the incident study: Hawaiian Airlines. With three reported animal deaths of only 9,500 transported, Hawaiian’s incident rate is the worst for 2018.

However, more animals onboard Delta Air Lines died than any other airline in 2018. According to DOT’s February 2019 Air Travel Consumer Report, four animals died onboard Delta Air Lines. Between Hawaiian Airlines’ three recorded animal deaths, United Airlines’ two and American Airlines’ one, Delta technically had the worst year. This is not reflected in the incident report, as the greater number of transported animals balanced the statistics in Delta’s favor.

A better way to travel with pets overall, according to the Humane Society: Travelers should bring their pets along with them in the main cabin — not in cargo and never in the overhead bin. Pets should be kept in carriers they can stand up and turn around in and be at least 8 weeks old. Additionally, airlines may require health certificates and vet records for traveling pets.