Alaska Airlines is the number one ranked airline for the second year in a row, just barely beating out Delta, according to a report from Embry-Riddle Aeronautical University's College of Aviation.

The details: The study examined four main criteria, including customer complaints, denied boardings, mishandled baggage, and on-time arrivals.

• Alaska Airlines saw an improvement in one area: "involuntary denied boardings per 10,000 passengers." But it did worse in the other three criteria.
• The airline with the biggest number of complaints: Spirit Airlines, with 5.59 complaints per 100,000 passengers. (The industry average was 1.35.)

The big picture: Dr. Dean Headley, one of the authors of the study, told Axios that the "airline industry got better this year," which proves that "when they want to, they can change things." But, there's still a ways to go.

Flashback: Around this time last year, United experienced a major PR crisis when video surfaced of a man being dragged from the plane. Headley said that incident caused the industry to cut the "involuntary denied boarding rate by half."

The publicity surrounding that incident was what caused the change, but Headley asks: "Does it really take a dramatic incident for them to do the right thing?"