It has been a tumultuous year for the airline industry as carriers continually faced weather disruptions, COVID-related staffing woes and a shortage of aircraft.
The issues persisted as passengers flooded back to airports. However, according to the annual Airline Quality Rating from Wichita State University, some passenger carriers were able to outshine others in overall performance.
The study examines each airline based on mishandled baggage, consumer complaints, on-time performance and involuntary denied boardings.
Dallas-based Southwest Airlines was rated the best in overall performance, outranking its competitors for the second year in a row.
One of the reasons why it's so highly regarded is because it was able to keep its customers satisfied over the past two years.
Dean Headley, the author of the report, told FOX Business that every airline faced complaints when the pandemic first brought travel to a standstill, and over 80% of them were regarding refunds for passengers.
However, Southwest figured out how to "make their customers a little more whole" the fastest, he added. It took the carrier until around July or August to figure out how to help customers, while "some of the airlines still haven't figured that one out," Headley said. "They're still making people unhappy about holding on to their money when they can't fly."
Southwest continued to handle this well even into 2021, he said.
However, when broken down by categories, Hawaiian Airlines was the top-ranked carrier when it came to best on-time performance. Meanwhile, Delta Air Lines had the lowest consumer complaint rate, and Allegiant had the best baggage-handling performance.
Additionally, Allegiant, Delta, Hawaiian and United had the lowest involuntary denied boarding rates. This means they had the fewest number of passengers who were denied boarding due to overbooking or whose flight departed without them.
Comparatively, Allegiant had the worst on-time performance and American had the worst baggage-handling performance. Spirit had the highest consumer complaint rate.
Here is the 2021 ranking of the nation’s 10 largest airlines
Still, the study's researchers found that, across the industry, fewer planes arrived on time, more baggage was mishandled and more passengers with booked tickets were bumped from their flights.
COVID-related staffing woes and low plane inventory are driving these issues, according to Headley.