Complaints in the US about airlines decreased in the first month of the year, the government has announced, despite registering almost 11,000 such reports from passengers.
The number of complaints fell by 35.9% from the 16,876 received in December 2022, but was up 111.7 % year-on-year, the transportation department said.
More than 70% of the complaints were against US carriers, according to the data, with 24% concerning foreign airlines and around 4% directed at travel agencies.
Almost a quarter of the complaints were against Southwest Airlines and were about what the department described as "the 2022 holiday travel problems that stranded millions".
The department said it is "conducting a rigorous and comprehensive investigation into this incident and has made clear to Southwest that it must provide timely refunds and reimbursements" or face legal action.
Around one-fifth of complaints were about refunds, with almost 17% of these aimed at Southwest.
Over 18% of the complaints were about luggage, with 40% of these against foreign airline, while over 37% of the complaints concerned cancellations, delays and "other deviations from airlines’ schedules".