Air travel is getting worse. That’s what passengers are telling the U.S. government.

WASHINGTON — Air travel got more miserable last year, if the number of consumer complaints filed with the U.S. government is any measure.

The Transportation Department said Friday that it received nearly 97,000 complaints in 2023, up from about 86,000 the year before. The department said there were so many complaints that it took until July to sort through the filings and compile the figures.

That’s the highest number of consumer complaints about airlines since 2020, when airlines were slow to give customers refunds after the coronavirus pandemic shut down air travel.

The increase in complaints came even as airlines canceled far fewer U.S. flights — 116,700, or 1.2% of the total, last year, compared with about 210,500, or 2.3%, in 2022, according to FlightAware data. However, delays remained stubbornly high last year, at around 21% of all flights.

So far this year, cancellations remain relatively low — about 1.3% of all flights — but delays are still running around 21%.

More than two-thirds of all complaints last year dealt with U.S. airlines, but a quarter covered foreign airlines. Most of the rest were about travel agents and tour operators.

Complaints about treating passengers with disabilities rose by more than one-fourth compared with 2022. Complaints of discrimination, while small in number, also rose sharply. Most were about race or national origin.

The Transportation Department said the increase in complaints was partly the result of more consumers knowing about their rights and the ability to file a complaint. The department said it helped Southwest Airlines customers get more than $600 million in refunds and reimbursements after the carrier canceled nearly 17,000 flights during December 2022. Southwest also paid a $35 million fine.

Airlines receive many more complaints from travelers who don’t know how or don’t bother to complain to the government, but the carriers don’t release those numbers.

The Transportation Department is modernizing its complaint-taking system, which the agency says will help it do a better job overseeing the airline industry. However, the department now releases complaint numbers many months late. It did not issue figures for the second half of 2023 until Friday.