Airline complaints soared 1,500% in April as flyers vented about refunds

April was a rough month to be an airline.

In addition to plummeting demand from travelers and severely constrained finances, consumer complaints reached what may have been a new record high.

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Passengers filed 19,856 complaints about airline service in April, according to data released by the Department of Transportation on Friday. That's up from 5,064 in March and from 1,206 in April 2019 — a whopping 1,546% year-over-year increase.

In a press release announcing April's aviation statistics, the DOT said that 17,387 of the service-related complaints that month had to do with refunds.

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That refunds drove most of the complaints is little surprise. Some airlines initially resisted efforts to give refunds for canceled flights, pushing travelers to accept vouchers instead as they tried to conserve cash while demand for travel bottomed out in April. Many passengers began to complain, and the DOT eventually issued a public rebuke to carriers with a sternly worded reminder that refunds were required by law when an airline cancels a flight.

The DOT had already recorded a spike in refund complaints in March, even though carriers operated close to normally through the first half of the month. The report released Friday that includes April's numbers is the first to capture an entire month's effect of the pandemic on U.S. airline operations.

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Among the nuggets: It's remarkable to note that the deluge of complaints — up by more than 18,000 from the prior year — came even as the number of travelers was down as much as 96% compared to April 2019, based on Transportation Security Administration screening data.

April saw demand for travel fall precipitously, with airlines quickly slashing service as passenger levels suddenly dropped to historically low numbers.

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The April shakeup also led to an odd reshuffling of the aviation industry landscape, temporarily crowning Southwest the world's largest airline by seat count. In April, the DOT fielded 521 refund-related complaints against Southwest, which wasn't bad for the world's largest airline.

At the other end of the spectrum, however, was United. The carrier lodged more than 2,700 refund-related complaints in April alone. The carrier was among those that made receiving refunds difficult, and that appears to borne out in the DOT complaint numbers for the month.

American, which generally has had one of the industry's most generous refund policies, fielded the second-most refund complaints in April with 1,173. Frontier (850), Delta (732) and Southwest rounded out the top five for refund complaints in April.

April also saw airlines implement new onboard public health measures, with many carriers announcing mask-wearing requirements that month. There still isn't a federal policy requiring masks while traveling, but most airlines now have such a rule in place.

Travel experience: What it’s like to fly a low-cost airline during a pandemic.

The DOT has since issued more warnings to airlines about refunds, so it seems likely that May could show high numbers in that area as well.

But the complaint numbers were far from the only ones in the DOT's April report to bear out the dramatic impact that the coronavirus had on U.S. airlines during the month.

Commercial U.S. carriers completed just 194,390 flights during the month — the lowest monthly total since February 1994, when airlines completed 370,027 flights.

Among the other numbers in the April report: 41.3% of scheduled flights during the month were canceled, underscoring the havoc the pandemic unleashed on the industry. Similarly, the industry's on-time arrival rate of just 55.7% was the lowest monthly on-time arrival performance since reporting began in 1987.