U.S. airlines packed passengers onto planes at a record rate in the first eight months of the year.
The share of filled seats, known as the load factor, reached 84.1 percent for domestic and international flights for the period from January through August, according to the U.S. Bureau of Transportation Statistics.
The higher load factor means fewer empty seats for last-minute travelers and for fliers hoping to trade in loyalty reward points, said Rick Seaney, founder of the airfare-monitoring site Farecompare.com.
Plus, airlines have fewer seats for passengers whose flights are canceled, he said.
That may also explain why complaints against airlines in the first nine months of the year rose from 10,444 to 12,350, an 18.2 percent increase, according to federal statistics.
The load factor exceeded the previous high for the same period in 2013, when it was 83.7 percent, the agency said. The load factor for domestic flights was even higher, 85.3 percent for the eight-month period, compared with 84.1 percent last year.
The U.S. airline industry has been reporting record profits this year, partly because carriers have kept a tight rein on capacity while demand for air travel has continued to grow.
U.S. airlines posted a combined $3.6 billion in profits in the period from April through June, a 64 percent increase over a year earlier, according to federal data.