Passengers aboard a Denver-bound flight last year spent seven hours stuck on a tarmac, one example of the rapidly increasing “tarmac delays” that air travelers face, according to a new study.
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The overall on-time performance of U.S. airlines has reached its worst level since 2014, with nearly a quarter of flights delayed, diverted, or canceled, according to the “Plane Truth 2026” study, which the consumer watchdog group CoPIRG unveiled Tuesday. One in 12 flights in 2025 arrived an hour or more late, the study found.
In Colorado, the on-time arrival rates at Denver International Airport (75.4%) and the Colorado Springs Airport (73.1%) both ranked below the national average of 76.3% for the largest U.S. airlines. Denver-based Frontier Airlines, for the fourth year in a row, ranked worst among major airlines for customer complaints and involuntary passenger bumpings.
The study draws on federal data collected by the U.S. Department of Transportation from airlines. It presents a picture of air travel becoming more of a hassle for travelers, ahead of the busy summer travel months when complaints typically peak.
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Travelers this summer can expect “erratic and stressful adventures,” CoPIRG’s Colorado director Danny Katz said after presenting study findings at Denver Union Station.
“It is dumbfounding that we are having people sit on their planes for more than three hours and not holding airlines accountable,” Katz said. “Congress should take action. The Trump Administration should take action.”
U.S. airline tarmac delays exceeding three hours increased to 708 in 2025, up by 63% from 435 in 2024 and 2.4 times higher than the 289 in 2023, according to the federal data in the 44-page study. Tarmac delays exceeding four hours on international flights increased to 77, up from 64 in 2024.
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