DENVER — The Colorado Public Interest Research Group says 2025 brought the worst nationwide on-time arrival rate since 2014, with Denver-based Frontier Airlines among the poorest performers.
Frontier had the highest percentage of flights arriving more than an hour late and ranked in the top three worst carriers for cancellations and involuntary bumping, according to CoPIRG’s annual Plane Truth 2026 analysis.
Southwest Airlines was among the best for on-time arrivals.
Report highlights
- One in nine flights arrived 45 minutes or more late
- One in 12 flights arrived over an hour late
- Domestic tarmac delays lasting more than three hours rose 63% compared with 2024
- Denver International Airport’s on-time arrival rate was 75.4%, below the national average of 76.3%
- Colorado Springs’ on-time arrival rate was 73.1%, with its departure rate of 78.3% higher than DIA’s 73.9%
CoPIRG Executive Director Danny Katz said travelers should expect “erratic and stressful” flights during the busy summer travel season.
"Last year, one in 12 flights arrived 60 minutes or more late," Katz said. "You can’t just buy your flight and assume everything is going to go all right."
Katz pointed to overcrowded airports, overscheduled flights, fewer air traffic controllers, summer weather patterns and weak enforcement of passenger protections as key factors.
For example, airlines can be fined $27,500 per passenger for tarmac delays over three hours, but Katz said enforcement has been lacking.
► Watch Jaclyn Allen's report in the player below:
"It’s dumbfounding that we have people sitting on these planes for more than three hours, and yet we’re not holding those airlines accountable," he said.
Jennifer de la Cruz, senior director of corporate communications for Frontier, responded to the report: "We are strongly focused on improving operational reliability. We have launched a revamped system-wide maintenance strategy, along with enhanced airport operations… We are seeing positive early results, and year to date through April, we ranked fourth among major domestic carriers in completion factor. We anticipate further improvements as various initiatives are fully implemented."
Frontier passengers told Denver7 that higher fees add to frustrations.
Hannah Taylor said she had to "completely rearrange everything and pull like a pound of stuff out" of her luggage to avoid a $75 overweight fee.
"Seats are smaller, everything’s overpriced — it’s just getting worse," she said.
The report also found a few bright spots. Mishandled baggage and wheelchair handling rates improved slightly in 2025. Airlines mishandled about 2.43 million bags last year, but the rate dropped from 0.55 per 100 checked bags in 2024 to 0.52 in 2025.
Even with growing delays, Katz said passengers can improve their odds:
- Book early morning flights and fly direct when possible
- Check flight history before purchase
- Put a tracker in checked baggage
- Download the airline’s app for delay and cancellation alerts
- Know your right to a refund if your flight is canceled for any reason
- File complaints with the U.S. Department of Transportation. (Katz says documenting problems helps strengthen enforcement.)
The Best and Worst Airlines, According to Plane Truth 2026
Cancellations
Best (lowest percentage of cancellations): Allegiant, Hawaiian, Southwest
Worst (highest percentage of cancellations): American, Frontier, JetBlue
On-Time Arrivals
Best (highest on-time percentage): Hawaiian, Delta, Southwest
Worst (lowest on-time percentage): Frontier, JetBlue, American
Damaged and Lost Baggage
Best (lowest percentage mishandled): Allegiant, JetBlue, Southwest
Worst (highest percentage mishandled): United, American, Hawaiian
Damaged and Lost Wheelchairs
Best (lowest percentage mishandled): Delta, Allegiant, United
Worst (highest percentage mishandled): JetBlue, Frontier, American
Involuntary Bumping
Best (lowest percentage bumped): Delta and Allegiant (tied for No. 1), Southwest
Worst (highest percentage bumped): Frontier, American, Spirit
