Carrier route record
F9ATL→DEN
Frontier Airlines · Atlanta to Denver
- Flights
- 738
- Period
- July 2025 to June 2026
- Share of route
- 13%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.
Frontier on ATL to DEN sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 738 flights. The strongest carrier on the route with a full sample, United Airlines, flew 967 at 85.6% on time.
United Airlines is the most reliable of the three carriers covered here at 85.6% on time across 967 flights.
Key figures
On time
70.9%
Arrivals under 15 minutes late, of 726 completed flights
Avg delay
82 min
Across delayed arrivals only, not all flights
Cancelled
1.36%
National rate is 1.81%
Whole route
77.6%
Every carrier on ATL to DEN, 5,589 flights
These figures cover 738 flights between July 2025 and June 2026. Beyond the headline rate, 10.2% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Frontier against every carrier on ATL to DEN
Frontier flew 738 of the 5,589 flights on ATL to DEN, about 13% of it. Its 70.9% on time is 7 points worse than the route as a whole, which runs 77.6%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from United at 85.6% to Frontier at 70.9%.
The choice of carrier is not cosmetic here. United Airlines arrives on time 85.6% of the time; Southwest Airlines manages 73.4%. Sample sizes sit next to every figure, because a two-point gap across 1,079 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 967 | 85.6% | 78 min | 0.41% | A+ |
| Delta Air Lines | 2,805 | 78.1% | 52 min | 1.11% | B |
| Southwest Airlines | 1,079 | 73.4% | 54 min | 1.11% | C |
| Frontier Airlines (this page) | 738 | 70.9% | 82 min | 1.36% | C |
The spread between United and Southwest is 12 points, wide enough that it should decide the booking. On a hundred trips that is 12 more arrivals inside the on-time window.
Flight by flight
Frontier flight numbers on ATL to DEN
Departure window
When Frontier runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am240 flights77.5%
- 8am–11am117 flights77.2%
- 11am–2pm72 flights83.3%
- 2pm–5pm7 flights—
- 5pm–8pm41 flights58.5%
- 8pm–5am261 flights59.8%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 58.5% on time, against 83.3% for the 11am–2pm slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8pm–5am window is the busiest, with 261 flights scheduled in it.
Across the year
Frontier on ATL to DEN through the year
July is the worst month at 55.9% on time, 23 points below January, the best at 78.7%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. June was the busiest month here, with 89 flights.
Across the week, Wednesday is the strongest day at 77.1% on time and Sunday the weakest at 65.1%. 12 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Frontier runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 48% of the 17,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 48%Late-arriving aircraft
- 31%Carrier
- 15%National Airspace System
- 6%Extreme weather
48% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 17,000 reported delay minutes here, that single category outweighs weather by 8 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 17,188 reported delay minutes.
Cancellations sit at 1.36% against a national 1.81%, which is ordinary. Diversions add another 0.27%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.2% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 1,199 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 78.9% on time across 744 flights, 8 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 8 points of difference.
One caution: this is a thin sample. 738 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking Frontier on ATL to DEN
Put together: treat all of this as provisional. 738 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 70.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 726 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to DEN, every carrier
- Frontier on DEN to ATL, the return leg
- United Airlines on ATL to DEN85.6%
- Delta Air Lines on ATL to DEN78.1%
- Southwest Airlines on ATL to DEN73.4%
- Frontier Airlines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Denver International (DEN) delay statistics
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.