Carrier route record
F9PHL→DEN
Frontier Airlines · Philadelphia to Denver
- Flights
- 296
- Period
- July 2025 to June 2026
- Share of route
- 10%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.
Frontier on PHL 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, 9 points worse than the national rate of 77.6%. The late ones land close to two hours behind schedule. That rests on 296 flights. The strongest carrier on the route with a full sample, United Airlines, flew 953 at 83.9% on time.
United Airlines is the most reliable of the three carriers covered here at 83.9% on time across 953 flights.
Key figures
On time
68.4%
Arrivals under 15 minutes late, of 291 completed flights
Avg delay
112 min
Across delayed arrivals only, not all flights
Cancelled
1.69%
National rate is 1.81%
Whole route
74.9%
Every carrier on PHL to DEN, 3,005 flights
These figures cover 296 flights between July 2025 and June 2026. Beyond the headline rate, 12.4% 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 PHL to DEN
Frontier flew 296 of the 3,005 flights on PHL to DEN, about 10% of it. Its 68.4% on time is 7 points worse than the route as a whole, which runs 74.9%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from United at 83.9% to Frontier at 68.4%.
The choice of carrier is not cosmetic here. United Airlines arrives on time 83.9% of the time; Southwest Airlines manages 69.0%. Sample sizes sit next to every figure, because a two-point gap across 879 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 953 | 83.9% | 92 min | 0.84% | B+ |
| American Airlines | 877 | 73.3% | 66 min | 1.60% | C |
| Southwest Airlines | 879 | 69.0% | 57 min | 0.80% | C+ |
| Frontier Airlines (this page)thin sample | 296 | 68.4% | 112 min | 1.69% | C |
The spread between United and Southwest is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
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 26 points, against 15 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am115 flights81.7%
- 8am–11am—
- 11am–2pm50 flights64.0%
- 2pm–5pm—
- 5pm–8pm15 flights—
- 8pm–5am116 flights56.2%
Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 56.2% on time, against 81.7% for the 5am–8am 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 116 flights scheduled in it.
Across the year
Frontier on PHL to DEN through the year
- Jul–Sep 2025101 flights73.3%
- Oct–Dec 202557 flights76.4%
- Jan–Mar 202638 flights52.8%
- Apr–Jun 2026100 flights64.6%
Scale runs 45% to 80%. Rows with fewer than 30 flights show a dash.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 68.4% on time across 296 flights.
Frontier on PHL to DEN did not run the same all year. Its best quarter was Oct–Dec 2025 at 76.4% on time and its weakest Jan–Mar 2026 at 52.8%, a swing of 24 points on roughly 74 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
Across the week, Saturday is the strongest day at 73.7% on time and Sunday the weakest at 58.5%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Frontier runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 10,000 reported delay minutes.
- 42%Carrier
- 33%Late-arriving aircraft
- 15%National Airspace System
- 9%Extreme weather
The largest share of delay minutes, 42%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 4,317 of the 10,000 delay minutes reported here. The split is drawn from 10,299 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 81.7% on time here.
Cancellations sit at 1.69% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
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. 12.4% 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.
At 1,558 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 62.3% on time across 295 flights, 6 points below 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 6 points of difference.
One caution: this is a thin sample. 296 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 PHL to DEN
Put together: treat all of this as provisional. 296 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 68.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 291 completed flights over 12 months sit behind that.
Related
Where to go next
- PHL to DEN, every carrier
- Frontier on DEN to PHL, the return leg
- United Airlines on PHL to DEN83.9%
- American Airlines on PHL to DEN73.3%
- Southwest Airlines on PHL to DEN69.0%
- Frontier Airlines network-wide record
- Philadelphia International (PHL) delay statistics
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.