72% of flights from Denver to Philadelphia arrived on time over the past 12 months. That is worse than the typical U.S. route. The 7 a.m. departures ran on time 88% of the time; the 7 p.m. ones 38%. Most reliable airline: United Airlines (78%). 11% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for DEN → PHL: when a flight was late, it was under 45 minutes late 52% of the time. About 1 in 10 flights landed an hour or more late, and 1 in 46 three hours or more; 1.4% were cancelled outright.
- On time or early72%
- 15–30 min late9.1%
- 30–60 min late7.8%
- 1–2 hours late5.4%
- 2–3 hours late2.3%
- 3+ hours late2.2%
- Diverted0.2%
- Cancelled1.4%
Share of all 3,056 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| United Airlines | 952 | 78% | 0.5% | −5 min | 7.5% | +71 min | United Airlines |
| American Airlines | 925 | 77% | 2.2% | −13 min | 9.3% | +113 min | American Airlines |
| Southwest Airlines | 880 | 61% | 0.9% | +7 min | 11.7% | +59 min | Southwest Airlines |
| Frontier Airlines | 299 | 66% | 3.7% | 0 min | 13.7% | +101 min | Frontier Airlines |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at DEN). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | United Airlines | American Airlines | Southwest Airlines | Frontier Airlines |
|---|---|---|---|---|
| 7 a.m. | — | 87% | — | — |
| 8 a.m. | — | 84% | — | — |
| 10 a.m. | 88% | — | 77% | — |
| noon | — | 72% | — | — |
| 1 p.m. | 80% | — | — | — |
| 2 p.m. | — | 68% | — | — |
| 5 p.m. | 70% | — | — | — |
| 6 p.m. | — | — | 40% | — |
| 7 p.m. | — | — | 34% | — |
| 11 p.m. | — | — | — | 57% |
Last flight of the day
On DEN → PHL, each airline's last flight of the day was cancelled 2.1% of the time, against 0.9% for its earlier flights (2.3× as often). It arrived 3+ hours late 3.2% of the time (earlier flights: 1.7%). It matters more than the numbers suggest. Miss an earlier flight and there's another one that evening; miss the last one and you're usually waiting until morning.
| Airline | Last departure | Last: cancelled | Last: 3h+ late | Earlier: cancelled | Next morning |
|---|---|---|---|---|---|
| American Airlines | 11:55 p.m. | 2.2% | 4.7% | 2.0% | first flight 8:41 a.m. |
| United Airlines | 11:59 p.m. | 1.1% | 1.1% | 0.2% | first flight 9:35 a.m. |
| Southwest Airlines | 7:05 p.m. | 1.7% | 3.1% | 0.4% | first flight 10:30 a.m. |
Last flight = the airline's last scheduled departure on this route that day, on days it flies the route at least twice; past 12 months. Times are typical scheduled times over the latest three months.
If you need to be in PHL tonight, book an earlier flight so there's a backup if it's cancelled.
By month
Each calendar month pooled over 2023–2026. Best: November (80%). Worst: July (64%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 461 | 66% | 0.9% |
| Tuesday | 391 | 80% | 1.5% |
| Wednesday | 418 | 76% | 0.2% |
| Thursday | 460 | 67% | 0.9% |
| Friday | 473 | 72% | 2.1% |
| Saturday | 393 | 75% | 1.3% |
| Sunday | 460 | 68% | 3.0% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 33 · airline 8 · air traffic/airport 3
Month by month
Flight numbers on this route
Regular flights with at least 120 scheduled trips in the past year. Sorted by departure time.
| Flight | Departs | Flights | On time | Cancelled | Typical arrival | Operated by |
|---|---|---|---|---|---|---|
| AA 516 | 8:40 a.m. | 131 | 86% | 1.5% | −15 min | American Airlines |
| UA 1575 | 9:35 a.m. | 301 | 87% | 0.3% | −9 min | United Airlines |
| UA 1510 | 5:54 p.m. | 123 | 54% | 0.8% | +11 min | United Airlines |
| F9 3340 | 11:59 p.m. | 232 | 59% | 4.3% | +3 min | Frontier Airlines |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Mar 15, 2026 | 7 | 0% | 1 |
| Mar 16, 2026 | 7 | 0% | 0 |
| Jan 25, 2026 | 5 | 0% | 5 |
| Dec 19, 2025 | 10 | 10% | 1 |
| Mar 6, 2026 | 7 | 14% | 0 |
Questions
How often are flights from DEN to PHL on time?
72% of 3,056 scheduled flights from Denver, CO to Philadelphia, PA arrived within 15 minutes of schedule between September 2025 and August 2026. 1.4% were cancelled.
What is the best time of day to fly DEN to PHL?
Flights scheduled to leave at 7 a.m. were the most reliable (88% on time). The 7 p.m. departures were the least (38%).
Which airline is most on time from DEN to PHL?
United Airlines: 78% of its 952 flights on the route arrived on time. American Airlines: 77%. Southwest Airlines: 61%. Frontier Airlines: 66%.
What month has the most delays from DEN to PHL?
July (64% on time). The best month is November (80%), over 2023–2026.
Is the last flight of the day from DEN to PHL more likely to be cancelled?
Yes. Each airline's last DEN–PHL flight of the day was cancelled 2.1% of the time over the past year, against 0.9% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- PHL → DEN (return)
- Denver (DEN) delays by hour
- Flights into Philadelphia (PHL)
- United Airlines on-time record
- American Airlines on-time record
- Southwest Airlines on-time record
- Frontier Airlines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.