Route profile
DEN→PHL
Flight reliability, delays and best times to fly from Denver to Philadelphia, 1,558 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 24% of comparable major US routes (4,598 compared)
Calculated from 9,312 flights. How this is calculated
DEN → PHL arrives on time 73.1% of the time; the return trip, PHL → DEN, arrives on time 76.8% of the time, a 3.7-point gap between the two directions of the same city pair.
DEN → PHL spends 27.5 minutes on the ground on a 1,558-mile trip: 19.2 minutes from pushback to wheels-up at DEN and 8.3 minutes from touchdown to gate at PHL.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
This route has stayed remarkably steady year over year, a smaller swing than 97% of 5,368 comparable routes.
73.5% on time over the most recent 12 months (2025-08 to 2026-07), against 73.7% in the 12 months before (2024-08 to 2025-07), virtually unchanged.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 5,368 in the comparison.
What sets this route apart
Where DEN to PHL differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
DEN to PHL struggles most at 7 PM: 44.6% of its flights scheduled then arrive on time, 22 points behind the 66.6% on routes of similar length at the same hour. Against all other routes the gap is 23.2 points.
DEN to PHL is at its best against routes of similar length for flights scheduled at 10 AM: 82.9% arrive on time, 2.8 points ahead of the 80.1% those routes manage at that hour.
Monday is the day DEN to PHL slips furthest against routes of similar length, 70.9% on time where they average 77.0%, 6.1 points lower. Against all other routes the gap is 6.4 points.
In September, DEN to PHL runs 7.2 points below routes of similar length, 74.9% on time to 82.1%. Against all other routes the gap is 7.5 points.
Southwest Airlines’ flights on DEN to PHL arrive on time 65.8% of the time, 9.8 points below the 75.6% it manages on its routes of similar length. Against all other routes the gap is 11.6 points.
DEN to PHL against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 7 PM departures | 44.6% | routes of similar length | 66.6% | −22.0 pts | 312 here, 67,625 there |
| Hour: 10 AM departures | 82.9% | routes of similar length | 80.1% | +2.8 pts | 1,255 here, 88,930 there |
| Weekday: Monday | 70.9% | routes of similar length | 77.0% | −6.1 pts | 1,356 here, 239,178 there |
| Month: September | 74.9% | routes of similar length | 82.1% | −7.2 pts | 828 here, 127,663 there |
| Airline: Southwest Airlines | 65.8% | routes of similar length | 75.6% | −9.8 pts | 2,436 here, 343,080 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,558 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
Why DEN → PHL flights are cancelled
July 2023 – July 2026
DEN → PHL cancelled 112 of 9,312 scheduled flights — about 1 in every 83. The reason filed most often was extreme weather, 70.5% of the cancellations coded on this route — about 1 in every 118 scheduled flights.
Share of cancellations
Of 112 cancelled departures carrying a reason code.
What each reason means
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
79 cancellations, 70.5% of the total.
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
28 cancellations, 25.0% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
5 cancellations, 4.5% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
112 coded cancellations were recorded on DEN → PHL; the section appears from 50.
When it goes wrong
July 2023 – July 2026
55 min late
against a median of 2 min early
Percentiles over 9,312 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at PHL after arriving from DEN.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 45% | Likely to miss |
| 45 min | 26% | High risk |
| 60 min | 17% | High risk |
| 90 min | 9.0% | Some risk |
| 120 min | 5.4% | Some risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.20% of the time and diverts 0.27% of the time, which a late arrival never shows up in.
Chance of missing is the share of 9,175 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 55 minutes late (90th-percentile gate arrival delay), over 9,312 operations.
Any other layover length: connection checker.
Best time to fly
DEN → PHL flights departing 5–9 AM arrived on time 84.1% of the time, against 56.3% for 6–9 PM departures, a gap of 27.8 percentage points.
By departure window
By departure hour
- 12 AM: 64.8% on time from 166 flights
- 1 AM to 5 AM: too few flights to score
- 6 AM: 81.9% on time from 314 flights
- 7 AM: 88.5% on time from 447 flights
- 8 AM: 81.8% on time from 429 flights
- 9 AM: 82.9% on time from 406 flights
- 10 AM: 82.9% on time from 1,263 flights
- 11 AM: 77.5% on time from 424 flights
- 12 PM: 70.9% on time from 974 flights
- 1 PM: 73.2% on time from 661 flights
- 2 PM: 64.5% on time from 488 flights
- 3 PM: too few flights to score
- 4 PM: 49.6% on time from 136 flights
- 5 PM: 66.8% on time from 1,311 flights
- 6 PM: 64.4% on time from 452 flights
- 7 PM: 44.6% on time from 315 flights
- 8 PM to 10 PM: too few flights to score
- 11 PM: 74.0% on time from 1,367 flights
Why DEN → PHL runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for DEN → PHL. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on DEN → PHL, at 42.0%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 84.1% of the time and 6–9 PM departures 56.3%.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| United Airlines | 3,057 | 79.7% | 0.52% | -6 min | 6.8% |
| American Airlines | 2,632 | 77.7% | 1.98% | -8 min | 8.9% |
| Southwest Airlines | 2,456 | 65.8% | 0.61% | 5 min | 10.0% |
| Frontier Airlines | 1,167 | 61.2% | 2.49% | 6 min | 14.9% |
United Airlines flew 32.8% of the 9,312 flights listed. Frontier Airlines cancelled 2.49% of its flights here against 0.52% for United Airlines.
United Airlines arrived on time 18.5 percentage points more often than Frontier Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
Weekly and seasonal patterns
By day of week
Saturday is historically the most reliable day and Thursday the least, a gap of 5.3 percentage points.
By month
- Jan: 77.5%
- Feb: 77.3%
- Mar: 73.6%
- Apr: 78.6%
- May: 69.9%
- Jun: 65.4%
- Jul: 65.4%
- Aug: 70.4%
- Sep: 74.9%
- Oct: 78.5%
- Nov: 80.7%
- Dec: 76.0%
June is historically the weakest month and November the strongest, a spread of 15.3 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 64.2% from 285 flights
- August 2023: 72.8% from 296 flights
- September 2023: 68.2% from 275 flights
- October 2023: 76.0% from 275 flights
- November 2023: 80.9% from 225 flights
- December 2023: 74.7% from 219 flights
- January 2024: 72.3% from 200 flights
- February 2024: 70.1% from 164 flights
- March 2024: 73.5% from 202 flights
- April 2024: 81.3% from 258 flights
- May 2024: 71.3% from 287 flights
- June 2024: 69.8% from 298 flights
- July 2024: 66.1% from 309 flights
- August 2024: 71.1% from 296 flights
- September 2024: 79.6% from 279 flights
- October 2024: 86.3% from 250 flights
- November 2024: 76.5% from 221 flights
- December 2024: 83.4% from 223 flights
- January 2025: 76.9% from 197 flights
- February 2025: 80.3% from 182 flights
- March 2025: 78.8% from 243 flights
- April 2025: 72.9% from 217 flights
- May 2025: 66.4% from 258 flights
- June 2025: 58.9% from 306 flights
- July 2025: 63.1% from 317 flights
- August 2025: 67.6% from 310 flights
- September 2025: 76.6% from 282 flights
- October 2025: 73.5% from 249 flights
- November 2025: 84.5% from 238 flights
- December 2025: 70.0% from 235 flights
- January 2026: 84.0% from 176 flights
- February 2026: 81.2% from 173 flights
- March 2026: 67.5% from 205 flights
- April 2026: 81.0% from 226 flights
- May 2026: 71.5% from 276 flights
- June 2026: 67.5% from 316 flights
- July 2026: 68.0% from 344 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 73.5% against 73.7% in the 12 months before — broadly unchanged.
Data and methodology
Calculated by FlyerIntel from 9,312 DEN → PHL flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed