Carrier route record
UADEN→PHL
United Airlines · Denver to Philadelphia
- Flights
- 952
- Period
- July 2025 to June 2026
- Share of route
- 32%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on DEN to PHL lands a B+, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 952 flights. The strongest carrier on the route with a full sample, American Airlines, flew 877 at 78.8% on time.
The US average over the same twelve months is 77.6%, so there is little to separate United on DEN to PHL from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.9%
Arrivals under 15 minutes late, of 946 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.53%
National rate is 1.81%
Whole route
73.1%
Every carrier on DEN to PHL, 3,003 flights
These figures cover 952 flights between July 2025 and June 2026. The median arrival is 7 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
United against every carrier on DEN to PHL
United flew 952 of the 3,003 flights on DEN to PHL, about 32% of it. Its 79.9% on time is 7 points better than the route as a whole, which runs 73.1%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 79.9% to Frontier at 62.3%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. American Airlines arrives on time 78.8% of the time; Southwest Airlines manages 63.7%. 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 (this page) | 952 | 79.9% | 66 min | 0.53% | B+ |
| American Airlines | 877 | 78.8% | 103 min | 1.82% | B |
| Southwest Airlines | 879 | 63.7% | 58 min | 0.91% | D+ |
| Frontier Airlinesthin sample | 295 | 62.3% | 103 min | 2.03% | D |
The spread between American 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.
Flight by flight
United flight numbers on DEN to PHL
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 19 points, against 15 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am365 flights86.8%
- 11am–2pm30 flights90.0%
- 2pm–5pm87 flights79.3%
- 5pm–8pm364 flights70.6%
- 8pm–5am106 flights85.7%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 90.0% on time, ahead of 5pm–8pm at 70.6%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 8am–11am window is the busiest, with 365 flights scheduled in it.
Across the year
United on DEN to PHL through the year
July is the worst month at 65.2% on time, 29 points below January, the best at 93.7%. 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. August was the busiest month here, with 93 flights.
Across the week, Tuesday is the strongest day at 83.6% on time and Thursday the weakest at 75.6%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 48% of the 12,000 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
- 28%Carrier
- 23%National Airspace System
- 1%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 12,000 reported delay minutes here, that single category outweighs weather by 48 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 12,444 reported delay minutes.
Cancellations are rare at 0.53%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
6.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
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 83.9% on time across 953 flights, 4 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 4 points of difference.
One caution: this is a thin sample. 952 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 United on DEN to PHL
Put together: treat all of this as provisional. 952 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 79.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 946 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to PHL, every carrier
- United on PHL to DEN, the return leg
- American Airlines on DEN to PHL78.8%
- Southwest Airlines on DEN to PHL63.7%
- Frontier Airlines on DEN to PHL62.3%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- Philadelphia International (PHL) 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.