Carrier route record
UAORD→PHL
United Airlines · Chicago to Philadelphia
- Flights
- 1,776
- Period
- July 2025 to June 2026
- Share of route
- 36%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on ORD to PHL sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 1,776 flights, with a median arrival 3 minutes early.
The national on-time rate over the same period is 77.6%, so United on ORD to PHL runs 5 points behind the country as a whole. Across a thousand flights that is about 54 extra late arrivals.
Key figures
On time
72.2%
Arrivals under 15 minutes late, of 1,750 completed flights
Avg delay
78 min
Across delayed arrivals only, not all flights
Cancelled
1.30%
National rate is 1.81%
Whole route
71.2%
Every carrier on ORD to PHL, 4,918 flights
These figures cover 1,776 flights between July 2025 and June 2026. Beyond the headline rate, 11.7% 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
United against every carrier on ORD to PHL
United flew 1,776 of the 4,918 flights on ORD to PHL, about 36% of it. Its 72.2% on time is about level with the route as a whole at 71.2%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from Republic at 81.5% to Frontier at 60.4%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 27 | 81.5% | 46 min | 0.00% | B+ |
| United Airlines (this page) | 1,776 | 72.2% | 78 min | 1.30% | C |
| American Airlines | 2,926 | 71.1% | 100 min | 3.76% | C− |
| Frontier Airlinesthin sample | 189 | 60.4% | 139 min | 3.70% | D− |
Flight by flight
United flight numbers on ORD 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 30 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am213 flights88.6%
- 8am–11am184 flights82.5%
- 11am–2pm365 flights78.2%
- 2pm–5pm392 flights68.6%
- 5pm–8pm364 flights58.3%
- 8pm–5am258 flights67.9%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 58.3% on time, against 88.6% 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 2pm–5pm window is the busiest, with 392 flights scheduled in it.
Across the year
United on ORD to PHL through the year
July is the worst month at 53.5% on time, 28 points below October, the best at 81.3%. 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 197 flights.
Across the week, Tuesday is the strongest day at 78.0% on time and Monday the weakest at 67.6%. 10 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 47% of the 38,000 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.
- 47%Late-arriving aircraft
- 24%Carrier
- 23%National Airspace System
- 6%Extreme weather
47% 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 38,000 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 37,919 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 88.6% on time here.
Cancellations sit at 1.30% against a national 1.81%, which is ordinary. Diversions add another 0.17%.
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. 11.7% 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 678 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 runs 74.0% on time across 1,773 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 1,776 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking United on ORD to PHL
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 81.3% on time and July 53.5%, a swing of 28 points. If the dates move at all, move them out of July before you think about anything else. 1,750 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to PHL, every carrier
- United on PHL to ORD, the return leg
- American Airlines on ORD to PHL71.1%
- Frontier Airlines on ORD to PHL60.4%
- United Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Philadelphia International (PHL) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.