Route reliability record
PHL→ORD
Philadelphia to Chicago
- Flights
- 4,911
- Period
- July 2025 to June 2026
- Distance
- 678 mi
- Carriers
- 4
This route sits in the middle of the pack with a C−. Close to three flights in four arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 4,911 flights, of which United Airlines flew 1,773 at 74.0% on time.
The national on-time rate over the same period is 77.6%, so this route runs 5 points behind the country as a whole. Across a thousand flights that is about 46 extra late arrivals.
Key figures
On time
73.0%
Arrivals under 15 minutes late, of 4,735 completed flights
Avg delay
99 min
Across delayed arrivals only, not all flights
Cancelled
3.12%
National rate is 1.81%
Best carrier
United
74.0% on time across 1,773 flights
These figures cover 4,911 flights between July 2025 and June 2026. Beyond the headline rate, 11.8% 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
Which airline is most reliable on PHL to ORD
The two carriers here are closely matched: about a point separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 26 | 92.3% | 44 min | 0.00% | A+ |
| United Airlines | 1,773 | 74.0% | 94 min | 1.75% | C |
| American Airlines | 2,923 | 73.2% | 98 min | 3.90% | C− |
| Frontier Airlinesthin sample | 189 | 58.6% | 137 min | 4.23% | D− |
American Airlines cancels 3.9% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 29 points, against about a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am874 flights86.3%
- 8am–11am1,077 flights80.6%
- 11am–2pm913 flights77.6%
- 2pm–5pm626 flights68.3%
- 5pm–8pm1,138 flights56.9%
- 8pm–5am283 flights62.5%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 56.9% on time, against 86.3% 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 5pm–8pm window is the busiest, with 1,138 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 22 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 60.2% on time, 22 points below February, the best at 82.3%. 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. May was the busiest month here, with 492 flights.
Across the week, Tuesday is the strongest day at 78.9% on time and Sunday the weakest at 65.9%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 127,000 reported delay minutes.
- 37%Late-arriving aircraft
- 37%National Airspace System
- 22%Carrier
- 4%Extreme weather
- 0%Security
37% 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 127,000 reported delay minutes here, that single category outweighs weather by 10 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 126,609 reported delay minutes.
37% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 47,000 minutes out of 127,000, against a national NAS share of 21%.
Cancellations run at 3.12%, against 1.81% nationally. That is about one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.8% 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 71.2% on time across 4,918 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 4,911 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 this route
Put together: the delay figures matter less here than the 3.12% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 4,735 completed flights over 12 months sit behind that.
Common questions
PHL to ORD questions
How often is PHL to ORD delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.0% of the 4,911 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on PHL to ORD?
United Airlines leads at 74.0% on time across 1,773 flights. American Airlines is at the other end on 73.2%, a gap of about a point. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on PHL to ORD?
The 5am–8am departure window is the strongest at 86.3% on time. The 5pm–8pm window is the weakest at 56.9%, 29 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on PHL to ORD?
July is the weakest month at 60.2% on time, compared with 82.3% in February. Across the year that is 22 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ORD to PHL — the return legseparate record
- Philadelphia International (PHL) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- Republic Airways on-time record92.3%
- United Airlines on-time record74.0%
- American Airlines on-time record73.2%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. PHL to ORD and ORD to PHL are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.