Carrier route record
UASEA→ORD
United Airlines · Seattle to Chicago
- Flights
- 1,534
- Period
- July 2025 to June 2026
- Share of route
- 28%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on SEA to ORD 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 a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,534 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 902 at 77.5% on time.
The US average over the same twelve months is 77.6%, so there is little to separate United on SEA to ORD from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.8%
Arrivals under 15 minutes late, of 1,511 completed flights
Avg delay
81 min
Across delayed arrivals only, not all flights
Cancelled
0.91%
National rate is 1.81%
Whole route
75.0%
Every carrier on SEA to ORD, 5,566 flights
These figures cover 1,534 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 SEA to ORD
United flew 1,534 of the 5,566 flights on SEA to ORD, about 28% of it. Its 79.8% on time is 5 points better than the route as a whole, which runs 75.0%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 79.8% to American at 71.2%.
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 77.5% of the time; American Airlines manages 71.2%. Sample sizes sit next to every figure, because a two-point gap across 1,336 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 1,534 | 79.8% | 81 min | 0.91% | B+ |
| Delta Air Lines | 902 | 77.5% | 71 min | 1.22% | B |
| Alaska Airlines | 1,794 | 72.3% | 55 min | 1.06% | C |
| American Airlines | 1,336 | 71.2% | 93 min | 2.02% | C |
Delta leads American by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
United flight numbers on SEA to ORD
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 27 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am365 flights90.9%
- 8am–11am79 flights79.2%
- 11am–2pm325 flights78.1%
- 2pm–5pm257 flights63.6%
- 5pm–8pm118 flights81.4%
- 8pm–5am390 flights81.2%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.9% of the time, against 63.6% for the afternoon window. That is 27 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 390 flights scheduled in it.
Across the year
United on SEA to ORD through the year
August is the worst month at 68.5% on time, 27 points below February, the best at 95.1%. 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. July was the busiest month here, with 185 flights.
Across the week, Tuesday is the strongest day at 85.0% on time and Friday the weakest at 74.5%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
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 25,000 reported delay minutes.
- 40%National Airspace System
- 30%Carrier
- 27%Late-arriving aircraft
- 2%Extreme weather
40% 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 9,991 minutes out of 25,000, against a national NAS share of 21%. The split is drawn from 24,724 reported delay minutes.
Cancellations sit at 0.91% against a national 1.81%, which is ordinary. Diversions add another 0.59%.
Connections and stage length
What a delay here costs
7.5% 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 a little over an hour, which a normal layover absorbs.
At 1,721 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 73.6% on time across 1,535 flights, 6 points below 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 6 points of difference.
The sample behind these figures is 1,534 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 SEA to ORD
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 95.1% on time and August 68.5%, a swing of 27 points. If the dates move at all, move them out of August before you think about anything else. 1,511 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to ORD, every carrier
- United on ORD to SEA, the return leg
- Delta Air Lines on SEA to ORD77.5%
- Alaska Airlines on SEA to ORD72.3%
- American Airlines on SEA to ORD71.2%
- United Airlines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
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.