Carrier route record
UAORD→SEA
United Airlines · Chicago to Seattle
- Flights
- 1,535
- 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 ORD to SEA sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,535 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 902 at 68.8% on time.
The national on-time rate over the same period is 77.6%, so United on ORD to SEA runs 4 points behind the country as a whole. Across a thousand flights that is about 40 extra late arrivals.
Key figures
On time
73.6%
Arrivals under 15 minutes late, of 1,522 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
0.72%
National rate is 1.81%
Whole route
68.5%
Every carrier on ORD to SEA, 5,572 flights
These figures cover 1,535 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
United against every carrier on ORD to SEA
United flew 1,535 of the 5,572 flights on ORD to SEA, about 28% of it. Its 73.6% on time is 5 points better than the route as a whole, which runs 68.5%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 73.6% to American at 63.5%.
The three carriers here are closely matched: 5 points 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 |
|---|---|---|---|---|---|
| United Airlines (this page) | 1,535 | 73.6% | 59 min | 0.72% | C+ |
| Delta Air Lines | 902 | 68.8% | 66 min | 1.44% | C |
| Alaska Airlines | 1,799 | 67.5% | 63 min | 1.67% | C |
| American Airlines | 1,336 | 63.5% | 70 min | 2.02% | D |
No carrier stands out. Delta tops the table at 68.8%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
United flight numbers on ORD to SEA
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 33 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am181 flights88.4%
- 8am–11am364 flights83.1%
- 11am–2pm227 flights81.1%
- 2pm–5pm341 flights72.4%
- 5pm–8pm114 flights56.6%
- 8pm–5am308 flights55.3%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 55.3% on time, against 88.4% 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 8am–11am window is the busiest, with 364 flights scheduled in it.
Across the year
United on ORD to SEA through the year
December is the weak month at 50.5% on time, against 86.6% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 185 flights.
The day of the week is close to irrelevant here: 4 points separates the best day from the worst. Weekly demand peaks are not what drives the delays on this operation.
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 24,000 reported delay minutes.
- 42%Late-arriving aircraft
- 28%Carrier
- 23%National Airspace System
- 7%Extreme weather
42% 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 24,000 reported delay minutes here, that single category outweighs weather by 6 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 23,849 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 88.4% on time here.
Cancellations are rare at 0.72%, 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
7.4% 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 1,721 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 79.8% on time across 1,534 flights, 6 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 6 points of difference.
The sample behind these figures is 1,535 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 SEA
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 86.6% on time and December 50.5%, a swing of 36 points. If the dates move at all, move them out of December before you think about anything else. 1,522 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to SEA, every carrier
- United on SEA to ORD, the return leg
- Delta Air Lines on ORD to SEA68.8%
- Alaska Airlines on ORD to SEA67.5%
- American Airlines on ORD to SEA63.5%
- United Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Seattle-Tacoma International (SEA) 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.