Carrier route record
ASSEA→ORD
Alaska Airlines · Seattle to Chicago
- Flights
- 1,794
- 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 Alaska Airlines.
Alaska on SEA to ORD 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 about an hour behind schedule. That rests on 1,794 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,534 at 79.8% on time.
United Airlines is the most reliable of the three carriers covered here at 79.8% on time across 1,534 flights.
Key figures
On time
72.3%
Arrivals under 15 minutes late, of 1,761 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
1.06%
National rate is 1.81%
Whole route
75.0%
Every carrier on SEA to ORD, 5,566 flights
These figures cover 1,794 flights between July 2025 and June 2026. The median arrival is 2 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
Alaska against every carrier on SEA to ORD
Alaska flew 1,794 of the 5,566 flights on SEA to ORD, about 32% of it. Its 72.3% on time is 3 points worse than the route as a whole, which runs 75.0%. Ranked by on-time rate it is number three 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. United Airlines arrives on time 79.8% 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 | 1,534 | 79.8% | 81 min | 0.91% | B+ |
| Delta Air Lines | 902 | 77.5% | 71 min | 1.22% | B |
| Alaska Airlines (this page) | 1,794 | 72.3% | 55 min | 1.06% | C |
| American Airlines | 1,336 | 71.2% | 93 min | 2.02% | C |
United leads American by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Alaska flight numbers on SEA to ORD
Departure window
When Alaska runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 31 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am112 flights88.3%
- 8am–11am552 flights68.5%
- 11am–2pm326 flights57.6%
- 2pm–5pm178 flights75.1%
- 5pm–8pm362 flights77.7%
- 8pm–5am264 flights82.3%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 57.6% on time against 88.3% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8am–11am window is the busiest, with 552 flights scheduled in it.
Across the year
Alaska on SEA to ORD through the year
August is the worst month at 54.4% on time, 40 points below February, the best at 94.4%. 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 211 flights.
Across the week, Tuesday is the strongest day at 81.8% on time and Sunday the weakest at 64.7%. 17 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Alaska runs late on this route
One category carries most of the weight here. National Airspace System accounts for 45% of the 27,000 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.
- 45%National Airspace System
- 31%Carrier
- 22%Late-arriving aircraft
- 2%Extreme weather
- 0%Security
45% 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 12,000 minutes out of 27,000, against a national NAS share of 21%. The split is drawn from 26,798 reported delay minutes.
Cancellations sit at 1.06% against a national 1.81%, which is ordinary. Diversions add another 0.78%.
Connections and stage length
What a delay here costs
7.2% 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 67.5% on time across 1,799 flights, 5 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 5 points of difference.
The sample behind these figures is 1,794 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 Alaska on SEA to ORD
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 94.4% on time and August 54.4%, a swing of 40 points. If the dates move at all, move them out of August before you think about anything else. 1,761 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to ORD, every carrier
- Alaska on ORD to SEA, the return leg
- United Airlines on SEA to ORD79.8%
- Delta Air Lines on SEA to ORD77.5%
- American Airlines on SEA to ORD71.2%
- Alaska 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.