Carrier route record
DLORD→SEA
Delta Air Lines · Chicago to Seattle
- Flights
- 902
- Period
- July 2025 to June 2026
- Share of route
- 16%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on ORD to SEA sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 902 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,535 at 73.6% on time.
United Airlines is the most reliable of the three carriers covered here at 73.6% on time across 1,535 flights.
Key figures
On time
68.8%
Arrivals under 15 minutes late, of 884 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
1.44%
National rate is 1.81%
Whole route
68.5%
Every carrier on ORD to SEA, 5,572 flights
These figures cover 902 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
Delta against every carrier on ORD to SEA
Delta flew 902 of the 5,572 flights on ORD to SEA, about 16% of it. Its 68.8% on time is about level with the route as a whole at 68.5%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from United at 73.6% to American at 63.5%.
The choice of carrier is not cosmetic here. United Airlines arrives on time 73.6% of the time; American Airlines manages 63.5%. 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 | 1,535 | 73.6% | 59 min | 0.72% | C+ |
| Delta Air Lines (this page) | 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 |
United leads American by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Delta flight numbers on ORD to SEA
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am347 flights76.5%
- 8am–11am18 flights—
- 11am–2pm136 flights77.9%
- 2pm–5pm175 flights56.2%
- 5pm–8pm226 flights62.4%
- 8pm–5am—
Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 77.9% on time, ahead of 2pm–5pm at 56.2%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 5am–8am window is the busiest, with 347 flights scheduled in it.
Across the year
Delta on ORD to SEA through the year
December is the weak month at 40.0% on time, against 86.1% 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. May was the busiest month here, with 92 flights.
Across the week, Saturday is the strongest day at 76.5% on time and Sunday the weakest at 61.2%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta 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 18,000 reported delay minutes.
- 31%Late-arriving aircraft
- 29%Carrier
- 25%National Airspace System
- 16%Extreme weather
Extreme weather accounts for 16% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.5 times the usual weather exposure. The split is drawn from 18,304 reported delay minutes.
Cancellations sit at 1.44% against a national 1.81%, which is ordinary. Diversions add another 0.55%.
Connections and stage length
What a delay here costs
7.8% 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 77.5% on time across 902 flights, 9 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 9 points of difference.
One caution: this is a thin sample. 902 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking Delta on ORD to SEA
Put together: treat all of this as provisional. 902 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 68.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 884 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to SEA, every carrier
- Delta on SEA to ORD, the return leg
- United Airlines on ORD to SEA73.6%
- Alaska Airlines on ORD to SEA67.5%
- American Airlines on ORD to SEA63.5%
- Delta Air Lines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Same route, different airline: where the carrier you pick matters most
- 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.