Carrier route record
ASATL→SEA
Alaska Airlines · Atlanta to Seattle
- Flights
- 906
- Period
- July 2025 to June 2026
- Share of route
- 28%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.
Alaska on ATL 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, 3 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 906 flights, with a median arrival 3 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Alaska on ATL to SEA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
74.3%
Arrivals under 15 minutes late, of 894 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
1.10%
National rate is 1.81%
Whole route
77.8%
Every carrier on ATL to SEA, 3,277 flights
These figures cover 906 flights between July 2025 and June 2026. The median arrival is 3 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 ATL to SEA
Alaska flew 906 of the 3,277 flights on ATL to SEA, about 28% of it. Its 74.3% on time is 4 points worse than the route as a whole, which runs 77.8%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from Delta at 79.1% to Alaska at 74.3%.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 2,371 | 79.1% | 53 min | 0.46% | B+ |
| Alaska Airlines (this page) | 906 | 74.3% | 55 min | 1.10% | C |
Flight by flight
Alaska flight numbers on ATL to SEA
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 29 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am305 flights87.5%
- 8am–11am273 flights72.7%
- 11am–2pm—
- 2pm–5pm67 flights74.2%
- 5pm–8pm228 flights58.4%
- 8pm–5am33 flights72.7%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 58.4% on time, against 87.5% 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 5am–8am window is the busiest, with 305 flights scheduled in it.
Across the year
Alaska on ATL to SEA through the year
December is the weak month at 55.4% on time, against 88.9% 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 92 flights.
Across the week, Saturday is the strongest day at 81.7% on time and Monday the weakest at 67.2%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Alaska 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 13,000 reported delay minutes.
- 35%Late-arriving aircraft
- 31%National Airspace System
- 30%Carrier
- 4%Extreme weather
- 0%Security
35% 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 13,000 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 12,692 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 87.5% on time here.
Cancellations sit at 1.10% against a national 1.81%, which is ordinary. Diversions add another 0.22%.
Connections and stage length
What a delay here costs
6.6% 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 2,182 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 80.3% on time across 905 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.
One caution: this is a thin sample. 906 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 Alaska on ATL to SEA
Put together: treat all of this as provisional. 906 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 74.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 894 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to SEA, every carrier
- Alaska on SEA to ATL, the return leg
- Delta Air Lines on ATL to SEA79.1%
- Alaska Airlines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) 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.