Carrier route record
ASDTW→SEA
Alaska Airlines · Detroit to Seattle
- Flights
- 541
- Period
- July 2025 to June 2026
- Share of route
- 26%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.
Alaska on DTW 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 roughly 50 minutes behind schedule. That rests on 541 flights, with a median arrival 2 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Alaska on DTW 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
74.9%
Arrivals under 15 minutes late, of 538 completed flights
Avg delay
48 min
Across delayed arrivals only, not all flights
Cancelled
0.37%
National rate is 1.81%
Whole route
73.2%
Every carrier on DTW to SEA, 2,076 flights
These figures cover 541 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 DTW to SEA
Alaska flew 541 of the 2,076 flights on DTW to SEA, about 26% of it. Its 74.9% on time is 2 points better than the route as a whole, which runs 73.2%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Alaska at 74.9% to Delta at 72.6%.
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 |
|---|---|---|---|---|---|
| Alaska Airlines (this page) | 541 | 74.9% | 48 min | 0.37% | C+ |
| Delta Air Lines | 1,535 | 72.6% | 55 min | 1.04% | C |
Flight by flight
Alaska flight numbers on DTW 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 15 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–8am195 flights77.3%
- 8am–11am—
- 11am–2pm1 flights—
- 2pm–5pm43 flights62.8%
- 5pm–8pm302 flights75.0%
- 8pm–5am—
Scale runs 55% to 85%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 77.3% of the time, against 62.8% for the afternoon window. That is 15 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 302 flights scheduled in it.
Across the year
Alaska on DTW to SEA through the year
December is the weak month at 35.0% on time, against 92.3% in April. 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 62 flights.
Across the week, Saturday is the strongest day at 81.8% on time and Sunday the weakest at 68.4%. 13 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. Late-arriving aircraft accounts for 48% of the 6,459 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.
- 48%Late-arriving aircraft
- 28%National Airspace System
- 18%Carrier
- 5%Extreme weather
- 1%Security
48% 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 6,459 reported delay minutes here, that single category outweighs weather by 9 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 6,459 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 77.3% on time here.
Cancellations are rare at 0.37%, 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
5.9% 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 roughly 50 minutes, which a normal layover absorbs.
At 1,927 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 83.1% on time across 540 flights, 8 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 8 points of difference.
One caution: this is a thin sample. 541 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 DTW to SEA
Put together: treat all of this as provisional. 541 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 74.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 538 completed flights over 12 months sit behind that.
Related
Where to go next
- DTW to SEA, every carrier
- Alaska on SEA to DTW, the return leg
- Delta Air Lines on DTW to SEA72.6%
- Alaska Airlines network-wide record
- Detroit Metropolitan Wayne County (DTW) 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.