Carrier route record
ASRDU→SEA
Alaska Airlines · Raleigh to Seattle
- Flights
- 555
- Period
- July 2025 to June 2026
- Share of route
- 60%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.
Alaska on RDU 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, 7 points worse than the national rate of 77.6%. The late ones land roughly 45 minutes behind schedule. That rests on 555 flights, with a median arrival right on schedule.
The national on-time rate over the same period is 77.6%, so Alaska on RDU to SEA runs 7 points behind the country as a whole. Across a thousand flights that is about 65 extra late arrivals.
Key figures
On time
71.1%
Arrivals under 15 minutes late, of 544 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
1.62%
National rate is 1.81%
Whole route
75.9%
Every carrier on RDU to SEA, 919 flights
These figures cover 555 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
Alaska against every carrier on RDU to SEA
Alaska flew 555 of the 919 flights on RDU to SEA, most of the route. Its 71.1% on time is 5 points worse than the route as a whole, which runs 75.9%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from Delta at 83.1% to Alaska at 71.1%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 Linesthin sample | 364 | 83.1% | 49 min | 1.37% | B |
| Alaska Airlines (this page) | 555 | 71.1% | 47 min | 1.62% | C |
Flight by flight
Alaska flight numbers on RDU to SEA
Departure window
When Alaska runs best on this route
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 555 flights.
- 5am–8am224 flights75.9%
- 8am–11am—
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm331 flights67.9%
- 8pm–5am—
Scale runs 60% to 80%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 75.9% of the time, against 67.9% for the evening window. That is 8 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 331 flights scheduled in it.
Across the year
Alaska on RDU to SEA through the year
December is the weak month at 40.5% on time, against 91.1% 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 62 flights.
Across the week, Sunday is the strongest day at 78.8% on time and Monday the weakest at 62.7%. 16 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 7,344 reported delay minutes.
- 37%Late-arriving aircraft
- 31%National Airspace System
- 27%Carrier
- 4%Extreme weather
- 2%Security
37% 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 7,344 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 7,344 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 75.9% on time here.
Cancellations sit at 1.62% against a national 1.81%, which is ordinary. Diversions add another 0.36%.
Connections and stage length
What a delay here costs
5.1% 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 45 minutes, which a normal layover absorbs.
At 2,354 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 555 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. 555 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 RDU to SEA
Put together: treat all of this as provisional. 555 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 71.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 544 completed flights over 12 months sit behind that.
Related
Where to go next
- RDU to SEA, every carrier
- Alaska on SEA to RDU, the return leg
- Delta Air Lines on RDU to SEA83.1%
- Alaska Airlines network-wide record
- Raleigh-Durham International (RDU) 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.