Carrier route record
ASSJC→SEA
Alaska Airlines · San Jose to Seattle
- Flights
- 1,874
- Period
- July 2025 to June 2026
- Share of route
- 43%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.
Alaska on SJC to SEA lands a B, 4 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about 50 minutes on average. That is a workable record, not a spotless one. That rests on 1,874 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 1,563 at 89.5% on time.
Set against the rest of the country, Alaska's SJC to SEA record is 4 points better than the US average of 77.6%. That gap is worth roughly 44 fewer late arrivals for every thousand flights.
Key figures
On time
82.0%
Arrivals under 15 minutes late, of 1,843 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
1.65%
National rate is 1.81%
Whole route
83.3%
Every carrier on SJC to SEA, 4,368 flights
These figures cover 1,874 flights between July 2025 and June 2026. The median arrival is 7 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 SJC to SEA
Alaska flew 1,874 of the 4,368 flights on SJC to SEA, about 43% of it. Its 82.0% on time is about level with the route as a whole at 83.3%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from American at 100.0% to Southwest at 75.6%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 89.5% of the time; Southwest Airlines manages 75.6%. Sample sizes sit next to every figure, because a two-point gap across 928 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| American Airlinesthin sample | 2 | 100.0% | — | 0.00% | A+ |
| United Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlines | 1,563 | 89.5% | 66 min | 0.19% | A+ |
| Alaska Airlines (this page) | 1,874 | 82.0% | 49 min | 1.65% | B |
| Southwest Airlines | 928 | 75.6% | 45 min | 0.00% | B+ |
The spread between SkyWest and Southwest is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 more arrivals inside the on-time window.
Flight by flight
Alaska flight numbers on SJC 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 18 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am189 flights93.1%
- 8am–11am509 flights80.2%
- 11am–2pm272 flights89.6%
- 2pm–5pm375 flights80.0%
- 5pm–8pm450 flights77.4%
- 8pm–5am79 flights75.0%
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.1% of the time, against 75.0% for the overnight window. That is 18 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 509 flights scheduled in it.
Across the year
Alaska on SJC to SEA through the year
June is the worst month at 67.5% on time, 28 points below February, the best at 95.5%. 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 187 flights.
Across the week, Wednesday is the strongest day at 87.8% on time and Thursday the weakest at 77.2%. 11 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 16,000 reported delay minutes.
- 40%Late-arriving aircraft
- 33%National Airspace System
- 23%Carrier
- 4%Extreme weather
- 0%Security
40% 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 16,000 reported delay minutes here, that single category outweighs weather by 11 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 16,306 reported delay minutes.
33% 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 5,322 minutes out of 16,000, against a national NAS share of 21%.
Cancellations sit at 1.65% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 3.9% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 696 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 80.6% on time across 1,877 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 1,874 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 SJC to SEA
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 95.5% on time and June 67.5%, a swing of 28 points. If the dates move at all, move them out of June before you think about anything else. 1,843 completed flights over 12 months sit behind that.
Related
Where to go next
- SJC to SEA, every carrier
- Alaska on SEA to SJC, the return leg
- SkyWest Airlines on SJC to SEA89.5%
- Southwest Airlines on SJC to SEA75.6%
- Alaska Airlines network-wide record
- Norman Y. Mineta San Jose International (SJC) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.