Carrier route record
ASSEA→SJC
Alaska Airlines · Seattle to San Jose
- Flights
- 1,887
- Period
- September 2025 to August 2026
- Share of route
- 43%
- Carriers
- 6
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Alaska Airlines.
Alaska on SEA to SJC lands a B, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 45 minutes on average. That rests on 1,887 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 1,626 at 85.7% on time.
The US average over the same twelve months is 77.3%, so there is little to separate Alaska on SEA to SJC from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.8%
Arrivals under 15 minutes late, of 1,866 completed flights
Avg delay
44 min
Across delayed arrivals only, not all flights
Cancelled
1.06%
National rate is 1.89%
Whole route
80.1%
Every carrier on SEA to SJC, 4,425 flights
These figures cover 1,887 flights between September 2025 and August 2026. The median arrival is 6 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.
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Carrier by carrier
Alaska against every carrier on SEA to SJC
Alaska flew 1,887 of the 4,425 flights on SEA to SJC, about 43% of it. Its 79.8% on time is about level with the route as a whole at 80.1%. Ranked by on-time rate it is number five of six carriers on the route, where the range runs from United at 100.0% to Southwest at 70.5%. Three 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 85.7% of the time; Southwest Airlines manages 70.5%. Sample sizes sit next to every figure, because a two-point gap across 903 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| Delta Air Linesthin sample | 4 | 100.0% | — | 0.00% | A+ |
| American Airlinesthin sample | 4 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlines | 1,626 | 85.7% | 59 min | 0.18% | A+ |
| Alaska Airlines (this page) | 1,887 | 79.8% | 44 min | 1.06% | B |
| Southwest Airlines | 903 | 70.5% | 46 min | 0.22% | C+ |
The spread between SkyWest and Southwest is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
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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 22 points, against 15 points between the best and worst carrier.
- 5am–8am266 flights94.2%
- 8am–11am208 flights82.0%
- 11am–2pm381 flights77.0%
- 2pm–5pm406 flights78.0%
- 5pm–8pm386 flights78.3%
- 8pm–5am240 flights72.2%
Scale runs 65% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 94.2% of the time, against 72.2% for the overnight window. That is 22 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 406 flights scheduled in it.
Across the year
Alaska on SEA to SJC through the year
August is the worst month at 63.0% on time, 26 points below April, the best at 89.3%. 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 191 flights.
Across the week, Wednesday is the strongest day at 85.6% on time and Friday the weakest at 74.4%, a spread of 11 points.
Arrival by arrival
How late Alaska on SEA to SJC runs when it is late
Alaska on SEA to SJC often beats the schedule: 490 of 1,866 completed flights, 26%, arrived 15 minutes or more early. The 377 late arrivals split 175 under half an hour, 123 between 30 and 60 minutes, and 79 an hour or more.
- 15+ min early490 flights26.3%
- Within 15 min999 flights53.5%
- 15–29 min late175 flights9.4%
- 30–59 min late123 flights6.6%
- 1–2 hours late61 flights3.3%
- 2+ hours late18 flights1.0%
Scale runs 0% to 100%.
Share of 1,866 completed flights by arrival against schedule.
85 of 408 late departures made up the time and arrived on time, 21% of them. 54 flights left on time and still arrived late.
The worst days
Worst days for Alaska on SEA to SJC
The latest arrival of the period was on 13 March 2026, 4 hours 22 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across March, August, January and July, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 March 2026 | 4 hours 22 minutes | Late-arriving aircraft |
| 10 August 2026 | 3 hours 42 minutes | Late-arriving aircraft |
| 12 January 2026 | 3 hours 32 minutes | Carrier |
| 16 July 2026 | 3 hours 18 minutes | Extreme weather |
| 12 July 2026 | 3 hours 8 minutes | Carrier |
Delay causes
Why Alaska runs late on this route
Late-arriving aircraft accounts for 48% of the 17,000 delay minutes carriers reported here, and the remaining four split what is left.
- 48%Late-arriving aircraft
- 38%Carrier
- 12%National Airspace System
- 1%Extreme weather
48% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 17,000 reported delay minutes here, that single category outweighs weather by 35 to one. The split is drawn from 16,629 reported delay minutes.
The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 6,397 of the 17,000 delay minutes reported here.
Cancellations sit at 1.06% against a national 1.89%, which is ordinary. Diversions add another 0.05%.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.3% 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.
The return leg runs 80.7% on time across 1,884 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 1,887 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 SEA to SJC
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 89.3% on time and August 63.0%, a swing of 26 points. If the dates move at all, move them out of August before you think about anything else. 1,866 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to SJC, every carrier
- Alaska on SJC to SEA, the return leg
- SkyWest Airlines on SEA to SJC85.7%
- Southwest Airlines on SEA to SJC70.5%
- Alaska Airlines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- Norman Y. Mineta San Jose International (SJC) 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.