Carrier route record
OOSFO→SEA
SkyWest Airlines · San Francisco to Seattle
- Flights
- 1,082
- Period
- July 2025 to June 2026
- Share of route
- 16%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with SkyWest Airlines.
SkyWest on SFO 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, 5 points worse than the national rate of 77.6%. The late ones land about 50 minutes behind schedule. That rests on 1,082 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 924 at 83.6% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 83.6% on time across 924 flights.
Key figures
On time
72.7%
Arrivals under 15 minutes late, of 1,069 completed flights
Avg delay
50 min
Across delayed arrivals only, not all flights
Cancelled
1.11%
National rate is 1.81%
Whole route
73.7%
Every carrier on SFO to SEA, 6,770 flights
These figures cover 1,082 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
SkyWest against every carrier on SFO to SEA
SkyWest flew 1,082 of the 6,770 flights on SFO to SEA, about 16% of it. Its 72.7% on time is about level with the route as a whole at 73.7%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Southwest at 100.0% to Alaska at 69.1%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 83.6% of the time; Alaska Airlines manages 69.1%. Sample sizes sit next to every figure, because a two-point gap across 2,719 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlinesthin sample | 3 | 100.0% | — | 0.00% | A+ |
| Delta Air Lines | 924 | 83.6% | 74 min | 1.73% | B |
| United Airlines | 2,042 | 75.8% | 58 min | 0.39% | B+ |
| SkyWest Airlines (this page) | 1,082 | 72.7% | 50 min | 1.11% | C |
| Alaska Airlines | 2,719 | 69.1% | 53 min | 1.62% | C |
The spread between Delta and Alaska 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.
Flight by flight
SkyWest flight numbers on SFO to SEA
Departure window
When SkyWest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 15 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am77 flights89.3%
- 8am–11am175 flights77.9%
- 11am–2pm33 flights63.6%
- 2pm–5pm268 flights72.6%
- 5pm–8pm183 flights63.5%
- 8pm–5am346 flights72.2%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 63.5% on time, against 89.3% 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 8pm–5am window is the busiest, with 346 flights scheduled in it.
Across the year
SkyWest on SFO to SEA through the year
Delays peak in April, when the on-time rate falls to 47.8%. February is the strongest month at 89.9%. Moving a flexible trip across that boundary buys 42 points. March was the busiest month here, with 108 flights.
Across the week, Saturday is the strongest day at 83.5% on time and Thursday the weakest at 63.9%. 20 points is a smaller lever than departure hour, but it is free.
Delay causes
Why SkyWest 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 15,000 reported delay minutes.
- 38%Carrier
- 37%National Airspace System
- 19%Extreme weather
- 6%Late-arriving aircraft
Extreme weather accounts for 19% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.1 times the usual weather exposure. The split is drawn from 14,626 reported delay minutes.
The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 5,540 of the 15,000 delay minutes reported here.
Cancellations sit at 1.11% against a national 1.81%, which is ordinary. Diversions add another 0.09%.
Connections and stage length
What a delay here costs
6.8% 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 50 minutes, which a normal layover absorbs.
The 679 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 75.4% on time across 1,081 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 1,082 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 SkyWest on SFO to SEA
Put together: treat all of this as provisional. 1,082 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 72.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,069 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to SEA, every carrier
- SkyWest on SEA to SFO, the return leg
- Delta Air Lines on SFO to SEA83.6%
- United Airlines on SFO to SEA75.8%
- Alaska Airlines on SFO to SEA69.1%
- SkyWest Airlines network-wide record
- San Francisco International (SFO) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Same route, different airline: where the carrier you pick matters most
- 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.