Carrier route record
OOSEA→SFO
SkyWest Airlines · Seattle to San Francisco
- Flights
- 1,039
- Period
- September 2025 to August 2026
- Share of route
- 15%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with SkyWest Airlines.
SkyWest on SEA to SFO 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 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 1,039 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 985 at 60.5% on time.
The national on-time rate over the same period is 77.3%, so SkyWest on SEA to SFO runs 7 points behind the country as a whole. Across a thousand flights that is about 74 extra late arrivals.
Key figures
On time
69.9%
Arrivals under 15 minutes late, of 1,028 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
1.06%
National rate is 1.89%
Whole route
59.8%
Every carrier on SEA to SFO, 6,817 flights
These figures cover 1,039 flights between September 2025 and August 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.
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Carrier by carrier
SkyWest against every carrier on SEA to SFO
SkyWest flew 1,039 of the 6,817 flights on SEA to SFO, about 15% of it. Its 69.9% on time is 10 points better than the route as a whole, which runs 59.8%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from Southwest at 100.0% to Alaska at 56.0%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The three carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlinesthin sample | 4 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlines (this page) | 1,039 | 69.9% | 52 min | 1.06% | C |
| Delta Air Lines | 985 | 60.5% | 54 min | 1.73% | D |
| United Airlines | 2,062 | 59.1% | 67 min | 0.82% | D+ |
| Alaska Airlines | 2,727 | 56.0% | 52 min | 1.14% | D |
No carrier stands out. Delta tops the table at 60.5%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
SkyWest flight numbers on SEA to SFO
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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 34 points, against 5 points between the best and worst carrier.
- 5am–8am313 flights85.4%
- 8am–11am31 flights51.6%
- 11am–2pm210 flights75.2%
- 2pm–5pm244 flights62.0%
- 5pm–8pm238 flights56.1%
- 8pm–5am3 flights—
Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 85.4% of the time, against 51.6% for the morning window. That is 34 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 313 flights scheduled in it.
Across the year
SkyWest on SEA to SFO through the year
June is the worst month at 49.0% on time, 37 points below March, the best at 86.0%. 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. March was the busiest month here, with 109 flights.
Across the week, Saturday is the strongest day at 76.6% on time and Thursday the weakest at 65.5%, a spread of 11 points.
Arrival by arrival
How late SkyWest on SEA to SFO runs when it is late
The 309 late arrivals split 121 under half an hour, 109 between 30 and 60 minutes, and 79 an hour or more.
- 15+ min early233 flights22.7%
- Within 15 min486 flights47.3%
- 15–29 min late121 flights11.8%
- 30–59 min late109 flights10.6%
- 1–2 hours late58 flights5.6%
- 2+ hours late21 flights2.0%
Scale runs 0% to 100%.
Share of 1,028 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 222 departures that left 15 minutes late or more, only 25 made it up before arrival. In the other direction, 112 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SFO.
The worst days
Worst days for SkyWest on SEA to SFO
The latest arrival of the period was on 13 March 2026, 8 hours 3 minutes behind schedule; most of its delay minutes were filed as extreme weather. On three of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 March 2026 | 8 hours 3 minutes | Extreme weather |
| 15 June 2026 | 4 hours 13 minutes | Carrier |
| 2 January 2026 | 4 hours 5 minutes | National Airspace System |
| 4 January 2026 | 3 hours 51 minutes | Carrier |
| 21 July 2026 | 3 hours 38 minutes | Carrier |
Delay causes
Why SkyWest runs late on this route
National Airspace System accounts for 47% of the 16,000 delay minutes carriers reported here, and the remaining four split what is left.
- 47%National Airspace System
- 40%Carrier
- 13%Extreme weather
- 1%Late-arriving aircraft
- 0%Security
Extreme weather accounts for 13% 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 2.1 times the usual weather exposure. The split is drawn from 15,946 reported delay minutes.
The largest share of delay minutes, 40%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 6,358 of the 16,000 delay minutes reported here.
Cancellations sit at 1.06% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
7.7% of arrivals land an hour or more late, close to the national 8.3%, so 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.
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.
The return leg runs 68.8% on time across 1,040 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.
One caution: this is a thin sample. 1,039 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 SEA to SFO
Put together: treat all of this as provisional. 1,039 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 69.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,028 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to SFO, every carrier
- SkyWest on SFO to SEA, the return leg
- Delta Air Lines on SEA to SFO60.5%
- United Airlines on SEA to SFO59.1%
- Alaska Airlines on SEA to SFO56.0%
- SkyWest Airlines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- San Francisco International (SFO) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
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.