Carrier route record

OOSFO→SEA

SkyWest Airlines · San Francisco to Seattle

Flights: 1,040
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 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, 9 points worse than the national rate of 77.3%. The late ones land about 50 minutes behind schedule. That rests on 1,040 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 986 at 79.5% on time.

Delta Air Lines is the most reliable of the three carriers covered here at 79.5% on time across 986 flights.

On time

68.8%

Arrivals under 15 minutes late, of 1,027 completed flights

Avg delay

50 min

Across delayed arrivals only, not all flights

Cancelled

1.15%

National rate is 1.89%

Whole route

72.3%

Every carrier on SFO to SEA, 6,821 flights

These figures cover 1,040 flights between September 2025 and August 2026. Beyond the headline rate, 8.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Carrier by carrier

SkyWest against every carrier on SFO to SEA

SkyWest flew 1,040 of the 6,821 flights on SFO to SEA, about 15% of it. Its 68.8% on time is 4 points worse than the route as a whole, which runs 72.3%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from Southwest at 100.0% to SkyWest at 68.8%. 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 79.5% of the time; Alaska Airlines manages 68.8%. Sample sizes sit next to every figure, because a two-point gap across 2,729 flights means less than a ten-point one.

On-time performance by carrier on SFO to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlinesthin sample	3	100.0%	—	0.00%	A+
Delta Air Lines	986	79.5%	70 min	1.83%	B
United Airlines	2,063	75.1%	57 min	0.44%	B+
Alaska Airlines	2,729	68.8%	54 min	1.28%	C
SkyWest Airlines (this page)	1,040	68.8%	50 min	1.15%	C

Delta leads Alaska by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

SkyWest flight numbers on SFO to SEA

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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 27 points, against 11 points between the best and worst carrier.

5am–8am71 flights88.4%
8am–11am113 flights73.6%
11am–2pm19 flights—
2pm–5pm212 flights73.9%
5pm–8pm246 flights61.5%
8pm–5am379 flights66.7%

Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 61.5% on time, against 88.4% 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 379 flights scheduled in it.

Across the year

SkyWest on SFO to SEA through the year

Darker means more delays. Figures are on-time percentages.February best, April worst

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 78.6% on time and Thursday the weakest at 56.2%, a spread of 22 points.

Arrival by arrival

How late SkyWest on SFO to SEA runs when it is late

SkyWest on SFO to SEA often beats the schedule: 272 of 1,027 completed flights, 26%, arrived 15 minutes or more early. The 320 late arrivals split 121 under half an hour, 113 between 30 and 60 minutes, and 86 an hour or more.

15+ min early272 flights26.5%
Within 15 min435 flights42.4%
15–29 min late121 flights11.8%
30–59 min late113 flights11.0%
1–2 hours late63 flights6.1%
2+ hours late23 flights2.2%

Scale runs 0% to 100%.

Share of 1,027 completed flights by arrival against schedule.

63 of 313 late departures made up the time and arrived on time, 20% of them. In the other direction, 70 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 SEA.

The worst days

Worst days for SkyWest on SFO to SEA

The latest arrival of the period was on 4 January 2026, 3 hours 58 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.

The latest arrivals of SkyWest on SFO to SEA in the period
Date	Arrived late by	Largest filed cause
4 January 2026	3 hours 58 minutes	Carrier
15 June 2026	3 hours 39 minutes	Carrier
2 April 2026	3 hours 33 minutes	Carrier
28 May 2026	3 hours 30 minutes	National Airspace System
1 January 2026	3 hours 19 minutes	Extreme weather

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 16,000 reported delay minutes.

Carrier
37%
National Airspace System
35%
Extreme weather
22%
Late-arriving aircraft
6%

Extreme weather accounts for 22% 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 3.7 times the usual weather exposure. The split is drawn from 16,030 reported delay minutes.

The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 5,902 of the 16,000 delay minutes reported here.

Cancellations sit at 1.15% against a national 1.89%, which is ordinary. Diversions add another 0.10%.

Connections and stage length

What a delay here costs

8.4% 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 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.

The return leg runs 69.9% on time across 1,039 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. 1,040 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. 1,040 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 68.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,027 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures