Carrier route record

OOSFO→ONT

SkyWest Airlines · San Francisco to Ontario

Flights: 106
Period: July 2025 to June 2026
Share of route: 8%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with SkyWest Airlines.

SkyWest on SFO to ONT 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 77.6%. The late ones land a little over an hour behind schedule. That rests on 106 flights, with a median arrival right on schedule.

The national on-time rate over the same period is 77.6%, so SkyWest on SFO to ONT runs 9 points behind the country as a whole. Across a thousand flights that is about 87 extra late arrivals.

On time

68.9%

Arrivals under 15 minutes late, of 103 completed flights

Avg delay

77 min

Across delayed arrivals only, not all flights

Cancelled

2.83%

National rate is 1.81%

Whole route

76.8%

Every carrier on SFO to ONT, 1,291 flights

These figures cover 106 flights between July 2025 and June 2026. Beyond the headline rate, 8.7% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

SkyWest against every carrier on SFO to ONT

SkyWest flew 106 of the 1,291 flights on SFO to ONT, about 8% of it. Its 68.9% on time is 8 points worse than the route as a whole, which runs 76.8%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from United at 81.0% to Frontier at 56.7%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on SFO to ONT
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	1,008	81.0%	55 min	0.30%	B+
SkyWest Airlines (this page)thin sample	106	68.9%	77 min	2.83%	C
Frontier Airlinesthin sample	177	56.7%	107 min	3.39%	D−

Departure window

When SkyWest runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 106 flights.

There are not enough flights in each departure window to split SkyWest's SFO to ONT record by time of day without the percentages moving on noise. The headline rate of 68.9% is the reliable figure here.

Across the year

SkyWest on SFO to ONT through the year

Jul–Sep 20258 flights—
Oct–Dec 202529 flights—
Jan–Mar 202624 flights—
Apr–Jun 202645 flights68.2%

Scale runs 60% to 75%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 68.9% on time across 106 flights.

Split by quarter, SkyWest on SFO to ONT logged 8 flights in Jul–Sep 2025, 29 flights in Oct–Dec 2025, 24 flights in Jan–Mar 2026 and 45 flights in Apr–Jun 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 68.9% annual figure is the one to use.

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 2,468 reported delay minutes.

Late-arriving aircraft
42%
National Airspace System
24%
Extreme weather
22%
Carrier
12%

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 3.6 times the usual weather exposure. The split is drawn from 2,468 reported delay minutes.

42% 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 2,468 reported delay minutes here, that single category outweighs weather by 2 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.

Cancellations run at 2.83%, against 1.81% nationally. That is roughly one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and stage length

What a delay here costs

8.7% 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 a little over an hour, which a normal layover absorbs.

At 363 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 2pm–5pm window matters as much as it does.

The return leg is a different operation and performs like one: it runs 48.1% on time across 106 flights, 21 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 21 points of difference.

One caution: this is a thin sample. 106 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 ONT

Put together: the delay figures matter less here than the 2.83% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 2pm–5pm departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 103 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures