Carrier route record

OOONT→SFO

SkyWest Airlines · Ontario to San Francisco

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 ONT to SFO earns an F, which is as low as this site's scale goes for a reason. Only 48.1% of flights arrive inside the 15-minute window, 29 points worse than the national rate of 77.6%. Late arrivals average a little over an hour. Treat any tight connection here as a coin flip. That rests on 106 flights, with a median arrival 17 minutes late.

The national on-time rate over the same period is 77.6%, so SkyWest on ONT to SFO runs 29 points behind the country as a whole. Across a thousand flights that is about 295 extra late arrivals.

On time

48.1%

Arrivals under 15 minutes late, of 104 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

1.89%

National rate is 1.81%

Whole route

64.9%

Every carrier on ONT to SFO, 1,290 flights

These figures cover 106 flights between July 2025 and June 2026. Beyond the headline rate, 21.2% 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 ONT to SFO

SkyWest flew 106 of the 1,290 flights on ONT to SFO, about 8% of it. Its 48.1% on time is 17 points worse than the route as a whole, which runs 64.9%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from United at 70.7% to Frontier at 41.6%. 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 ONT to SFO
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	1,007	70.7%	66 min	0.40%	C+
SkyWest Airlines (this page)thin sample	106	48.1%	68 min	1.89%	F
Frontier Airlinesthin sample	177	41.6%	71 min	2.26%	F

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 ONT to SFO record by time of day without the percentages moving on noise. The headline rate of 48.1% is the reliable figure here.

Across the year

SkyWest on ONT to SFO through the year

Jul–Sep 20258 flights—
Oct–Dec 202529 flights—
Jan–Mar 202624 flights—
Apr–Jun 202645 flights13.6%

Scale runs 5% to 20%. 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 48.1% on time across 106 flights.

Split by quarter, SkyWest on ONT to SFO 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 48.1% annual figure is the one to use.

Delay causes

Why SkyWest runs late on this route

One category carries most of the weight here. National Airspace System accounts for 54% of the 3,674 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
54%
Late-arriving aircraft
22%
Extreme weather
14%
Carrier
10%

Extreme weather accounts for 14% 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 2.2 times the usual weather exposure. The split is drawn from 3,674 reported delay minutes.

54% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,002 minutes out of 3,674, against a national NAS share of 21%.

Cancellations sit at 1.89% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 21.2% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

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 5pm–8pm window matters as much as it does.

The return leg is a different operation and performs like one: it runs 68.9% on time across 106 flights, 21 points above 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 ONT to SFO

Put together: treat all of this as provisional. 106 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 48.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 104 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