Carrier route record

F9SLC→SFO

Frontier Airlines · Salt Lake City to San Francisco

Flights: 178
Period: July 2025 to June 2026
Share of route: 5%
Carriers: 4

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

Frontier on SLC to SFO draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 178 flights. The strongest carrier on the route with a full sample, United Airlines, flew 484 at 76.6% on time.

United Airlines is the most reliable of the three carriers covered here at 76.6% on time across 484 flights.

On time

66.3%

Arrivals under 15 minutes late, of 175 completed flights

Avg delay

95 min

Across delayed arrivals only, not all flights

Cancelled

1.69%

National rate is 1.81%

Whole route

69.0%

Every carrier on SLC to SFO, 3,472 flights

These figures cover 178 flights between July 2025 and June 2026. Beyond the headline rate, 16.0% 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

Frontier against every carrier on SLC to SFO

Frontier flew 178 of the 3,472 flights on SLC to SFO, about 5% of it. Its 66.3% on time is 3 points worse than the route as a whole, which runs 69.0%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from United at 76.6% to Frontier at 66.3%.

The choice of carrier is not cosmetic here. United Airlines arrives on time 76.6% of the time; Delta Air Lines manages 67.4%. Sample sizes sit next to every figure, because a two-point gap across 1,706 flights means less than a ten-point one.

On-time performance by carrier on SLC to SFO
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	484	76.6%	72 min	0.21%	B+
SkyWest Airlines	1,104	68.8%	76 min	1.27%	C
Delta Air Lines	1,706	67.4%	52 min	0.88%	C+
Frontier Airlines (this page)thin sample	178	66.3%	95 min	1.69%	C

United leads Delta by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Frontier runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am4 flights—
11am–2pm22 flights—
2pm–5pm78 flights68.8%
5pm–8pm29 flights—
8pm–5am45 flights47.7%

Scale runs 40% to 75%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 47.7% on time, against 68.8% for the 2pm–5pm 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 2pm–5pm window is the busiest, with 78 flights scheduled in it.

Across the year

Frontier on SLC to SFO through the year

Jul–Sep 202545 flights64.4%
Oct–Dec 202537 flights72.2%
Jan–Mar 202633 flights75.8%
Apr–Jun 202663 flights59.0%

Scale runs 50% to 80%. 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 66.3% on time across 178 flights.

Frontier on SLC to SFO did not run the same all year. Its best quarter was Jan–Mar 2026 at 75.8% on time and its weakest Apr–Jun 2026 at 59.0%, a swing of 17 points on roughly 45 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Friday is the strongest day at 69.2% on time and Sunday the weakest at 60.0%. 9 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 47% of the 5,614 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.

Late-arriving aircraft
47%
National Airspace System
27%
Carrier
24%
Extreme weather
1%

47% 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 5,614 reported delay minutes here, that single category outweighs weather by 39 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. The split is drawn from 5,614 reported delay minutes.

Cancellations sit at 1.69% 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. 16.0% 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.

The 599 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 is a different operation and performs like one: it runs 69.9% on time across 178 flights, 4 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 4 points of difference.

One caution: this is a thin sample. 178 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 Frontier on SLC to SFO

Put together: treat all of this as provisional. 178 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 66.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 175 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