Carrier route record
F9SFO→SLC
Frontier Airlines · San Francisco to Salt Lake City
- 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 SFO to SLC sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 178 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 1,708 at 78.1% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 78.1% on time across 1,708 flights.
Key figures
On time
69.9%
Arrivals under 15 minutes late, of 176 completed flights
Avg delay
82 min
Across delayed arrivals only, not all flights
Cancelled
1.12%
National rate is 1.81%
Whole route
77.2%
Every carrier on SFO to SLC, 3,471 flights
These figures cover 178 flights between July 2025 and June 2026. Beyond the headline rate, 13.6% 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 SFO to SLC
Frontier flew 178 of the 3,471 flights on SFO to SLC, about 5% of it. Its 69.9% on time is 7 points worse than the route as a whole, which runs 77.2%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from Delta at 78.1% to Frontier at 69.9%.
The three carriers here are closely matched: about a point 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 1,708 | 78.1% | 77 min | 0.88% | B+ |
| SkyWest Airlines | 1,103 | 77.2% | 63 min | 1.18% | B |
| United Airlines | 482 | 76.7% | 55 min | 0.21% | B+ |
| Frontier Airlines (this page)thin sample | 178 | 69.9% | 82 min | 1.12% | C |
No carrier stands out. Delta tops the table at 78.1%, about a point clear of the bottom, which is inside the range this kind of sample moves year to year.
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 29 points, against about a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am33 flights84.8%
- 11am–2pm11 flights—
- 2pm–5pm37 flights55.6%
- 5pm–8pm97 flights75.0%
- 8pm–5am—
Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 84.8% of the time, against 55.6% for the afternoon window. That is 29 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 97 flights scheduled in it.
Across the year
Frontier on SFO to SLC through the year
- Jul–Sep 202545 flights68.9%
- Oct–Dec 202537 flights58.3%
- Jan–Mar 202633 flights81.8%
- Apr–Jun 202663 flights71.0%
Scale runs 50% to 85%. 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 69.9% on time across 178 flights.
Frontier on SFO to SLC did not run the same all year. Its best quarter was Jan–Mar 2026 at 81.8% on time and its weakest Oct–Dec 2025 at 58.3%, a swing of 24 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.
Delay causes
Why Frontier runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 65% of the 4,369 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.
- 65%Late-arriving aircraft
- 24%Carrier
- 11%National Airspace System
- 0%Extreme weather
65% 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 4,369 reported delay minutes here, that single category outweighs weather by 65 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 4,369 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 84.8% on time here.
Cancellations sit at 1.12% 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. 13.6% 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 66.3% on time across 178 flights, 4 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 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 SFO to SLC
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 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. 176 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to SLC, every carrier
- Frontier on SLC to SFO, the return leg
- Delta Air Lines on SFO to SLC78.1%
- SkyWest Airlines on SFO to SLC77.2%
- United Airlines on SFO to SLC76.7%
- Frontier Airlines network-wide record
- San Francisco International (SFO) delay statistics
- Salt Lake City International (SLC) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.