Carrier route record
DLSFO→SLC
Delta Air Lines · San Francisco to Salt Lake City
- Flights
- 1,708
- Period
- July 2025 to June 2026
- Share of route
- 49%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on SFO to SLC lands a B+, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,708 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 1,103 at 77.2% on time.
The US average over the same twelve months is 77.6%, so there is little to separate Delta on SFO to SLC from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.1%
Arrivals under 15 minutes late, of 1,693 completed flights
Avg delay
77 min
Across delayed arrivals only, not all flights
Cancelled
0.88%
National rate is 1.81%
Whole route
77.2%
Every carrier on SFO to SLC, 3,471 flights
These figures cover 1,708 flights between July 2025 and June 2026. The median arrival is 8 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Delta against every carrier on SFO to SLC
Delta flew 1,708 of the 3,471 flights on SFO to SLC, about 49% of it. Its 78.1% on time is about level with the route as a whole at 77.2%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from Delta at 78.1% to Frontier at 69.9%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: half 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 (this page) | 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 Airlinesthin sample | 178 | 69.9% | 82 min | 1.12% | C |
No carrier stands out. SkyWest tops the table at 77.2%, half a point clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Delta flight numbers on SFO to SLC
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 30 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am365 flights96.7%
- 8am–11am361 flights78.1%
- 11am–2pm366 flights66.6%
- 2pm–5pm1 flights—
- 5pm–8pm615 flights73.8%
- 8pm–5am—
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 66.6% on time against 96.7% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5pm–8pm window is the busiest, with 615 flights scheduled in it.
Across the year
Delta on SFO to SLC through the year
June is the worst month at 61.7% on time, 27 points below March, the best at 88.4%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. March was the busiest month here, with 149 flights.
Across the week, Saturday is the strongest day at 83.2% on time and Monday the weakest at 72.3%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 59% of the 29,000 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.
- 59%Late-arriving aircraft
- 36%Carrier
- 5%National Airspace System
- 0%Extreme weather
59% 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 29,000 reported delay minutes here, that single category outweighs weather by 59 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 28,550 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 10,000 of the 29,000 delay minutes reported here.
Cancellations are rare at 0.88%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
7.7% 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.
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 67.4% on time across 1,706 flights, 11 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 11 points of difference.
The sample behind these figures is 1,708 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking Delta on SFO to SLC
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 88.4% on time and June 61.7%, a swing of 27 points. If the dates move at all, move them out of June before you think about anything else. 1,693 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to SLC, every carrier
- Delta on SLC to SFO, the return leg
- SkyWest Airlines on SFO to SLC77.2%
- United Airlines on SFO to SLC76.7%
- Frontier Airlines on SFO to SLC69.9%
- Delta Air Lines 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
- The best time of day to fly, according to 7.04 million flight records
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.