Route reliability record
SAN→SLC
San Diego to Salt Lake City
- Flights
- 3,100
- Period
- September 2025 to August 2026
- Distance
- 626 mi
- Carriers
- 4
This route lands a B+, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 3,100 SAN to SLC flights, of which Delta Air Lines flew 1,739 at 88.1% on time.
Best time to fly SAN to SLC: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 96.0% of the time and Wednesday flights 88.6%, against 83.0% for the route overall.
Delta Air Lines is the most reliable of the three carriers covered here at 88.1% on time across 1,739 flights.
Key figures
On time
83.0%
Arrivals under 15 minutes late, of 3,072 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.74%
National rate is 1.89%
Best carrier
Delta
88.1% on time across 1,739 flights
These figures cover 3,100 flights between September 2025 and August 2026. The median arrival is 9 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.
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Carrier by carrier
Which airline is most reliable on SAN to SLC
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 88.1% of the time; Southwest Airlines manages 72.8%. Sample sizes sit next to every figure, because a two-point gap across 436 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 1,739 | 88.1% | 71 min | 0.92% | A+ |
| Frontier Airlinesthin sample | 107 | 84.9% | 101 min | 0.93% | B+ |
| SkyWest Airlines | 818 | 77.6% | 62 min | 0.61% | B+ |
| Southwest Airlines | 436 | 72.8% | 45 min | 0.23% | C+ |
The spread between Delta and Southwest is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
Flight by flight
Flights on SAN to SLC
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly San Diego to Salt Lake City
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SAN → SLCSan Diego to Salt Lake City | Delta Air Lines | 87.3% | 88.1% | 0.92% | 5am–8am, Tue | DL 1117 06:15 |
| 2. SAN → SLCSan Diego to Salt Lake City | SkyWest Airlines | 77.1% | 77.6% | 0.61% | 8am–11am, Wed | OO 3017 18:49 |
| 3. SAN → SLCSan Diego to Salt Lake City | Southwest Airlines | 72.6% | 72.8% | 0.23% | 8am–11am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 32 points, against 15 points between the best and worst carrier.
- 5am–8am404 flights96.0%
- 8am–11am719 flights91.3%
- 11am–2pm526 flights83.3%
- 2pm–5pm275 flights64.0%
- 5pm–8pm1,047 flights78.2%
- 8pm–5am129 flights75.8%
Scale runs 55% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 96.0% of the time, against 64.0% for the afternoon window. That is 32 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 1,047 flights scheduled in it.
Explore
Filter SAN to SLC by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SAN to SLC, the best departure window is 5am–8am at 96.0% on time and the worst is 2pm–5pm at 64.0%, a wide gap of 32.0 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am96.0%
- 8–11am91.3%
- 11am–2pm83.3%
- 2–5pm64.0%
- 5–8pm78.2%
- 8pm–5am75.8%
best all US flightsScale 55% to 100%.
Across the year
When delays peak on this route
This route's year swings by 19 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 69.2% on time, 19 points below April, the best at 88.5%. 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. August was the busiest month here, with 297 flights.
Across the week, Wednesday is the strongest day at 88.6% on time and Friday the weakest at 76.2%, a spread of 12 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 57% of the 33,000 delay minutes carriers reported here, and the remaining four split what is left.
- 57%Late-arriving aircraft
- 28%Carrier
- 12%National Airspace System
- 3%Extreme weather
- 0%Security
57% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 33,000 reported delay minutes here, that single category outweighs weather by 18 to one. The split is drawn from 32,894 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 96.0% on time here.
Cancellations are rare at 0.74%, below the national 1.89% 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 actually costs
5.7% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
The 626 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.
The return leg runs 80.9% on time across 3,097 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 3,100 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.
Work out the risk of missing a connection in SLC after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 88.5% on time and August 69.2%, a swing of 19 points. If the dates move at all, move them out of August before you think about anything else. 3,072 completed flights over 12 months sit behind that.
Common questions
SAN to SLC questions
How often is SAN to SLC delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.0% of the 3,100 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SAN to SLC?
Delta Air Lines leads at 88.1% on time across 1,739 flights. Southwest Airlines is at the other end on 72.8%, a gap of 15 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SAN to SLC?
The 5am–8am departure window is the strongest at 96.0% on time. The 2pm–5pm window is the weakest at 64.0%, 32 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on SAN to SLC?
August is the weakest month at 69.2% on time, compared with 88.5% in April. Across the year that is 19 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SLC to SAN — the return legseparate record
- San Diego International (SAN) delay statistics
- Salt Lake City International (SLC) delay statistics
- Delta Air Lines on SAN to SLC88.1%
- Frontier Airlines on SAN to SLC84.9%
- SkyWest Airlines on SAN to SLC77.6%
- Southwest Airlines on SAN to SLC72.8%
- SAN to SFO, a related route59.5%
- DEN to SLC, a related route78.2%
- SAN to DEN, a related route78.4%
- Delta Air Lines on-time record88.1%
- Frontier Airlines on-time record84.9%
- SkyWest Airlines on-time record77.6%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. SAN to SLC and SLC to SAN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.