Route reliability record
SLC→SAN
Salt Lake City to San Diego
- Flights
- 2,958
- Period
- July 2025 to June 2026
- Distance
- 626 mi
- Carriers
- 5
This route lands a B+, 6 points better than the national rate of 77.6%. About one flight in six arrive 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That is a workable record, not a spotless one. That rests on 2,958 flights, of which SkyWest Airlines flew 685 at 85.9% on time.
SkyWest Airlines is the most reliable of the three carriers covered here at 85.9% on time across 685 flights.
Key figures
On time
83.2%
Arrivals under 15 minutes late, of 2,923 completed flights
Avg delay
54 min
Across delayed arrivals only, not all flights
Cancelled
0.85%
National rate is 1.81%
Best carrier
SkyWest
85.9% on time across 685 flights
These figures cover 2,958 flights between July 2025 and June 2026. The median arrival is 6 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
Which airline is most reliable on SLC to SAN
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 85.9% of the time; Southwest Airlines manages 75.8%. Sample sizes sit next to every figure, because a two-point gap across 408 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlines | 685 | 85.9% | 58 min | 1.02% | A |
| Frontier Airlinesthin sample | 133 | 84.6% | 50 min | 2.26% | B |
| Delta Air Lines | 1,731 | 83.8% | 55 min | 0.81% | B+ |
| Southwest Airlines | 408 | 75.8% | 47 min | 0.25% | B+ |
SkyWest leads Southwest by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 17 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am556 flights93.5%
- 8am–11am340 flights83.0%
- 11am–2pm628 flights82.6%
- 2pm–5pm552 flights76.8%
- 5pm–8pm504 flights79.6%
- 8pm–5am378 flights83.6%
Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.5% of the time, against 76.8% for the afternoon window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 628 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 15 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.
June is the worst month at 76.5% on time, 15 points below March, the best at 91.0%. 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 293 flights.
Across the week, Tuesday is the strongest day at 87.6% on time and Thursday the weakest at 79.2%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 26,000 reported delay minutes.
- 40%Carrier
- 30%Late-arriving aircraft
- 25%National Airspace System
- 5%Extreme weather
The largest share of delay minutes, 40%, 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 26,000 delay minutes reported here. The split is drawn from 26,309 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 93.5% on time here.
Cancellations are rare at 0.85%, 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 actually costs
Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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. 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 runs 84.4% on time across 2,961 flights, within about a point 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 2,958 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 91.0% on time and June 76.5%, a swing of 15 points. If the dates move at all, move them out of June before you think about anything else. 2,923 completed flights over 12 months sit behind that.
Common questions
SLC to SAN questions
How often is SLC to SAN delayed?
About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.8% of the 2,958 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 55 minutes on average.
Which airline is most reliable on SLC to SAN?
SkyWest Airlines leads at 85.9% on time across 685 flights. Southwest Airlines is at the other end on 75.8%, a gap of 10 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 SLC to SAN?
The 5am–8am departure window is the strongest at 93.5% on time. The 2pm–5pm window is the weakest at 76.8%, 17 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 June delays on SLC to SAN?
June is the weakest month at 76.5% on time, compared with 91.0% in March. Across the year that is 15 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
- SAN to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- San Diego International (SAN) delay statistics
- Alaska Airlines on-time record100.0%
- SkyWest Airlines on-time record85.9%
- Frontier Airlines on-time record84.6%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SLC to SAN and SAN to SLC are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.