Carrier route record
WNSLC→LAX
Southwest Airlines · Salt Lake City to Los Angeles
- Flights
- 374
- Period
- July 2025 to June 2026
- Share of route
- 9%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SLC to LAX lands a B+, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 45 minutes on average. That is a workable record, not a spotless one. That rests on 374 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 691 at 89.6% on time.
SkyWest Airlines is the most reliable of the three carriers covered here at 89.6% on time across 691 flights.
Key figures
On time
80.4%
Arrivals under 15 minutes late, of 373 completed flights
Avg delay
46 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.81%
Whole route
86.2%
Every carrier on SLC to LAX, 4,146 flights
These figures cover 374 flights between July 2025 and June 2026. The median arrival is 5 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
Southwest against every carrier on SLC to LAX
Southwest flew 374 of the 4,146 flights on SLC to LAX, about 9% of it. Its 80.4% on time is 6 points worse than the route as a whole, which runs 86.2%. Ranked by on-time rate it is last of six carriers on the route, where the range runs from United at 91.9% to Southwest at 80.4%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The three carriers here are closely matched: 4 points 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 |
|---|---|---|---|---|---|
| United Airlinesthin sample | 148 | 91.9% | 34 min | 0.00% | A+ |
| Spirit Airlinesthin sample | 23 | 90.9% | 29 min | 4.35% | A− |
| SkyWest Airlines | 691 | 89.6% | 78 min | 0.00% | A+ |
| Frontier Airlines | 456 | 88.4% | 74 min | 1.54% | A |
| Delta Air Lines | 2,454 | 85.4% | 51 min | 0.41% | A+ |
| Southwest Airlines (this page) | 374 | 80.4% | 46 min | 0.27% | B+ |
No carrier stands out. SkyWest tops the table at 89.6%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 13 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am6 flights—
- 8am–11am20 flights—
- 11am–2pm151 flights82.1%
- 2pm–5pm86 flights84.7%
- 5pm–8pm111 flights72.1%
- 8pm–5am—
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 2pm–5pm slot at 84.7% on time, ahead of 5pm–8pm at 72.1%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 11am–2pm window is the busiest, with 151 flights scheduled in it.
Across the year
Southwest on SLC to LAX through the year
July is the worst month at 64.5% on time, 36 points below November, the best at 100.0%. 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. August was the busiest month here, with 34 flights.
Across the week, Saturday is the strongest day at 89.1% on time and Thursday the weakest at 61.5%. 28 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 58% of the 3,334 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.
- 58%Late-arriving aircraft
- 34%Carrier
- 8%National Airspace System
58% 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 3,334 reported delay minutes here, that single category outweighs weather by 58 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 3,334 reported delay minutes.
Cancellations are rare at 0.27%, 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
Badly late arrivals are rare here: only 4.0% 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 590 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 81.7% on time across 374 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.
One caution: this is a thin sample. 374 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 Southwest on SLC to LAX
Put together: treat all of this as provisional. 374 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 80.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 373 completed flights over 12 months sit behind that.
Related
Where to go next
- SLC to LAX, every carrier
- Southwest on LAX to SLC, the return leg
- United Airlines on SLC to LAX91.9%
- SkyWest Airlines on SLC to LAX89.6%
- Frontier Airlines on SLC to LAX88.4%
- Delta Air Lines on SLC to LAX85.4%
- Southwest Airlines network-wide record
- Salt Lake City International (SLC) delay statistics
- Los Angeles International (LAX) 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.