Carrier route record
WNLAX→SLC
Southwest Airlines · Los Angeles to Salt Lake City
- 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 LAX to SLC lands a B+, 4 points better than the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 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
81.7%
Arrivals under 15 minutes late, of 372 completed flights
Avg delay
46 min
Across delayed arrivals only, not all flights
Cancelled
0.53%
National rate is 1.81%
Whole route
87.7%
Every carrier on LAX to SLC, 4,144 flights
These figures cover 374 flights between July 2025 and June 2026. The median arrival is 7 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 LAX to SLC
Southwest flew 374 of the 4,144 flights on LAX to SLC, about 9% of it. Its 81.7% on time is 6 points worse than the route as a whole, which runs 87.7%. Ranked by on-time rate it is last of six carriers on the route, where the range runs from Spirit at 90.9% to Southwest at 81.7%. 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 |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 23 | 90.9% | 29 min | 4.35% | A− |
| SkyWest Airlines | 691 | 89.6% | 87 min | 0.00% | A+ |
| United Airlinesthin sample | 149 | 88.6% | 65 min | 0.00% | A+ |
| Delta Air Lines | 2,451 | 88.5% | 79 min | 0.41% | A+ |
| Frontier Airlines | 456 | 85.2% | 76 min | 0.88% | A+ |
| Southwest Airlines (this page) | 374 | 81.7% | 46 min | 0.53% | 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 29 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am84 flights97.6%
- 8am–11am127 flights76.4%
- 11am–2pm96 flights88.4%
- 2pm–5pm60 flights68.3%
- 5pm–8pm7 flights—
- 8pm–5am—
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 97.6% of the time, against 68.3% 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 8am–11am window is the busiest, with 127 flights scheduled in it.
Across the year
Southwest on LAX to SLC through the year
June is the worst month at 50.0% on time, 50 points below September, 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, Tuesday is the strongest day at 92.5% on time and Thursday the weakest at 74.5%. 18 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 59% of the 3,144 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
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 3,144 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 3,144 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 1,134 of the 3,144 delay minutes reported here.
Cancellations are rare at 0.53%, 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 80.4% 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 LAX to SLC
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 81.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 372 completed flights over 12 months sit behind that.
Related
Where to go next
- LAX to SLC, every carrier
- Southwest on SLC to LAX, the return leg
- SkyWest Airlines on LAX to SLC89.6%
- United Airlines on LAX to SLC88.6%
- Delta Air Lines on LAX to SLC88.5%
- Frontier Airlines on LAX to SLC85.2%
- Southwest Airlines network-wide record
- Los Angeles International (LAX) 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.