Carrier route record
WNLAX→SLC
Southwest Airlines · Los Angeles to Salt Lake City
- Flights
- 371
- Period
- September 2025 to August 2026
- Share of route
- 9%
- Carriers
- 6
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on LAX to SLC lands a B+, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That rests on 371 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 2,457 at 88.4% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 88.4% on time across 2,457 flights.
Key figures
On time
79.7%
Arrivals under 15 minutes late, of 370 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.89%
Whole route
87.2%
Every carrier on LAX to SLC, 4,195 flights
These figures cover 371 flights between September 2025 and August 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.
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Carrier by carrier
Southwest against every carrier on LAX to SLC
Southwest flew 371 of the 4,195 flights on LAX to SLC, about 9% of it. Its 79.7% on time is 8 points worse than the route as a whole, which runs 87.2%. 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 79.7%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The three carriers here are closely matched: 3 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− |
| United Airlinesthin sample | 149 | 88.6% | 65 min | 0.00% | A+ |
| Delta Air Lines | 2,457 | 88.4% | 80 min | 0.53% | A+ |
| SkyWest Airlines | 720 | 88.0% | 69 min | 0.00% | A+ |
| Frontier Airlines | 475 | 85.3% | 75 min | 1.26% | A |
| Southwest Airlines (this page) | 371 | 79.7% | 47 min | 0.27% | B+ |
No carrier stands out. Delta tops the table at 88.4%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 3 points between the best and worst carrier.
- 5am–8am62 flights96.8%
- 8am–11am128 flights78.1%
- 11am–2pm109 flights83.3%
- 2pm–5pm65 flights67.7%
- 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 96.8% of the time, against 67.7% 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 128 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. September was the busiest month here, with 34 flights.
Across the week, Tuesday is the strongest day at 86.5% on time and Wednesday the weakest at 72.5%, a spread of 14 points.
Arrival by arrival
How late Southwest on LAX to SLC runs when it is late
The 75 late arrivals split 34 under half an hour, 24 between 30 and 60 minutes, and 17 an hour or more.
- 15+ min early80 flights21.6%
- Within 15 min215 flights58.1%
- 15–29 min late34 flights9.2%
- 30–59 min late24 flights6.5%
- 1–2 hours late12 flights3.2%
- 2+ hours late5 flights1.4%
Scale runs 0% to 100%.
Share of 370 completed flights by arrival against schedule.
18 of 86 late departures made up the time and arrived on time, 21% of them. Only 7 left on time and still arrived late.
The worst days
Worst days for Southwest on LAX to SLC
The latest arrival of the period was on 7 August 2026, 5 hours 3 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 August 2026 | 5 hours 3 minutes | Carrier |
| 5 November 2025 | 2 hours 17 minutes | Late-arriving aircraft |
| 24 December 2025 | 2 hours 12 minutes | Late-arriving aircraft |
| 1 January 2026 | 2 hours 7 minutes | Late-arriving aircraft |
| 11 December 2025 | 2 hours | Carrier |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 53% of the 3,491 delay minutes carriers reported here, and the remaining four split what is left.
- 53%Late-arriving aircraft
- 41%Carrier
- 6%National Airspace System
53% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,491 reported delay minutes here, that single category outweighs weather by 53 to one. The split is drawn from 3,491 reported delay minutes.
The largest share of delay minutes, 41%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,429 of the 3,491 delay minutes reported here.
Cancellations are rare at 0.27%, 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 costs
Badly late arrivals are rare here: only 4.6% land an hour or more behind schedule, against 8.3% 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.
The return leg runs 80.3% on time across 371 flights, within half 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. 371 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. 371 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 79.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 370 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
- United Airlines on LAX to SLC88.6%
- Delta Air Lines on LAX to SLC88.4%
- SkyWest Airlines on LAX to SLC88.0%
- Frontier Airlines on LAX to SLC85.3%
- 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 7.05 million flight records
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.