Carrier route record
WNSLC→LAX
Southwest Airlines · Salt Lake City to Los Angeles
- 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 SLC to LAX lands a B+, 3 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, SkyWest Airlines, flew 720 at 91.1% on time.
SkyWest Airlines is the most reliable of the three carriers covered here at 91.1% on time across 720 flights.
Key figures
On time
80.3%
Arrivals under 15 minutes late, of 370 completed flights
Avg delay
44 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.89%
Whole route
85.6%
Every carrier on SLC to LAX, 4,196 flights
These figures cover 371 flights between September 2025 and August 2026. The median arrival is 4 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 SLC to LAX
Southwest flew 371 of the 4,196 flights on SLC to LAX, about 9% of it. Its 80.3% on time is 5 points worse than the route as a whole, which runs 85.6%. 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 80.3%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 91.1% of the time; Delta Air Lines manages 83.5%. Sample sizes sit next to every figure, because a two-point gap across 2,459 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlinesthin sample | 148 | 91.9% | 34 min | 0.00% | A+ |
| SkyWest Airlines | 720 | 91.1% | 77 min | 0.00% | A+ |
| Spirit Airlinesthin sample | 23 | 90.9% | 29 min | 4.35% | A− |
| Frontier Airlines | 475 | 90.0% | 73 min | 1.05% | A |
| Delta Air Lines | 2,459 | 83.5% | 52 min | 0.53% | B+ |
| Southwest Airlines (this page) | 371 | 80.3% | 44 min | 0.27% | B+ |
SkyWest leads Delta by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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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 15 points, against 8 points between the best and worst carrier.
- 5am–8am5 flights—
- 8am–11am16 flights—
- 11am–2pm163 flights84.0%
- 2pm–5pm84 flights83.1%
- 5pm–8pm103 flights68.9%
- 8pm–5am—
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 84.0% on time, ahead of 5pm–8pm at 68.9%. 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 163 flights scheduled in it.
Across the year
Southwest on SLC to LAX through the year
August 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. September was the busiest month here, with 34 flights.
Across the week, Wednesday is the strongest day at 86.3% on time and Thursday the weakest at 67.3%, a spread of 19 points.
Arrival by arrival
How late Southwest on SLC to LAX runs when it is late
The 73 late arrivals split 29 under half an hour, 30 between 30 and 60 minutes, and 14 an hour or more.
- 15+ min early92 flights24.9%
- Within 15 min205 flights55.4%
- 15–29 min late29 flights7.8%
- 30–59 min late30 flights8.1%
- 1–2 hours late10 flights2.7%
- 2+ hours late4 flights1.1%
Scale runs 0% to 100%.
Share of 370 completed flights by arrival against schedule.
A late pushback is often recovered here: of 110 departures that left 15 minutes late or more, 42 still arrived on time. Only 5 left on time and still arrived late.
The worst days
Worst days for Southwest on SLC to LAX
The latest arrival of the period was on 14 December 2025, 3 hours 1 minute behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 14 December 2025 | 3 hours 1 minute | Late-arriving aircraft |
| 29 September 2025 | 2 hours 26 minutes | Late-arriving aircraft |
| 16 March 2026 | 2 hours 18 minutes | Carrier |
| 25 December 2025 | 2 hours | Late-arriving aircraft |
| 13 August 2026 | 1 hour 50 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 63% of the 3,190 delay minutes carriers reported here, and the remaining four split what is left.
- 63%Late-arriving aircraft
- 27%Carrier
- 10%National Airspace System
63% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,190 reported delay minutes here, that single category outweighs weather by 63 to one. The split is drawn from 3,190 reported delay minutes.
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 3.8% 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 79.7% 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 SLC to LAX
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 80.3% 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
- 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 LAX91.1%
- Frontier Airlines on SLC to LAX90.0%
- Delta Air Lines on SLC to LAX83.5%
- 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 7.05 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.