Carrier route record
WNPHX→SLC
Southwest Airlines · Phoenix to Salt Lake City
- Flights
- 1,858
- Period
- July 2025 to June 2026
- Share of route
- 32%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on PHX to SLC sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land roughly 50 minutes behind schedule. That rests on 1,858 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 1,708 at 90.4% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 90.4% on time across 1,708 flights.
Key figures
On time
75.5%
Arrivals under 15 minutes late, of 1,852 completed flights
Avg delay
48 min
Across delayed arrivals only, not all flights
Cancelled
0.32%
National rate is 1.81%
Whole route
83.0%
Every carrier on PHX to SLC, 5,757 flights
These figures cover 1,858 flights between July 2025 and June 2026. The median arrival is 2 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 PHX to SLC
Southwest flew 1,858 of the 5,757 flights on PHX to SLC, about 32% of it. Its 75.5% on time is 8 points worse than the route as a whole, which runs 83.0%. Ranked by on-time rate it is last of six carriers on the route, where the range runs from Delta at 90.4% to Southwest at 75.5%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 90.4% of the time; SkyWest Airlines manages 83.1%. Sample sizes sit next to every figure, because a two-point gap across 1,159 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 1,708 | 90.4% | 75 min | 0.59% | A+ |
| American Airlinesthin sample | 266 | 86.7% | 70 min | 0.38% | A+ |
| Frontier Airlines | 677 | 83.6% | 78 min | 1.77% | B |
| Envoy Airthin sample | 89 | 83.1% | 46 min | 0.00% | B+ |
| SkyWest Airlines | 1,159 | 83.1% | 67 min | 0.26% | B+ |
| Southwest Airlines (this page) | 1,858 | 75.5% | 48 min | 0.32% | B+ |
Delta leads SkyWest by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 39 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am170 flights98.2%
- 8am–11am382 flights86.9%
- 11am–2pm281 flights81.1%
- 2pm–5pm291 flights78.4%
- 5pm–8pm335 flights63.0%
- 8pm–5am399 flights59.4%
Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 59.4% on time, against 98.2% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8pm–5am window is the busiest, with 399 flights scheduled in it.
Across the year
Southwest on PHX to SLC through the year
June is the worst month at 59.4% on time, 24 points below September, the best at 83.6%. 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 175 flights.
Across the week, Tuesday is the strongest day at 83.2% on time and Thursday the weakest at 67.3%. 16 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 61% of the 22,000 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.
- 61%Late-arriving aircraft
- 34%Carrier
- 5%National Airspace System
- 0%Extreme weather
- 0%Security
61% 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 22,000 reported delay minutes here, that single category outweighs weather by 61 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 21,975 reported delay minutes.
The largest share of delay minutes, 34%, 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 7,487 of the 22,000 delay minutes reported here.
Cancellations are rare at 0.32%, 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
5.7% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 50 minutes, which a normal layover absorbs.
The 507 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 is a different operation and performs like one: it runs 79.6% on time across 1,860 flights, 4 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
The sample behind these figures is 1,858 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 Southwest on PHX to SLC
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 83.6% on time and June 59.4%, a swing of 24 points. If the dates move at all, move them out of June before you think about anything else. 1,852 completed flights over 12 months sit behind that.
Related
Where to go next
- PHX to SLC, every carrier
- Southwest on SLC to PHX, the return leg
- Delta Air Lines on PHX to SLC90.4%
- American Airlines on PHX to SLC86.7%
- Frontier Airlines on PHX to SLC83.6%
- SkyWest Airlines on PHX to SLC83.1%
- Southwest Airlines network-wide record
- Phoenix Sky Harbor International (PHX) 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.