Carrier route record
WNDEN→PHX
Southwest Airlines · Denver to Phoenix
- Flights
- 3,950
- Period
- July 2025 to June 2026
- Share of route
- 44%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on DEN to PHX sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 3,950 flights. The strongest carrier on the route with a full sample, United Airlines, flew 2,369 at 80.5% on time.
United Airlines is the most reliable of the three carriers covered here at 80.5% on time across 2,369 flights.
Key figures
On time
72.1%
Arrivals under 15 minutes late, of 3,899 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
1.14%
National rate is 1.81%
Whole route
75.7%
Every carrier on DEN to PHX, 8,930 flights
These figures cover 3,950 flights between July 2025 and June 2026. Beyond the headline rate, 8.3% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Southwest against every carrier on DEN to PHX
Southwest flew 3,950 of the 8,930 flights on DEN to PHX, about 44% of it. Its 72.1% on time is 4 points worse than the route as a whole, which runs 75.7%. Ranked by on-time rate it is last of six carriers on the route, where the range runs from United at 80.5% to Southwest at 72.1%. 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 Airlines | 2,369 | 80.5% | 63 min | 0.34% | B+ |
| SkyWest Airlinesthin sample | 18 | 77.8% | 23 min | 0.00% | B+ |
| Frontier Airlines | 1,432 | 77.4% | 69 min | 0.63% | B+ |
| American Airlines | 972 | 76.9% | 120 min | 0.82% | B+ |
| Envoy Airthin sample | 189 | 72.9% | 101 min | 0.53% | C+ |
| Southwest Airlines (this page) | 3,950 | 72.1% | 56 min | 1.14% | C |
No carrier stands out. United tops the table at 80.5%, 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 41 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am645 flights93.1%
- 8am–11am792 flights86.6%
- 11am–2pm642 flights74.1%
- 2pm–5pm687 flights65.6%
- 5pm–8pm660 flights52.1%
- 8pm–5am524 flights55.5%
Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 52.1% on time, against 93.1% 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 8am–11am window is the busiest, with 792 flights scheduled in it.
Across the year
Southwest on DEN to PHX through the year
July is the worst month at 58.8% on time, 22 points below January, the best at 80.8%. 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 383 flights.
Across the week, Tuesday is the strongest day at 78.2% on time and Sunday the weakest at 66.8%. 11 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 52% of the 61,000 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.
- 52%Late-arriving aircraft
- 33%Carrier
- 13%National Airspace System
- 1%Extreme weather
- 0%Security
52% 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 61,000 reported delay minutes here, that single category outweighs weather by 40 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 60,559 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 93.1% on time here.
Cancellations sit at 1.14% against a national 1.81%, which is ordinary. Diversions add another 0.15%.
Connections and stage length
What a delay here costs
8.3% 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 about an hour, which a normal layover absorbs.
The 602 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 72.8% on time across 3,942 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.
The sample behind these figures is 3,950 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 DEN to PHX
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 80.8% on time and July 58.8%, a swing of 22 points. If the dates move at all, move them out of July before you think about anything else. 3,899 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to PHX, every carrier
- Southwest on PHX to DEN, the return leg
- United Airlines on DEN to PHX80.5%
- Frontier Airlines on DEN to PHX77.4%
- American Airlines on DEN to PHX76.9%
- Envoy Air on DEN to PHX72.9%
- Southwest Airlines network-wide record
- Denver International (DEN) delay statistics
- Phoenix Sky Harbor International (PHX) 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.