Carrier route record
WNDEN→TUS
Southwest Airlines · Denver to Tucson
- Flights
- 1,202
- Period
- July 2025 to June 2026
- Share of route
- 44%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on DEN to TUS sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land about 50 minutes behind schedule. That rests on 1,202 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 622 at 84.3% on time.
The national on-time rate over the same period is 77.6%, so Southwest on DEN to TUS runs 7 points behind the country as a whole. Across a thousand flights that is about 70 extra late arrivals.
Key figures
On time
70.6%
Arrivals under 15 minutes late, of 1,194 completed flights
Avg delay
50 min
Across delayed arrivals only, not all flights
Cancelled
0.42%
National rate is 1.81%
Whole route
77.1%
Every carrier on DEN to TUS, 2,755 flights
These figures cover 1,202 flights between July 2025 and June 2026. Beyond the headline rate, 8.1% 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 TUS
Southwest flew 1,202 of the 2,755 flights on DEN to TUS, about 44% of it. Its 70.6% on time is 7 points worse than the route as a whole, which runs 77.1%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from SkyWest at 84.3% to Southwest at 70.6%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two 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 |
|---|---|---|---|---|---|
| SkyWest Airlines | 622 | 84.3% | 76 min | 0.48% | B+ |
| Frontier Airlinesthin sample | 95 | 81.9% | 50 min | 1.05% | B |
| United Airlines | 836 | 80.6% | 57 min | 0.12% | B+ |
| Southwest Airlines (this page) | 1,202 | 70.6% | 50 min | 0.42% | C+ |
No carrier stands out. SkyWest tops the table at 84.3%, 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 31 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am19 flights—
- 8am–11am327 flights88.6%
- 11am–2pm163 flights78.5%
- 2pm–5pm194 flights58.6%
- 5pm–8pm160 flights57.5%
- 8pm–5am339 flights62.3%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 57.5% on time, against 88.6% for the 8am–11am 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 339 flights scheduled in it.
Across the year
Southwest on DEN to TUS through the year
July is the worst month at 57.8% on time, 28 points below November, the best at 85.4%. 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. October was the busiest month here, with 117 flights.
Across the week, Tuesday is the strongest day at 78.8% on time and Thursday the weakest at 64.1%. 15 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 57% of the 18,000 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.
- 57%Late-arriving aircraft
- 32%Carrier
- 9%National Airspace System
- 1%Extreme weather
- 0%Security
57% 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 18,000 reported delay minutes here, that single category outweighs weather by 49 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 17,648 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 88.6% on time here.
Cancellations are rare at 0.42%, 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
8.1% 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 50 minutes, which a normal layover absorbs.
The 639 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 80.1% on time across 1,202 flights, 10 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 10 points of difference.
The sample behind these figures is 1,202 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 TUS
Put together: the calendar is the biggest lever here, not the carrier or the hour. November runs 85.4% on time and July 57.8%, a swing of 28 points. If the dates move at all, move them out of July before you think about anything else. 1,194 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to TUS, every carrier
- Southwest on TUS to DEN, the return leg
- SkyWest Airlines on DEN to TUS84.3%
- United Airlines on DEN to TUS80.6%
- Southwest Airlines network-wide record
- Denver International (DEN) 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.