Carrier route record
WNDTW→DEN
Southwest Airlines · Detroit to Denver
- Flights
- 649
- Period
- September 2025 to August 2026
- Share of route
- 21%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on DTW to DEN sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 649 flights. The strongest carrier on the route with a full sample, United Airlines, flew 726 at 82.8% on time.
United Airlines is the most reliable of the three carriers covered here at 82.8% on time across 726 flights.
Key figures
On time
73.9%
Arrivals under 15 minutes late, of 643 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
0.62%
National rate is 1.89%
Whole route
79.5%
Every carrier on DTW to DEN, 3,110 flights
These figures cover 649 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
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Carrier by carrier
Southwest against every carrier on DTW to DEN
Southwest flew 649 of the 3,110 flights on DTW to DEN, about 21% of it. Its 73.9% on time is 6 points worse than the route as a whole, which runs 79.5%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from SkyWest at 100.0% to Southwest at 73.9%. One 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 |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 726 | 82.8% | 63 min | 0.69% | B+ |
| Frontier Airlines | 486 | 82.5% | 80 min | 1.03% | B |
| Delta Air Lines | 1,248 | 79.2% | 57 min | 0.16% | B+ |
| Southwest Airlines (this page) | 649 | 73.9% | 60 min | 0.62% | C+ |
No carrier stands out. United tops the table at 82.8%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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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 53 points, against 4 points between the best and worst carrier.
- 5am–8am279 flights91.0%
- 8am–11am43 flights97.7%
- 11am–2pm61 flights83.6%
- 2pm–5pm116 flights56.1%
- 5pm–8pm145 flights44.4%
- 8pm–5am5 flights—
Scale runs 35% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 44.4% on time, against 97.7% 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 5am–8am window is the busiest, with 279 flights scheduled in it.
Across the year
Southwest on DTW to DEN through the year
June is the worst month at 61.0% on time, 29 points below September, the best at 90.0%. 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. July was the busiest month here, with 62 flights.
Across the week, Wednesday is the strongest day at 82.4% on time and Sunday the weakest at 67.0%, a spread of 15 points.
Arrival by arrival
How late Southwest on DTW to DEN runs when it is late
The 168 late arrivals split 66 under half an hour, 55 between 30 and 60 minutes, and 47 an hour or more.
- 15+ min early121 flights18.8%
- Within 15 min354 flights55.1%
- 15–29 min late66 flights10.3%
- 30–59 min late55 flights8.6%
- 1–2 hours late25 flights3.9%
- 2+ hours late22 flights3.4%
Scale runs 0% to 100%.
Share of 643 completed flights by arrival against schedule.
53 of 195 late departures made up the time and arrived on time, 27% of them. 26 flights left on time and still arrived late.
The worst days
Worst days for Southwest on DTW to DEN
The latest arrival of the period was on 13 March 2026, 5 hours 36 minutes 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 |
|---|---|---|
| 13 March 2026 | 5 hours 36 minutes | Late-arriving aircraft |
| 27 July 2026 | 5 hours 6 minutes | Late-arriving aircraft |
| 14 August 2026 | 5 hours 5 minutes | National Airspace System |
| 9 August 2026 | 4 hours 58 minutes | Late-arriving aircraft |
| 18 July 2026 | 4 hours 57 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 44% of the 10,000 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 31%National Airspace System
- 25%Carrier
- 1%Extreme weather
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 10,000 reported delay minutes here, that single category outweighs weather by 44 to one. The split is drawn from 10,074 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 97.7% on time here.
Cancellations are rare at 0.62%, 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
7.3% of arrivals land an hour or more late, close to the national 8.3%, so 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 1,123 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 is a different operation and performs like one: it runs 57.2% on time across 649 flights, 17 points below 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 17 points of difference.
One caution: this is a thin sample. 649 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 DTW to DEN
Put together: treat all of this as provisional. 649 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 73.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 643 completed flights over 12 months sit behind that.
Related
Where to go next
- DTW to DEN, every carrier
- Southwest on DEN to DTW, the return leg
- United Airlines on DTW to DEN82.8%
- Frontier Airlines on DTW to DEN82.5%
- Delta Air Lines on DTW to DEN79.2%
- Southwest Airlines network-wide record
- Detroit Metropolitan Wayne County (DTW) delay statistics
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 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.