Carrier route record
WNDTW→DEN
Southwest Airlines · Detroit to Denver
- Flights
- 649
- Period
- July 2025 to June 2026
- Share of route
- 21%
- Carriers
- 5
Historical statistics for July 2025 to June 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 77.6%. The late ones land about 50 minutes behind schedule. That rests on 649 flights. The strongest carrier on the route with a full sample, United Airlines, flew 727 at 83.7% on time.
United Airlines is the most reliable of the three carriers covered here at 83.7% on time across 727 flights.
Key figures
On time
74.7%
Arrivals under 15 minutes late, of 644 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
0.62%
National rate is 1.81%
Whole route
79.7%
Every carrier on DTW to DEN, 3,089 flights
These figures cover 649 flights between July 2025 and June 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.
Carrier by carrier
Southwest against every carrier on DTW to DEN
Southwest flew 649 of the 3,089 flights on DTW to DEN, about 21% of it. Its 74.7% on time is 5 points worse than the route as a whole, which runs 79.7%. 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 74.7%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The three carriers here are closely matched: 5 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 | 727 | 83.7% | 72 min | 0.69% | B+ |
| Frontier Airlines | 459 | 83.2% | 73 min | 0.44% | B+ |
| Delta Air Lines | 1,253 | 78.6% | 58 min | 0.32% | B+ |
| Southwest Airlines (this page) | 649 | 74.7% | 51 min | 0.62% | C+ |
No carrier stands out. United tops the table at 83.7%, 5 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 54 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am260 flights89.2%
- 8am–11am62 flights98.4%
- 11am–2pm71 flights87.3%
- 2pm–5pm111 flights58.7%
- 5pm–8pm140 flights44.2%
- 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: 44.2% on time, against 98.4% 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 260 flights scheduled in it.
Across the year
Southwest on DTW to DEN through the year
July is the worst month at 58.1% on time, 32 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, Tuesday is the strongest day at 80.4% on time and Sunday the weakest at 67.0%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 8,284 reported delay minutes.
- 40%Late-arriving aircraft
- 32%National Airspace System
- 27%Carrier
- 1%Extreme weather
40% 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 8,284 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 8,284 reported delay minutes.
32% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,673 minutes out of 8,284, against a national NAS share of 21%.
Cancellations are rare at 0.62%, 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
5.6% 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 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. 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 56.7% on time across 649 flights, 18 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 18 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 74.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 644 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 DEN83.7%
- Frontier Airlines on DTW to DEN83.2%
- Delta Air Lines on DTW to DEN78.6%
- 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 7.04 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.