Carrier route record
WNDEN→DTW
Southwest Airlines · Denver to Detroit
- 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 DEN to DTW earns a D, which is as low as this site's scale goes for a reason. Only 56.7% of flights arrive inside the 15-minute window, 21 points worse than the national rate of 77.6%. Late arrivals average roughly 50 minutes. Treat any tight connection here as a coin flip. That rests on 649 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 1,252 at 86.2% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 86.2% on time across 1,252 flights.
Key figures
On time
56.7%
Arrivals under 15 minutes late, of 642 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
1.08%
National rate is 1.81%
Whole route
77.6%
Every carrier on DEN to DTW, 3,088 flights
These figures cover 649 flights between July 2025 and June 2026. Beyond the headline rate, 10.9% 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 DTW
Southwest flew 649 of the 3,088 flights on DEN to DTW, about 21% of it. Its 56.7% on time is 21 points worse than the route as a whole, which runs 77.6%. 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 56.7%. One 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 86.2% of the time; United Airlines manages 79.7%. Sample sizes sit next to every figure, because a two-point gap across 727 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| Delta Air Lines | 1,252 | 86.2% | 75 min | 0.48% | A+ |
| Frontier Airlines | 459 | 80.3% | 76 min | 0.22% | B+ |
| United Airlines | 727 | 79.7% | 60 min | 0.00% | B+ |
| Southwest Airlines (this page) | 649 | 56.7% | 49 min | 1.08% | D |
Delta leads United 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 23 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am112 flights66.1%
- 11am–2pm195 flights68.6%
- 2pm–5pm30 flights53.3%
- 5pm–8pm278 flights45.4%
- 8pm–5am34 flights51.5%
Scale runs 35% to 75%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 45.4% on time, against 68.6% for the 11am–2pm 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 5pm–8pm window is the busiest, with 278 flights scheduled in it.
Across the year
Southwest on DEN to DTW through the year
November is the best month on the calendar at 77.3% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. July was the busiest month here, with 62 flights.
Across the week, Saturday is the strongest day at 64.9% on time and Monday the weakest at 45.8%. 19 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 60% of the 13,000 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.
- 60%Late-arriving aircraft
- 27%Carrier
- 12%National Airspace System
- 1%Extreme weather
- 0%Security
60% 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 13,000 reported delay minutes here, that single category outweighs weather by 60 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 13,477 reported delay minutes.
Cancellations sit at 1.08% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.9% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
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 74.7% on time across 649 flights, 18 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 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 DEN to DTW
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 56.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 642 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to DTW, every carrier
- Southwest on DTW to DEN, the return leg
- Delta Air Lines on DEN to DTW86.2%
- Frontier Airlines on DEN to DTW80.3%
- United Airlines on DEN to DTW79.7%
- Southwest Airlines network-wide record
- Denver International (DEN) delay statistics
- Detroit Metropolitan Wayne County (DTW) 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.