Carrier route record
WNBHM→DEN
Southwest Airlines · Birmingham to Denver
- Flights
- 509
- Period
- September 2025 to August 2026
- Share of route
- 41%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on BHM to DEN lands a B+, level with the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 509 flights, with a median arrival 3 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate Southwest on BHM to DEN from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.8%
Arrivals under 15 minutes late, of 508 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
Whole route
83.2%
Every carrier on BHM to DEN, 1,236 flights
These figures cover 509 flights between September 2025 and August 2026. The median arrival is 3 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
Southwest against every carrier on BHM to DEN
Southwest flew 509 of the 1,236 flights on BHM to DEN, about 41% of it. Its 77.8% on time is 5 points worse than the route as a whole, which runs 83.2%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from SkyWest at 90.0% to United at 72.1%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 604 | 90.0% | 81 min | 0.33% | A+ |
| Southwest Airlines (this page) | 509 | 77.8% | 57 min | 0.00% | B+ |
| United Airlinesthin sample | 123 | 72.1% | 79 min | 0.81% | C+ |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 45 points, against half a point between the best and worst carrier.
- 5am–8am186 flights93.0%
- 8am–11am139 flights85.6%
- 11am–2pm32 flights84.4%
- 2pm–5pm15 flights—
- 5pm–8pm137 flights48.5%
- 8pm–5am—
Scale runs 40% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 48.5% on time, against 93.0% 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 5am–8am window is the busiest, with 186 flights scheduled in it.
Across the year
Southwest on BHM to DEN through the year
June is the worst month at 55.4% on time, 38 points below October, the best at 93.5%. 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 58 flights.
Across the week, Saturday is the strongest day at 83.9% on time and Monday the weakest at 71.6%, a spread of 12 points.
Arrival by arrival
How late Southwest on BHM to DEN runs when it is late
The 113 late arrivals split 43 under half an hour, 36 between 30 and 60 minutes, and 34 an hour or more.
- 15+ min early91 flights17.9%
- Within 15 min304 flights59.8%
- 15–29 min late43 flights8.5%
- 30–59 min late36 flights7.1%
- 1–2 hours late20 flights3.9%
- 2+ hours late14 flights2.8%
Scale runs 0% to 100%.
Share of 508 completed flights by arrival against schedule.
34 of 131 late departures made up the time and arrived on time, 26% of them. 16 flights left on time and still arrived late.
The worst days
Worst days for Southwest on BHM to DEN
The latest arrival of the period was on 15 March 2026, 6 hours 27 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in March 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 15 March 2026 | 6 hours 27 minutes | Carrier |
| 28 December 2025 | 4 hours 26 minutes | Late-arriving aircraft |
| 6 March 2026 | 3 hours 3 minutes | National Airspace System |
| 9 March 2026 | 2 hours 55 minutes | Carrier |
| 17 May 2026 | 2 hours 51 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 46% of the 6,471 delay minutes carriers reported here, and the remaining four split what is left.
- 46%Late-arriving aircraft
- 30%National Airspace System
- 22%Carrier
- 2%Extreme weather
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 6,471 reported delay minutes here, that single category outweighs weather by 28 to one. The split is drawn from 6,471 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 93.0% on time here.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
6.7% 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 1,083 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 63.3% on time across 509 flights, 15 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 15 points of difference.
One caution: this is a thin sample. 509 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 BHM to DEN
Put together: treat all of this as provisional. 509 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 77.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 508 completed flights over 12 months sit behind that.
Related
Where to go next
- BHM to DEN, every carrier
- Southwest on DEN to BHM, the return leg
- SkyWest Airlines on BHM to DEN90.0%
- United Airlines on BHM to DEN72.1%
- 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 7.05 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.