Route reliability record
DEN→BHM
Denver to Birmingham
- Flights
- 1,236
- Period
- September 2025 to August 2026
- Distance
- 1,083 mi
- Carriers
- 3
This route sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 1,236 DEN to BHM flights, of which SkyWest Airlines flew 604 at 79.2% on time.
Best time to fly DEN to BHM: a 11am–2pm departure, ideally on a Tuesday. Flights in that window arrived on time 81.8% of the time and Tuesday flights 80.1%, against 72.5% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 5 points behind the country as a whole. Across a thousand flights that is about 48 extra late arrivals.
Key figures
On time
72.5%
Arrivals under 15 minutes late, of 1,232 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
0.32%
National rate is 1.89%
Best carrier
SkyWest
79.2% on time across 604 flights
These figures cover 1,236 flights between September 2025 and August 2026. Beyond the headline rate, 9.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on DEN to BHM
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 79.2% of the time; Southwest Airlines manages 63.3%. Sample sizes sit next to every figure, because a two-point gap across 509 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 604 | 79.2% | 78 min | 0.33% | B+ |
| United Airlinesthin sample | 123 | 77.2% | 56 min | 0.00% | B+ |
| Southwest Airlines | 509 | 63.3% | 63 min | 0.39% | D+ |
The spread between SkyWest and Southwest is 16 points, wide enough that it should decide the booking. On a hundred trips that is 16 more arrivals inside the on-time window.
Flight by flight
Flights on DEN to BHM
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Denver to Birmingham
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. DEN → BHMDenver to Birmingham | SkyWest Airlines | 78.9% | 79.2% | 0.33% | 11am–2pm, Tue | OO 5815 17:30 |
| 2. DEN → BHMDenver to Birmingham | Southwest Airlines | 63.1% | 63.3% | 0.39% | 8am–11am, Tue | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 16 points between the best and worst carrier.
- 5am–8am—
- 8am–11am400 flights78.6%
- 11am–2pm143 flights81.8%
- 2pm–5pm56 flights73.2%
- 5pm–8pm542 flights68.3%
- 8pm–5am95 flights55.8%
Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 55.8% on time, against 81.8% 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 542 flights scheduled in it.
Explore
Filter DEN to BHM by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On DEN to BHM, the best departure window is 11am–2pm at 81.8% on time and the worst is 8pm–5am at 55.8%, a wide gap of 26.0 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am—
- 8–11am78.6%
- 11am–2pm81.8%
- 2–5pm73.2%
- 5–8pm68.3%
- 8pm–5am55.8%
best all US flightsScale 45% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 31 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 55.0% on time, 31 points below November, the best at 86.4%. 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. July was the busiest month here, with 119 flights.
Across the week, Tuesday is the strongest day at 80.1% on time and Friday the weakest at 67.6%, a spread of 13 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 45% of the 23,000 delay minutes carriers reported here, and the remaining four split what is left.
- 45%Late-arriving aircraft
- 30%Carrier
- 21%National Airspace System
- 4%Extreme weather
45% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 23,000 reported delay minutes here, that single category outweighs weather by 11 to one. The split is drawn from 22,939 reported delay minutes.
Cancellations are rare at 0.32%, 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 actually costs
9.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
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 83.2% on time across 1,236 flights, 11 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 11 points of difference.
The sample behind these figures is 1,236 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.
Work out the risk of missing a connection in BHM after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. November runs 86.4% on time and August 55.0%, a swing of 31 points. If the dates move at all, move them out of August before you think about anything else. 1,232 completed flights over 12 months sit behind that.
Common questions
DEN to BHM questions
How often is DEN to BHM delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.5% of the 1,236 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on DEN to BHM?
SkyWest Airlines leads at 79.2% on time across 604 flights. Southwest Airlines is at the other end on 63.3%, a gap of 16 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on DEN to BHM?
The 11am–2pm departure window is the strongest at 81.8% on time. The 8pm–5am window is the weakest at 55.8%, 26 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on DEN to BHM?
August is the weakest month at 55.0% on time, compared with 86.4% in November. Across the year that is 31 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- BHM to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- SkyWest Airlines on DEN to BHM79.2%
- United Airlines on DEN to BHM77.2%
- Southwest Airlines on DEN to BHM63.3%
- DEN to PHX, a related route75.6%
- ATL to BHM, a related route83.1%
- DEN to SLC, a related route78.2%
- SkyWest Airlines on-time record79.2%
- United Airlines on-time record77.2%
- Southwest Airlines on-time record63.3%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. DEN to BHM and BHM to DEN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.