Route reliability record
TUL→DEN
Tulsa to Denver
- Flights
- 2,430
- Period
- July 2025 to June 2026
- Distance
- 541 mi
- Carriers
- 4
This route lands a B+, 2 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 2,430 flights, of which Southwest Airlines flew 893 at 82.4% on time.
Southwest Airlines is the most reliable of the three carriers covered here at 82.4% on time across 893 flights.
Key figures
On time
79.8%
Arrivals under 15 minutes late, of 2,401 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.99%
National rate is 1.81%
Best carrier
Southwest
82.4% on time across 893 flights
These figures cover 2,430 flights between July 2025 and June 2026. The median arrival is 5 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.
Carrier by carrier
Which airline is most reliable on TUL to DEN
The choice of carrier is not cosmetic here. Southwest Airlines arrives on time 82.4% of the time; United Airlines manages 75.7%. Sample sizes sit next to every figure, because a two-point gap across 366 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines | 893 | 82.4% | 59 min | 1.12% | B |
| SkyWest Airlines | 1,129 | 79.2% | 74 min | 0.89% | B+ |
| United Airlines | 366 | 75.7% | 45 min | 1.09% | B |
| Frontier Airlinesthin sample | 42 | 73.8% | 64 min | 0.00% | C+ |
Southwest leads United by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 27 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am639 flights93.2%
- 8am–11am486 flights78.6%
- 11am–2pm498 flights81.6%
- 2pm–5pm30 flights—
- 5pm–8pm631 flights66.1%
- 8pm–5am146 flights77.2%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.2% of the time, against 66.1% for the evening window. That is 27 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 639 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 24 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.
July is the worst month at 65.6% on time, 24 points below January, the best at 89.8%. 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. June was the busiest month here, with 228 flights.
Across the week, Friday is the strongest day at 83.0% on time and Monday the weakest at 77.8%. 5 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 31,000 reported delay minutes.
- 34%National Airspace System
- 31%Carrier
- 26%Late-arriving aircraft
- 9%Extreme weather
34% 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 11,000 minutes out of 31,000, against a national NAS share of 21%. The split is drawn from 31,003 reported delay minutes.
Cancellations sit at 0.99% against a national 1.81%, which is ordinary. Diversions add another 0.21%.
Connections and stage length
What a delay here actually costs
6.7% 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 are the about an hour kind, which a normal layover absorbs.
The 541 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 76.1% on time across 2,432 flights, 4 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 4 points of difference.
The sample behind these figures is 2,430 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.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 89.8% on time and July 65.6%, a swing of 24 points. If the dates move at all, move them out of July before you think about anything else. 2,401 completed flights over 12 months sit behind that.
Common questions
TUL to DEN questions
How often is TUL to DEN delayed?
About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.2% of the 2,430 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on TUL to DEN?
Southwest Airlines leads at 82.4% on time across 893 flights. United Airlines is at the other end on 75.7%, a gap of 7 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 TUL to DEN?
The 5am–8am departure window is the strongest at 93.2% on time. The 5pm–8pm window is the weakest at 66.1%, 27 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 July delays on TUL to DEN?
July is the weakest month at 65.6% on time, compared with 89.8% in January. Across the year that is 24 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
- DEN to TUL — the return legseparate record
- Denver International (DEN) delay statistics
- Southwest Airlines on-time record82.4%
- SkyWest Airlines on-time record79.2%
- United Airlines on-time record75.7%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. TUL to DEN and DEN to TUL are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.