Route reliability record
TUS→DEN
Tucson to Denver
- Flights
- 2,719
- Period
- September 2025 to August 2026
- Distance
- 639 mi
- Carriers
- 4
This route lands a B+, 7 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 2,719 TUS to DEN flights, of which SkyWest Airlines flew 522 at 89.0% on time.
Best time to fly TUS to DEN: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 94.2% of the time and Saturday flights 87.3%, against 83.9% for the route overall.
SkyWest Airlines is the most reliable of the three carriers covered here at 89.0% on time across 522 flights.
Key figures
On time
83.9%
Arrivals under 15 minutes late, of 2,698 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
0.59%
National rate is 1.89%
Best carrier
SkyWest
89.0% on time across 522 flights
These figures cover 2,719 flights between September 2025 and August 2026. The median arrival is 7 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
Which airline is most reliable on TUS to DEN
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 89.0% of the time; Southwest Airlines manages 79.9%. Sample sizes sit next to every figure, because a two-point gap across 1,197 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 522 | 89.0% | 109 min | 0.57% | A+ |
| United Airlines | 923 | 86.2% | 78 min | 0.54% | A+ |
| Frontier Airlinesthin sample | 77 | 82.9% | 53 min | 1.30% | B |
| Southwest Airlines | 1,197 | 79.9% | 62 min | 0.58% | B+ |
SkyWest leads Southwest by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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Best ways to make this trip
The most reliable ways to fly Tucson to Denver
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. TUS → DENTucson to Denver | SkyWest Airlines | 88.5% | 89.0% | 0.57% | 5am–8am, Sat | — |
| 2. TUS → DENTucson to Denver | United Airlines | 85.7% | 86.2% | 0.54% | 5am–8am, Sun | — |
| 3. TUS → DENTucson to Denver | Southwest Airlines | 79.4% | 79.9% | 0.58% | 5am–8am, Sat | — |
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 25 points, against 9 points between the best and worst carrier.
- 5am–8am776 flights94.2%
- 8am–11am687 flights87.5%
- 11am–2pm483 flights81.0%
- 2pm–5pm607 flights69.6%
- 5pm–8pm166 flights81.3%
- 8pm–5am—
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 94.2% of the time, against 69.6% for the afternoon window. That is 25 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 776 flights scheduled in it.
Explore
Filter TUS to DEN 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 TUS to DEN, the best departure window is 5am–8am at 94.2% on time and the worst is 2pm–5pm at 69.6%, a wide gap of 24.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.2%
- 8–11am87.5%
- 11am–2pm81.0%
- 2–5pm69.6%
- 5–8pm81.3%
- 8pm–5am—
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 14 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 76.7% on time, 14 points below November, the best at 90.6%. 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. March was the busiest month here, with 275 flights.
Across the week, Saturday is the strongest day at 87.3% on time and Monday the weakest at 81.4%, a spread of 6 points.
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%Carrier
- 31%National Airspace System
- 31%Late-arriving aircraft
- 4%Extreme weather
- 0%Security
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 94.2% on time here. The split is drawn from 31,423 reported delay minutes.
No single cause dominates. carrier at 34%, national airspace system at 31% and late-arriving aircraft at 31% split the 31,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around.
Cancellations are rare at 0.59%, 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
5.9% 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 a little over an hour, which a normal layover absorbs.
The 639 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 76.9% on time across 2,708 flights, 7 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 7 points of difference.
The sample behind these figures is 2,719 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 DEN 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 90.6% on time and July 76.7%, a swing of 14 points. If the dates move at all, move them out of July before you think about anything else. 2,698 completed flights over 12 months sit behind that.
Common questions
TUS to DEN questions
How often is TUS to DEN delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.1% of the 2,719 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on TUS to DEN?
SkyWest Airlines leads at 89.0% on time across 522 flights. Southwest Airlines is at the other end on 79.9%, a gap of 9 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 TUS to DEN?
The 5am–8am departure window is the strongest at 94.2% on time. The 2pm–5pm window is the weakest at 69.6%, 25 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 TUS to DEN?
July is the weakest month at 76.7% on time, compared with 90.6% in November. Across the year that is 14 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 TUS — the return legseparate record
- Denver International (DEN) delay statistics
- SkyWest Airlines on TUS to DEN89.0%
- United Airlines on TUS to DEN86.2%
- Southwest Airlines on TUS to DEN79.9%
- TUS to PHX, a related route83.6%
- PHX to DEN, a related route76.7%
- TUS to LAX, a related route86.4%
- SkyWest Airlines on-time record89.0%
- United Airlines on-time record86.2%
- Frontier Airlines on-time record82.9%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. TUS to DEN and DEN to TUS 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.