Carrier route record
UATUS→DEN
United Airlines · Tucson to Denver
- Flights
- 836
- Period
- July 2025 to June 2026
- Share of route
- 30%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on TUS to DEN earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 836 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 621 at 86.5% on time.
Set against the rest of the country, United's TUS to DEN record is 7 points better than the US average of 77.6%. That gap is worth roughly 71 fewer late arrivals for every thousand flights.
Key figures
On time
84.7%
Arrivals under 15 minutes late, of 829 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
0.60%
National rate is 1.81%
Whole route
82.9%
Every carrier on TUS to DEN, 2,754 flights
These figures cover 836 flights between July 2025 and June 2026. The median arrival is 8 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
United against every carrier on TUS to DEN
United flew 836 of the 2,754 flights on TUS to DEN, about 30% of it. Its 84.7% on time is 2 points better than the route as a whole, which runs 82.9%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from SkyWest at 86.5% to Southwest at 80.1%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 86.5% of the time; Southwest Airlines manages 80.1%. Sample sizes sit next to every figure, because a two-point gap across 1,202 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 621 | 86.5% | 93 min | 0.64% | A+ |
| United Airlines (this page) | 836 | 84.7% | 73 min | 0.60% | B+ |
| Frontier Airlinesthin sample | 95 | 80.9% | 52 min | 1.05% | B |
| Southwest Airlines | 1,202 | 80.1% | 61 min | 0.58% | B+ |
SkyWest leads Southwest by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 15 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am293 flights92.8%
- 8am–11am1 flights—
- 11am–2pm221 flights77.4%
- 2pm–5pm201 flights79.9%
- 5pm–8pm120 flights85.8%
- 8pm–5am—
Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 77.4% on time against 92.8% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5am–8am window is the busiest, with 293 flights scheduled in it.
Across the year
United on TUS to DEN through the year
July is the worst month at 50.0% on time, 42 points below April, the best at 91.7%. 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. October was the busiest month here, with 93 flights.
Across the week, Sunday is the strongest day at 89.1% on time and Friday the weakest at 80.7%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
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 9,294 reported delay minutes.
- 31%Carrier
- 30%Late-arriving aircraft
- 30%National Airspace System
- 9%Extreme weather
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 92.8% on time here. The split is drawn from 9,294 reported delay minutes.
No single cause dominates. carrier at 31%, late-arriving aircraft at 30% and national airspace system at 30% split the 9,294 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 0.60%, below the national 1.81% 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 costs
6.0% 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 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. 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 80.6% on time across 836 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.
One caution: this is a thin sample. 836 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 United on TUS to DEN
Put together: treat all of this as provisional. 836 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 84.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 829 completed flights over 12 months sit behind that.
Related
Where to go next
- TUS to DEN, every carrier
- United on DEN to TUS, the return leg
- SkyWest Airlines on TUS to DEN86.5%
- Southwest Airlines on TUS to DEN80.1%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- 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
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.