Carrier route record
UADEN→SAT
United Airlines · Denver to San Antonio
- Flights
- 1,205
- Period
- July 2025 to June 2026
- Share of route
- 40%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on DEN to SAT lands a B+, 4 points better than the national rate of 77.6%. About one flight in six arrives 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 1,205 flights. The strongest carrier on the route with a full sample, Frontier Airlines, flew 372 at 81.4% on time.
Set against the rest of the country, United's DEN to SAT record is 4 points better than the US average of 77.6%. That gap is worth roughly 43 fewer late arrivals for every thousand flights.
Key figures
On time
81.9%
Arrivals under 15 minutes late, of 1,201 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.25%
National rate is 1.81%
Whole route
76.5%
Every carrier on DEN to SAT, 3,030 flights
These figures cover 1,205 flights between July 2025 and June 2026. The median arrival is 6 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 DEN to SAT
United flew 1,205 of the 3,030 flights on DEN to SAT, about 40% of it. Its 81.9% on time is 5 points better than the route as a whole, which runs 76.5%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 81.9% to Southwest at 70.7%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. Frontier Airlines arrives on time 81.4% of the time; Southwest Airlines manages 70.7%. Sample sizes sit next to every figure, because a two-point gap across 1,434 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 1,205 | 81.9% | 63 min | 0.25% | B+ |
| Frontier Airlines | 372 | 81.4% | 60 min | 0.27% | B+ |
| SkyWest Airlinesthin sample | 19 | 78.9% | 192 min | 0.00% | B+ |
| Southwest Airlines | 1,434 | 70.7% | 52 min | 0.21% | C+ |
Frontier leads Southwest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
United flight numbers on DEN to SAT
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 29 points, against 11 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am364 flights90.4%
- 11am–2pm364 flights88.7%
- 2pm–5pm—
- 5pm–8pm364 flights72.9%
- 8pm–5am113 flights61.6%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 61.6% on time, against 90.4% for the 8am–11am 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 8am–11am window is the busiest, with 364 flights scheduled in it.
Across the year
United on DEN to SAT through the year
July is the worst month at 58.9% on time, 36 points below October, the best at 94.6%. 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. July was the busiest month here, with 124 flights.
Across the week, Wednesday is the strongest day at 86.5% on time and Sunday the weakest at 76.7%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 56% of the 14,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 56%Late-arriving aircraft
- 26%Carrier
- 16%National Airspace System
- 1%Extreme weather
56% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 14,000 reported delay minutes here, that single category outweighs weather by 44 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 13,577 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 90.4% on time here.
Cancellations are rare at 0.25%, 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
6.7% 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 last about an hour, which a normal layover absorbs.
The 794 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 runs 81.6% on time across 1,207 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 1,205 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 United on DEN to SAT
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 94.6% on time and July 58.9%, a swing of 36 points. If the dates move at all, move them out of July before you think about anything else. 1,201 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to SAT, every carrier
- United on SAT to DEN, the return leg
- Frontier Airlines on DEN to SAT81.4%
- Southwest Airlines on DEN to SAT70.7%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- San Antonio International (SAT) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.