Route reliability record
SAT→DEN
San Antonio to Denver
- Flights
- 3,063
- Period
- September 2025 to August 2026
- Distance
- 794 mi
- Carriers
- 4
This route lands a B+, 5 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 3,063 SAT to DEN flights, of which United Airlines flew 1,197 at 83.4% on time.
Best time to fly SAT to DEN: a 5am–8am departure, ideally on a Sunday. Flights in that window arrived on time 94.9% of the time and Sunday flights 85.5%, against 82.1% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 83.4% on time across 1,197 flights.
Key figures
On time
82.1%
Arrivals under 15 minutes late, of 3,037 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
0.52%
National rate is 1.89%
Best carrier
United
83.4% on time across 1,197 flights
These figures cover 3,063 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on SAT to DEN
The three carriers here are closely matched: 2 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 39 | 92.3% | 213 min | 0.00% | A+ |
| United Airlines | 1,197 | 83.4% | 79 min | 0.67% | B+ |
| Frontier Airlines | 394 | 81.3% | 92 min | 0.51% | B+ |
| Southwest Airlines | 1,433 | 81.0% | 54 min | 0.42% | B+ |
No carrier stands out. United tops the table at 83.4%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on SAT to DEN
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 San Antonio 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. SAT → DENSan Antonio to Denver | United Airlines | 82.8% | 83.4% | 0.67% | 5am–8am, Sun | UA 2853 08:53 |
| 2. SAT → DENSan Antonio to Denver | Frontier Airlines | 80.9% | 81.3% | 0.51% | 8am–11am, Thu | — |
| 3. SAT → DENSan Antonio to Denver | Southwest Airlines | 80.7% | 81.0% | 0.42% | 5am–8am, Wed | — |
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 31 points, against 2 points between the best and worst carrier.
- 5am–8am580 flights94.9%
- 8am–11am586 flights87.0%
- 11am–2pm716 flights85.2%
- 2pm–5pm570 flights75.7%
- 5pm–8pm408 flights64.0%
- 8pm–5am203 flights75.2%
Scale runs 55% to 100%.
The 5pm–8pm window is where this operation falls apart: 64.0% on time, against 94.9% for the 5am–8am 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 11am–2pm window is the busiest, with 716 flights scheduled in it.
Explore
Filter SAT 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 SAT to DEN, the best departure window is 5am–8am at 94.9% on time and the worst is 5pm–8pm at 64.0%, a wide gap of 30.9 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.9%
- 8–11am87.0%
- 11am–2pm85.2%
- 2–5pm75.7%
- 5–8pm64.0%
- 8pm–5am75.2%
best all US flightsScale 55% to 100%.
Across the year
When delays peak on this route
This route's year swings by 19 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.
June is the worst month at 69.4% on time, 19 points below January, the best at 88.1%. 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 295 flights.
Across the week, Sunday is the strongest day at 85.5% on time and Monday the weakest at 79.6%, 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 38,000 reported delay minutes.
- 40%Late-arriving aircraft
- 30%National Airspace System
- 28%Carrier
- 2%Extreme weather
- 0%Security
40% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 38,000 reported delay minutes here, that single category outweighs weather by 24 to one. The split is drawn from 37,552 reported delay minutes.
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 94.9% on time here.
Cancellations are rare at 0.52%, 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
6.4% 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 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.
The return leg is a different operation and performs like one: it runs 76.8% on time across 3,067 flights, 5 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 5 points of difference.
The sample behind these figures is 3,063 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. January runs 88.1% on time and June 69.4%, a swing of 19 points. If the dates move at all, move them out of June before you think about anything else. 3,037 completed flights over 12 months sit behind that.
Common questions
SAT to DEN questions
How often is SAT 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 17.9% of the 3,063 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 SAT to DEN?
United Airlines leads at 83.4% on time across 1,197 flights. Southwest Airlines is at the other end on 81.0%, a gap of 2 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 SAT to DEN?
The 5am–8am departure window is the strongest at 94.9% on time. The 5pm–8pm window is the weakest at 64.0%, 31 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 June delays on SAT to DEN?
June is the weakest month at 69.4% on time, compared with 88.1% in January. Across the year that is 19 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 SAT — the return legseparate record
- San Antonio International (SAT) delay statistics
- Denver International (DEN) delay statistics
- United Airlines on SAT to DEN83.4%
- Frontier Airlines on SAT to DEN81.3%
- Southwest Airlines on SAT to DEN81.0%
- SAT to DFW, a related route79.4%
- PHX to DEN, a related route76.7%
- SAT to ATL, a related route85.9%
- SkyWest Airlines on-time record92.3%
- United Airlines on-time record83.4%
- Frontier Airlines on-time record81.3%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SAT to DEN and DEN to SAT 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.