Carrier route record
UAIAH→SAT
United Airlines · Houston to San Antonio
- Flights
- 2,247
- Period
- September 2025 to August 2026
- Share of route
- 95%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to SAT lands a B+, 6 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 about an hour on average. That rests on 2,247 flights, with a median arrival 9 minutes early.
Set against the rest of the country, United's IAH to SAT record is 6 points better than the US average of 77.3%. That gap is worth roughly 57 fewer late arrivals for every thousand flights.
Key figures
On time
83.0%
Arrivals under 15 minutes late, of 2,238 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.36%
National rate is 1.89%
Whole route
83.1%
Every carrier on IAH to SAT, 2,373 flights
These figures cover 2,247 flights between September 2025 and August 2026. The median arrival is 9 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
United against every carrier on IAH to SAT
United flew 2,247 of the 2,373 flights on IAH to SAT, most of the route. Its 83.0% on time is about level with the route as a whole at 83.1%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 84.0% to United at 83.0%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 126 | 84.0% | 71 min | 0.79% | B+ |
| United Airlines (this page) | 2,247 | 83.0% | 58 min | 0.36% | B+ |
Flight by flight
United flight numbers on IAH to SAT
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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 20 points, against half a point between the best and worst carrier.
- 5am–8am291 flights93.1%
- 8am–11am267 flights86.9%
- 11am–2pm259 flights89.1%
- 2pm–5pm439 flights84.3%
- 5pm–8pm371 flights73.0%
- 8pm–5am620 flights79.2%
Scale runs 65% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.1% of the time, against 73.0% for the evening window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 620 flights scheduled in it.
Across the year
United on IAH to SAT through the year
June is the worst month at 69.3% on time, 22 points below February, the best at 91.6%. 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. September was the busiest month here, with 226 flights.
Across the week, Tuesday is the strongest day at 86.4% on time and Monday the weakest at 78.7%, a spread of 8 points.
Arrival by arrival
How late United on IAH to SAT runs when it is late
United on IAH to SAT often beats the schedule: 643 of 2,238 completed flights, 29%, arrived 15 minutes or more early. The 380 late arrivals split 159 under half an hour, 104 between 30 and 60 minutes, and 117 an hour or more.
- 15+ min early643 flights28.7%
- Within 15 min1,215 flights54.3%
- 15–29 min late159 flights7.1%
- 30–59 min late104 flights4.6%
- 1–2 hours late73 flights3.3%
- 2+ hours late44 flights2.0%
Scale runs 0% to 100%.
Share of 2,238 completed flights by arrival against schedule.
67 of 382 late departures made up the time and arrived on time, 18% of them. 65 flights left on time and still arrived late.
The worst days
Worst days for United on IAH to SAT
The latest arrival of the period was on 7 March 2026, 7 hours 42 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 March 2026 | 7 hours 42 minutes | Carrier |
| 25 October 2025 | 6 hours 32 minutes | Extreme weather |
| 11 June 2026 | 5 hours 37 minutes | Late-arriving aircraft |
| 9 November 2025 | 5 hours 24 minutes | Late-arriving aircraft |
| 19 June 2026 | 4 hours 13 minutes | Late-arriving aircraft |
Delay causes
Why United runs late on this route
Late-arriving aircraft accounts for 46% of the 22,000 delay minutes carriers reported here, and the remaining four split what is left.
- 46%Late-arriving aircraft
- 36%Carrier
- 12%National Airspace System
- 6%Extreme weather
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 22,000 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 21,941 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 7,914 of the 22,000 delay minutes reported here.
Cancellations are rare at 0.36%, 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 costs
5.2% 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 about an hour, which a normal layover absorbs.
At 191 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg runs 82.8% on time across 2,245 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 2,247 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 IAH to SAT
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 91.6% on time and June 69.3%, a swing of 22 points. If the dates move at all, move them out of June before you think about anything else. 2,238 completed flights over 12 months sit behind that.
Related
Where to go next
- IAH to SAT, every carrier
- United on SAT to IAH, the return leg
- SkyWest Airlines on IAH to SAT84.0%
- United Airlines network-wide record
- George Bush Intercontinental (IAH) delay statistics
- San Antonio International (SAT) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.