Carrier route record
UASEA→IAH
United Airlines · Seattle to Houston
- Flights
- 1,243
- Period
- July 2025 to June 2026
- Share of route
- 59%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on SEA to IAH 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 1,243 flights, with a median arrival 10 minutes early.
Set against the rest of the country, United's SEA to IAH record is 7 points better than the US average of 77.6%. That gap is worth roughly 69 fewer late arrivals for every thousand flights.
Key figures
On time
84.5%
Arrivals under 15 minutes late, of 1,230 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.56%
National rate is 1.81%
Whole route
80.3%
Every carrier on SEA to IAH, 2,095 flights
These figures cover 1,243 flights between July 2025 and June 2026. The median arrival is 10 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 SEA to IAH
United flew 1,243 of the 2,095 flights on SEA to IAH, most of the route. Its 84.5% on time is 4 points better than the route as a whole, which runs 80.3%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 84.5% to Alaska at 74.3%.
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 |
|---|---|---|---|---|---|
| United Airlines (this page) | 1,243 | 84.5% | 70 min | 0.56% | B+ |
| Alaska Airlines | 852 | 74.3% | 45 min | 0.70% | C+ |
Flight by flight
United flight numbers on SEA to IAH
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 14 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am449 flights89.4%
- 8am–11am67 flights89.6%
- 11am–2pm199 flights75.8%
- 2pm–5pm121 flights82.6%
- 5pm–8pm119 flights83.8%
- 8pm–5am288 flights82.7%
Scale runs 65% to 95%. 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 75.8% on time against 89.6% for 8am–11am. 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 449 flights scheduled in it.
Across the year
United on SEA to IAH through the year
July is the worst month at 69.6% on time, 29 points below February, the best at 98.2%. 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 144 flights.
Across the week, Wednesday is the strongest day at 90.2% on time and Saturday the weakest at 80.8%. 9 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. Carrier accounts for 47% of the 13,000 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.
- 47%Carrier
- 31%Late-arriving aircraft
- 21%National Airspace System
- 1%Extreme weather
- 0%Security
The largest share of delay minutes, 47%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 6,216 of the 13,000 delay minutes reported here. The split is drawn from 13,348 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 89.6% on time here.
Cancellations are rare at 0.56%, 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
Badly late arrivals are rare here: only 4.4% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 1,874 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 76.8% on time across 1,243 flights, 8 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 8 points of difference.
The sample behind these figures is 1,243 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 SEA to IAH
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 98.2% on time and July 69.6%, a swing of 29 points. If the dates move at all, move them out of July before you think about anything else. 1,230 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to IAH, every carrier
- United on IAH to SEA, the return leg
- Alaska Airlines on SEA to IAH74.3%
- United Airlines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- George Bush Intercontinental (IAH) 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.