Carrier route record
UAORD→IAH
United Airlines · Chicago to Houston
- Flights
- 4,000
- Period
- July 2025 to June 2026
- Share of route
- 66%
- Carriers
- 8
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on ORD to IAH lands a B+, about a point better than the national rate of 77.6%. About one flight in five 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 4,000 flights, with a median arrival 7 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate United on ORD to IAH from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.6%
Arrivals under 15 minutes late, of 3,965 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
0.65%
National rate is 1.81%
Whole route
75.0%
Every carrier on ORD to IAH, 6,077 flights
These figures cover 4,000 flights between July 2025 and June 2026. The median arrival is 7 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 ORD to IAH
United flew 4,000 of the 6,077 flights on ORD to IAH, most of the route. Its 78.6% on time is 4 points better than the route as a whole, which runs 75.0%. Ranked by on-time rate it is first of eight carriers on the route, where the range runs from United at 78.6% to SkyWest at 0.0%. Six 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 |
|---|---|---|---|---|---|
| United Airlines (this page) | 4,000 | 78.6% | 67 min | 0.65% | B+ |
| Republic Airwaysthin sample | 359 | 76.3% | 69 min | 2.51% | B |
| Frontier Airlinesthin sample | 249 | 76.0% | 96 min | 2.41% | B |
| Envoy Airthin sample | 358 | 74.4% | 63 min | 1.40% | C |
| Spirit Airlinesthin sample | 307 | 63.1% | 102 min | 5.54% | D− |
| American Airlines | 798 | 60.6% | 84 min | 3.01% | D− |
| PSA Airlinesthin sample | 4 | 50.0% | 74 min | 0.00% | F+ |
| SkyWest Airlinesthin sample | 2 | 0.0% | 32 min | 0.00% | F+ |
Flight by flight
United flight numbers on ORD 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 22 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–8am766 flights90.8%
- 8am–11am730 flights85.2%
- 11am–2pm384 flights85.7%
- 2pm–5pm845 flights72.6%
- 5pm–8pm660 flights68.8%
- 8pm–5am615 flights69.8%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.8% of the time, against 68.8% for the evening window. That is 22 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 845 flights scheduled in it.
Across the year
United on ORD to IAH through the year
July is the worst month at 65.1% on time, 26 points below February, the best at 91.2%. 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. December was the busiest month here, with 353 flights.
Across the week, Tuesday is the strongest day at 82.4% on time and Sunday the weakest at 74.6%. 8 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 42% of the 57,000 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.
- 42%Late-arriving aircraft
- 26%National Airspace System
- 25%Carrier
- 7%Extreme weather
42% 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 57,000 reported delay minutes here, that single category outweighs weather by 6 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 56,573 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 90.8% on time here.
Cancellations are rare at 0.65%, 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
7.4% 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 925 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 78.2% on time across 4,007 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 4,000 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 ORD to IAH
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 91.2% on time and July 65.1%, a swing of 26 points. If the dates move at all, move them out of July before you think about anything else. 3,965 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to IAH, every carrier
- United on IAH to ORD, the return leg
- Republic Airways on ORD to IAH76.3%
- Frontier Airlines on ORD to IAH76.0%
- Envoy Air on ORD to IAH74.4%
- Spirit Airlines on ORD to IAH63.1%
- American Airlines on ORD to IAH60.6%
- United Airlines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.