Carrier route record

UALAX→IAH

United Airlines · Los Angeles to Houston

Flights: 3,420
Period: September 2025 to August 2026
Share of route: 66%
Carriers: 5

Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.

United on LAX to IAH earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 10 points better than the national rate of 77.3%. When something does go wrong the average delay runs roughly 50 minutes. That rests on 3,420 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 648 at 84.8% on time.

Set against the rest of the country, United's LAX to IAH record is 10 points better than the US average of 77.3%. That gap is worth roughly 101 fewer late arrivals for every thousand flights.

On time

87.4%

Arrivals under 15 minutes late, of 3,406 completed flights

Avg delay

52 min

Across delayed arrivals only, not all flights

Cancelled

0.18%

National rate is 1.89%

Whole route

84.6%

Every carrier on LAX to IAH, 5,143 flights

These figures cover 3,420 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 LAX to IAH

United flew 3,420 of the 5,143 flights on LAX to IAH, most of the route. Its 87.4% on time is 3 points better than the route as a whole, which runs 84.6%. Ranked by on-time rate it is first of five carriers on the route, where the range runs from United at 87.4% to Frontier at 70.6%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The two carriers here are closely matched: 4 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.

On-time performance by carrier on LAX to IAH
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines (this page)	3,420	87.4%	52 min	0.18%	A+
Delta Air Lines	648	84.8%	70 min	0.93%	B+
SkyWest Airlines	408	81.2%	70 min	0.49%	B+
Spirit Airlinesthin sample	331	73.0%	73 min	1.51%	C
Frontier Airlinesthin sample	336	70.6%	74 min	1.49%	C

No carrier stands out. Delta tops the table at 84.8%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.

Flight by flight

United flight numbers on LAX to IAH

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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 17 points, against 4 points between the best and worst carrier.

5am–8am668 flights95.1%
8am–11am739 flights90.4%
11am–2pm717 flights78.0%
2pm–5pm354 flights86.1%
5pm–8pm391 flights84.6%
8pm–5am551 flights89.4%

Scale runs 70% to 100%.

The weak window here is the middle of the day, not the evening: 11am–2pm runs 78.0% on time against 95.1% for 5am–8am. 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 8am–11am window is the busiest, with 739 flights scheduled in it.

Across the year

United on LAX to IAH through the year

Darker means more delays. Figures are on-time percentages.October best, November worst

October is the best month on the calendar at 94.0% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. May was the busiest month here, with 303 flights.

Across the week, Wednesday is the strongest day at 89.7% on time and Saturday the weakest at 84.8%, a spread of 5 points.

Arrival by arrival

How late United on LAX to IAH runs when it is late

United on LAX to IAH often beats the schedule: 1,046 of 3,406 completed flights, 31%, arrived 15 minutes or more early. The 428 late arrivals split 209 under half an hour, 113 between 30 and 60 minutes, and 106 an hour or more.

15+ min early1,046 flights30.7%
Within 15 min1,932 flights56.7%
15–29 min late209 flights6.1%
30–59 min late113 flights3.3%
1–2 hours late68 flights2.0%
2+ hours late38 flights1.1%

Scale runs 0% to 100%.

Share of 3,406 completed flights by arrival against schedule.

88 of 360 late departures made up the time and arrived on time, 24% of them. 156 flights left on time and still arrived late.

The worst days

Worst days for United on LAX to IAH

The latest arrival of the period was on 19 June 2026, 6 hours 6 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in March 2026.

The latest arrivals of United on LAX to IAH in the period
Date	Arrived late by	Largest filed cause
19 June 2026	6 hours 6 minutes	Carrier
9 March 2026	5 hours 19 minutes	Late-arriving aircraft
7 March 2026	5 hours	National Airspace System
16 March 2026	4 hours 36 minutes	Late-arriving aircraft
20 February 2026	4 hours 26 minutes	Carrier

Delay causes

Why United runs late on this route

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 22,000 reported delay minutes.

Carrier
38%
National Airspace System
31%
Late-arriving aircraft
30%
Extreme weather
2%

The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 8,385 of the 22,000 delay minutes reported here. The split is drawn from 22,043 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 95.1% on time here.

Cancellations are rare at 0.18%, 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

Badly late arrivals are rare here: only 3.1% land an hour or more behind schedule, against 8.3% 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.

The 1,379 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 runs 85.7% on time across 3,421 flights, within 2 points 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 3,420 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 LAX to IAH

Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 94.0% on time and November 79.9%, a swing of 14 points. If the dates move at all, move them out of November before you think about anything else. 3,406 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures