Carrier route record

UAIAH→LAX

United Airlines · Houston to Los Angeles

Flights: 3,416
Period: July 2025 to June 2026
Share of route: 65%
Carriers: 6

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

United on IAH to LAX 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 about an hour. That rests on 3,416 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 645 at 88.5% on time.

Delta Air Lines is the most reliable of the three carriers covered here at 88.5% on time across 645 flights.

On time

84.4%

Arrivals under 15 minutes late, of 3,401 completed flights

Avg delay

59 min

Across delayed arrivals only, not all flights

Cancelled

0.32%

National rate is 1.81%

Whole route

83.6%

Every carrier on IAH to LAX, 5,260 flights

These figures cover 3,416 flights between July 2025 and June 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.

Carrier by carrier

United against every carrier on IAH to LAX

United flew 3,416 of the 5,260 flights on IAH to LAX, most of the route. Its 84.4% on time is about level with the route as a whole at 83.6%. Ranked by on-time rate it is number three of six carriers on the route, where the range runs from American at 100.0% to Frontier at 72.6%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 88.5% of the time; SkyWest Airlines manages 78.3%. Sample sizes sit next to every figure, because a two-point gap across 408 flights means less than a ten-point one.

On-time performance by carrier on IAH to LAX
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlinesthin sample	1	100.0%	—	0.00%	A+
Delta Air Lines	645	88.5%	86 min	1.09%	A
United Airlines (this page)	3,416	84.4%	59 min	0.32%	B+
Spirit Airlines	458	83.6%	70 min	1.31%	B
SkyWest Airlines	408	78.3%	75 min	0.49%	B+
Frontier Airlinesthin sample	332	72.6%	60 min	1.20%	C

Delta leads SkyWest by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

United flight numbers on IAH to LAX

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 18 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am751 flights94.3%
8am–11am365 flights87.1%
11am–2pm365 flights87.4%
2pm–5pm725 flights83.7%
5pm–8pm381 flights79.2%
8pm–5am829 flights76.0%

Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 94.3% of the time, against 76.0% for the overnight window. That is 18 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 829 flights scheduled in it.

Across the year

United on IAH to LAX through the year

Darker means more delays. Figures are on-time percentages.January best, July worst

July is the worst month at 75.7% on time, 16 points below January, 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. May was the busiest month here, with 303 flights.

Across the week, Wednesday is the strongest day at 87.7% on time and Saturday the weakest at 79.7%. 8 points is a smaller lever than departure hour, but it is free.

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 31,000 reported delay minutes.

Carrier
39%
Late-arriving aircraft
35%
National Airspace System
17%
Extreme weather
9%

35% 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 31,000 reported delay minutes here, that single category outweighs weather by 4 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 31,264 reported delay minutes.

The largest share of delay minutes, 39%, 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 12,000 of the 31,000 delay minutes reported here.

Cancellations are rare at 0.32%, 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 4.9% 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.

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. 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 87.1% on time across 3,415 flights, within 3 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 3,416 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 LAX

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 91.2% on time and July 75.7%, a swing of 16 points. If the dates move at all, move them out of July before you think about anything else. 3,401 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures