Carrier route record

DLIAH→LAX

Delta Air Lines · Houston to Los Angeles

Flights: 645
Period: July 2025 to June 2026
Share of route: 12%
Carriers: 6

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

Delta on IAH to LAX 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 11 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 645 flights. The strongest carrier on the route with a full sample, United Airlines, flew 3,416 at 84.4% on time.

Set against the rest of the country, Delta's IAH to LAX record is 11 points better than the US average of 77.6%. That gap is worth roughly 109 fewer late arrivals for every thousand flights.

On time

88.5%

Arrivals under 15 minutes late, of 637 completed flights

Avg delay

86 min

Across delayed arrivals only, not all flights

Cancelled

1.09%

National rate is 1.81%

Whole route

83.6%

Every carrier on IAH to LAX, 5,260 flights

These figures cover 645 flights between July 2025 and June 2026. The median arrival is 12 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

Delta against every carrier on IAH to LAX

Delta flew 645 of the 5,260 flights on IAH to LAX, about 12% of it. Its 88.5% on time is 5 points better than the route as a whole, which runs 83.6%. Ranked by on-time rate it is number two 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. United Airlines arrives on time 84.4% 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 (this page)	645	88.5%	86 min	1.09%	A
United Airlines	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

United leads SkyWest by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

Delta flight numbers on IAH to LAX

DL 121607:0094.2% · 365 flights

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 13 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am365 flights94.2%
8am–11am—
11am–2pm—
2pm–5pm280 flights81.0%
5pm–8pm—
8pm–5am—

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 94.2% of the time, against 81.0% for the afternoon window. That is 13 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 365 flights scheduled in it.

Across the year

Delta on IAH to LAX through the year

Darker means more delays. Figures are on-time percentages.March best, December worst

December is the weak month at 80.4% on time, against 96.5% in March. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. March was the busiest month here, with 58 flights.

Across the week, Wednesday is the strongest day at 93.5% on time and Sunday the weakest at 84.0%. 10 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 55% of the 6,307 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.

Carrier
55%
Late-arriving aircraft
32%
National Airspace System
11%
Extreme weather
2%

The largest share of delay minutes, 55%, 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 3,461 of the 6,307 delay minutes reported here. The split is drawn from 6,307 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 94.2% on time here.

Cancellations sit at 1.09% against a national 1.81%, which is ordinary. Diversions add another 0.16%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 4.6% 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 86.1% on time across 645 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.

One caution: this is a thin sample. 645 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Delta on IAH to LAX

Put together: treat all of this as provisional. 645 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 88.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 637 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