Carrier route record

DLIAH→LAX

Delta Air Lines · Houston to Los Angeles

Flights: 648
Period: September 2025 to August 2026
Share of route: 13%
Carriers: 6

Historical statistics for September 2025 to August 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 10 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 648 flights. The strongest carrier on the route with a full sample, United Airlines, flew 3,421 at 85.7% on time.

Set against the rest of the country, Delta's IAH to LAX record is 10 points better than the US average of 77.3%. That gap is worth roughly 104 fewer late arrivals for every thousand flights.

On time

87.7%

Arrivals under 15 minutes late, of 642 completed flights

Avg delay

70 min

Across delayed arrivals only, not all flights

Cancelled

0.93%

National rate is 1.89%

Whole route

84.1%

Every carrier on IAH to LAX, 5,147 flights

These figures cover 648 flights between September 2025 and August 2026. The median arrival is 11 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

Delta against every carrier on IAH to LAX

Delta flew 648 of the 5,147 flights on IAH to LAX, about 13% of it. Its 87.7% on time is 4 points better than the route as a whole, which runs 84.1%. 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 71.8%. Three 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 85.7% of the time; SkyWest Airlines manages 79.3%. 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)	648	87.7%	70 min	0.93%	A+
United Airlines	3,421	85.7%	57 min	0.20%	A+
SkyWest Airlines	408	79.3%	77 min	0.49%	B+
Spirit Airlinesthin sample	333	78.9%	71 min	1.50%	B
Frontier Airlinesthin sample	336	71.8%	60 min	0.89%	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 121607:0093.1% · 365 flights

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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.

5am–8am365 flights93.1%
8am–11am—
11am–2pm—
2pm–5pm283 flights80.6%
5pm–8pm—
8pm–5am—

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 93.1% of the time, against 80.6% 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, July worst

July is the worst month at 76.4% on time, 20 points below March, the best at 96.5%. 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. March was the busiest month here, with 58 flights.

Across the week, Wednesday is the strongest day at 92.6% on time and Sunday the weakest at 82.1%, a spread of 11 points.

Arrival by arrival

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

Delta on IAH to LAX often beats the schedule: 259 of 642 completed flights, 40%, arrived 15 minutes or more early. The 79 late arrivals split 33 under half an hour, 20 between 30 and 60 minutes, and 26 an hour or more.

15+ min early259 flights40.3%
Within 15 min304 flights47.4%
15–29 min late33 flights5.1%
30–59 min late20 flights3.1%
1–2 hours late14 flights2.2%
2+ hours late12 flights1.9%

Scale runs 0% to 100%.

Share of 642 completed flights by arrival against schedule.

24 of 83 late departures made up the time and arrived on time, 29% of them. 20 flights left on time and still arrived late.

The worst days

Worst days for Delta on IAH to LAX

The latest arrival of the period was on 23 December 2025, 6 hours 46 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.

The latest arrivals of Delta on IAH to LAX in the period
Date	Arrived late by	Largest filed cause
23 December 2025	6 hours 46 minutes	Late-arriving aircraft
23 January 2026	5 hours 23 minutes	Carrier
19 June 2026	5 hours 20 minutes	Late-arriving aircraft
22 May 2026	4 hours 14 minutes	Late-arriving aircraft
12 July 2026	4 hours 8 minutes	Carrier

Delay causes

Why Delta runs late on this route

Late-arriving aircraft accounts for 43% of the 5,533 delay minutes carriers reported here, and the remaining four split what is left.

Late-arriving aircraft
43%
Carrier
43%
National Airspace System
13%
Extreme weather
1%

43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 5,533 reported delay minutes here, that single category outweighs weather by 29 to one. The split is drawn from 5,533 reported delay minutes.

The largest share of delay minutes, 43%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,352 of the 5,533 delay minutes reported here.

Cancellations sit at 0.93% against a national 1.89%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 4.0% 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 84.8% on time across 648 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.

One caution: this is a thin sample. 648 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. 648 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 87.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 642 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