Route reliability record
IAH→LAX
Houston to Los Angeles
- Flights
- 5,294
- Period
- June 2025 to May 2026
- Distance
- 1,379 mi
- Carriers
- 5
This route lands a B+, 6 points better than the national rate of 77.4%. About one flight in six arrive 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 5,294 flights, of which Delta Air Lines flew 646 at 88.1% on time.
Delta Air Lines is the most reliable of the four carriers covered here at 88.1% on time across 646 flights.
Key figures
On time
83.0%
Arrivals under 15 minutes late, of 5,252 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
0.68%
National rate is 1.80%
Best carrier
Delta
88.1% on time across 646 flights
These figures cover 5,294 flights between June 2025 and May 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
Which airline is most reliable on IAH to LAX
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 88.1% of the time; SkyWest Airlines manages 78.8%. Sample sizes sit next to every figure, because a two-point gap across 409 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 646 | 88.1% | 89 min | 1.24% | A |
| United Airlines | 3,394 | 83.7% | 63 min | 0.41% | B+ |
| Spirit Airlines | 513 | 83.7% | 69 min | 1.56% | B |
| SkyWest Airlines | 409 | 78.8% | 77 min | 0.49% | B+ |
| Frontier Airlinesthin sample | 332 | 69.8% | 59 min | 1.20% | C |
Delta leads SkyWest by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 18 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,244 flights93.6%
- 8am–11am458 flights86.6%
- 11am–2pm522 flights81.7%
- 2pm–5pm1,246 flights82.2%
- 5pm–8pm674 flights75.5%
- 8pm–5am1,150 flights75.8%
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.6% of the time, against 75.5% for the evening 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.
Across the year
When delays peak on this route
This route's year swings by 15 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 71.7% on time, 15 points below September, the best at 86.6%. 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.
Across the week, Wednesday is the strongest day at 88.1% on time and Saturday the weakest at 80.1%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 60,000 reported delay minutes.
- 40%Carrier
- 34%Late-arriving aircraft
- 16%National Airspace System
- 9%Extreme weather
- 0%Security
The largest share of delay minutes, 40%, 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 24,000 of the 60,000 delay minutes reported here.
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 93.6% on time here.
Cancellations are rare at 0.68%, below the national 1.80% 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 actually costs
5.8% of arrivals land an hour or more late, close to the national 8.2%. 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 are the about an hour kind, which a normal layover absorbs.
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 84.0% on time across 5,291 flights, within about 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 5,294 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 86.6% on time and June 71.7%, a swing of 15 points. If the dates move at all, move them out of June before you think about anything else.
Common questions
IAH to LAX questions
How often is IAH to LAX delayed?
About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.0% of the 5,294 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on IAH to LAX?
Delta Air Lines leads at 88.1% on time across 646 flights. SkyWest Airlines is at the other end on 78.8%, a gap of 9 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on IAH to LAX?
The 5am–8am departure window is the strongest at 93.6% on time. The 5pm–8pm window is the weakest at 75.5%, 18 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on IAH to LAX?
June is the weakest month at 71.7% on time, compared with 86.6% in September. Across the year that is 15 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- LAX to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Los Angeles International (LAX) delay statistics
- Delta Air Lines on-time record88.1%
- United Airlines on-time record83.7%
- Spirit Airlines on-time record83.7%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. IAH to LAX and LAX to IAH are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.