Route reliability record

PHX→IAH

Phoenix to Houston

Flights: 2,927
Period: July 2025 to June 2026
Distance: 1,009 mi
Carriers: 5

This route lands a B+, 4 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 2,927 flights, of which United Airlines flew 1,780 at 84.6% on time.

The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

81.3%

Arrivals under 15 minutes late, of 2,887 completed flights

Avg delay

75 min

Across delayed arrivals only, not all flights

Cancelled

0.92%

National rate is 1.81%

Best carrier

United

84.6% on time across 1,780 flights

These figures cover 2,927 flights between July 2025 and June 2026. The median arrival is 5 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 PHX to IAH

The choice of carrier is not cosmetic here. United Airlines arrives on time 84.6% of the time; American Airlines manages 75.3%. Sample sizes sit next to every figure, because a two-point gap across 622 flights means less than a ten-point one.

On-time performance by carrier on PHX to IAH
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	1,780	84.6%	84 min	0.56%	B+
Envoy Airthin sample	68	81.8%	29 min	0.00%	B+
Frontier Airlinesthin sample	277	78.5%	62 min	1.08%	B
American Airlines	622	75.3%	68 min	1.45%	B
SkyWest Airlinesthin sample	180	72.6%	81 min	2.78%	C

United leads American 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 21 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am451 flights91.3%
8am–11am908 flights83.6%
11am–2pm638 flights82.0%
2pm–5pm407 flights75.1%
5pm–8pm426 flights70.5%
8pm–5am97 flights80.9%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 91.3% of the time, against 70.5% for the evening window. That is 21 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 908 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 16 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.

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

July is the worst month at 74.0% on time, 16 points below February, the best at 90.1%. 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 301 flights.

Across the week, Wednesday is the strongest day at 86.0% on time and Sunday the weakest at 76.1%. 10 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 41,000 reported delay minutes.

Late-arriving aircraft
39%
Carrier
34%
National Airspace System
25%
Extreme weather
2%

39% 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 41,000 reported delay minutes here, that single category outweighs weather by 18 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 40,806 reported delay minutes.

The largest share of delay minutes, 34%, 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 14,000 of the 41,000 delay minutes reported here.

Cancellations sit at 0.92% against a national 1.81%, which is ordinary. Diversions add another 0.44%.

Connections and stage length

What a delay here actually costs

6.8% of arrivals land an hour or more late, close to the national 8.1%. 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 a little over an hour kind, which a normal layover absorbs.

The 1,009 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 78.7% on time across 2,930 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 2,927 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. February runs 90.1% on time and July 74.0%, a swing of 16 points. If the dates move at all, move them out of July before you think about anything else. 2,887 completed flights over 12 months sit behind that.

Common questions

PHX to IAH questions

How often is PHX to IAH delayed?

About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.7% of the 2,927 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

Which airline is most reliable on PHX to IAH?

United Airlines leads at 84.6% on time across 1,780 flights. American Airlines is at the other end on 75.3%, 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 PHX to IAH?

The 5am–8am departure window is the strongest at 91.3% on time. The 5pm–8pm window is the weakest at 70.5%, 21 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 July delays on PHX to IAH?

July is the weakest month at 74.0% on time, compared with 90.1% in February. Across the year that is 16 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. PHX to IAH and IAH to PHX 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, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures