Route reliability record
PDX→IAH
Portland to Houston
- Flights
- 1,233
- Period
- July 2025 to June 2026
- Distance
- 1,825 mi
- Carriers
- 2
This route earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 8 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 1,233 PDX to IAH flights, with a median arrival 9 minutes early.
Best time to fly PDX to IAH: a 5am–8am departure, ideally on a Sunday. Flights in that window arrived on time 93.9% of the time and Sunday flights 88.6%, against 85.4% for the route overall.
Set against the rest of the country, this route's record is 8 points better than the US average of 77.6%. That gap is worth roughly 78 fewer late arrivals for every thousand flights.
Key figures
On time
85.4%
Arrivals under 15 minutes late, of 1,222 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
0.65%
National rate is 1.81%
Best carrier
United
86.4% on time across 880 flights
These figures cover 1,233 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
Which airline is most reliable on PDX to IAH
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 880 | 86.4% | 75 min | 0.57% | A+ |
| Alaska Airlinesthin sample | 353 | 83.1% | 44 min | 0.85% | B+ |
Flight by flight
Flights on PDX to IAH
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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 16 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am449 flights93.9%
- 8am–11am200 flights77.6%
- 11am–2pm337 flights79.5%
- 2pm–5pm96 flights81.2%
- 5pm–8pm—
- 8pm–5am151 flights86.6%
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 93.9% of the time, against 77.6% for the morning window. That is 16 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 449 flights scheduled in it.
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.
July is the worst month at 77.3% on time, 15 points below September, the best at 92.7%. 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. July was the busiest month here, with 123 flights.
Across the week, Sunday is the strongest day at 88.6% on time and Friday the weakest at 80.0%. 9 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 12,000 reported delay minutes.
- 35%National Airspace System
- 33%Late-arriving aircraft
- 31%Carrier
- 1%Extreme weather
- 1%Security
35% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 4,005 minutes out of 12,000, against a national NAS share of 21%. The split is drawn from 11,508 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 93.9% on time here.
Cancellations are rare at 0.65%, 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 actually costs
Badly late arrivals are rare here: only 4.4% 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.
At 1,825 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 81.1% on time across 1,233 flights, 4 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
The sample behind these figures is 1,233 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.
Work out the risk of missing a connection in IAH after this flight
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 92.7% on time and July 77.3%, a swing of 15 points. If the dates move at all, move them out of July before you think about anything else. 1,222 completed flights over 12 months sit behind that.
Common questions
PDX to IAH questions
How often is PDX to IAH delayed?
About one flight in seven arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 14.6% of the 1,233 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is PDX to IAH compared with the rest of the country?
85.4% of flights arrive on time here against a national 77.6%, a difference of 8 points in its favour. That is worth a A+ on this site's grading scale.
What time of day has the fewest delays on PDX to IAH?
The 5am–8am departure window is the strongest at 93.9% on time. The 8am–11am window is the weakest at 77.6%, 16 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 PDX to IAH?
July is the weakest month at 77.3% on time, compared with 92.7% 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
- IAH to PDX — the return legseparate record
- Portland International (PDX) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- United Airlines on PDX to IAH86.4%
- Alaska Airlines on PDX to IAH83.1%
- PDX to SEA, a related route84.8%
- ORD to IAH, a related route75.0%
- PDX to LAX, a related route87.4%
- United Airlines on-time record86.4%
- Alaska Airlines on-time record83.1%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. PDX to IAH and IAH to PDX are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.