Route reliability record
PHL→IAH
Philadelphia to Houston
- Flights
- 1,878
- Period
- September 2025 to August 2026
- Distance
- 1,325 mi
- Carriers
- 5
This route lands a B, 4 points better than the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 1,878 PHL to IAH flights, of which United Airlines flew 954 at 85.7% on time.
Best time to fly PHL to IAH: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 87.9% of the time and Wednesday flights 86.3%, against 81.7% for the route overall.
Set against the rest of the country, this route's record is 4 points better than the US average of 77.3%. That gap is worth roughly 44 fewer late arrivals for every thousand flights.
Key figures
On time
81.7%
Arrivals under 15 minutes late, of 1,837 completed flights
Avg delay
86 min
Across delayed arrivals only, not all flights
Cancelled
1.92%
National rate is 1.89%
Best carrier
United
85.7% on time across 954 flights
These figures cover 1,878 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on PHL to IAH
The choice of carrier is not cosmetic here. United Airlines arrives on time 85.7% of the time; American Airlines manages 78.1%. Sample sizes sit next to every figure, because a two-point gap across 724 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 954 | 85.7% | 88 min | 1.05% | A |
| Republic Airwaysthin sample | 36 | 83.3% | 140 min | 0.00% | B+ |
| American Airlines | 724 | 78.1% | 86 min | 3.18% | B− |
| PSA Airlinesthin sample | 92 | 77.3% | 77 min | 2.17% | B |
| Frontier Airlinesthin sample | 72 | 67.6% | 64 min | 1.39% | C |
American Airlines cancels 3.2% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
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Best ways to make this trip
The most reliable ways to fly Philadelphia to Houston
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. PHL → IAHPhiladelphia to Houston | United Airlines | 84.8% | 85.7% | 1.05% | 5am–8am, Fri | — |
| 2. PHL → IAHPhiladelphia to Houston | American Airlines | 75.6% | 78.1% | 3.18% | 8am–11am, Wed | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 23 points, against 8 points between the best and worst carrier.
- 5am–8am166 flights87.9%
- 8am–11am595 flights86.8%
- 11am–2pm452 flights83.1%
- 2pm–5pm21 flights—
- 5pm–8pm433 flights80.1%
- 8pm–5am211 flights65.2%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 87.9% of the time, against 65.2% for the overnight window. That is 23 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 595 flights scheduled in it.
Explore
Filter PHL to IAH by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On PHL to IAH, the best departure window is 5am–8am at 87.9% on time and the worst is 8pm–5am at 65.2%, a wide gap of 22.7 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am87.9%
- 8–11am86.8%
- 11am–2pm83.1%
- 2–5pm—
- 5–8pm80.1%
- 8pm–5am65.2%
best all US flightsScale 55% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 18 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 74.0% on time, 18 points below February, the best at 91.8%. 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. June was the busiest month here, with 187 flights.
Across the week, Wednesday is the strongest day at 86.3% on time and Sunday the weakest at 77.1%, a spread of 9 points.
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 29,000 reported delay minutes.
- 39%Late-arriving aircraft
- 27%Carrier
- 27%National Airspace System
- 6%Extreme weather
39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 29,000 reported delay minutes here, that single category outweighs weather by 6 to one. The split is drawn from 28,837 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 87.9% on time here.
Cancellations sit at 1.92% against a national 1.89%, which is ordinary. Diversions add another 0.27%.
Connections and stage length
What a delay here actually costs
7.6% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.
The 1,325 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 78.8% on time across 1,878 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 1,878 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. February runs 91.8% on time and June 74.0%, a swing of 18 points. If the dates move at all, move them out of June before you think about anything else. 1,837 completed flights over 12 months sit behind that.
Common questions
PHL to IAH questions
How often is PHL to IAH delayed?
Roughly one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.3% of the 1,878 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on PHL to IAH?
United Airlines leads at 85.7% on time across 954 flights. American Airlines is at the other end on 78.1%, a gap of 8 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 PHL to IAH?
The 5am–8am departure window is the strongest at 87.9% on time. The 8pm–5am window is the weakest at 65.2%, 23 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 PHL to IAH?
June is the weakest month at 74.0% on time, compared with 91.8% in February. Across the year that is 18 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 PHL — the return legseparate record
- Philadelphia International (PHL) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- United Airlines on PHL to IAH85.7%
- American Airlines on PHL to IAH78.1%
- PHL to ATL, a related route78.0%
- ORD to IAH, a related route76.0%
- PHL to MCO, a related route72.4%
- United Airlines on-time record85.7%
- Republic Airways on-time record83.3%
- American Airlines on-time record78.1%
- 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. PHL to IAH and IAH to PHL 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.