Carrier route record
UAIAH→PHL
United Airlines · Houston to Philadelphia
- Flights
- 891
- Period
- July 2025 to June 2026
- Share of route
- 49%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to PHL lands a B, 5 points better than the national rate of 77.6%. About one flight in six arrives 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 891 flights, with a median arrival 5 minutes early.
Set against the rest of the country, United's IAH to PHL record is 5 points better than the US average of 77.6%. That gap is worth roughly 54 fewer late arrivals for every thousand flights.
Key figures
On time
83.0%
Arrivals under 15 minutes late, of 882 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
1.01%
National rate is 1.81%
Whole route
79.7%
Every carrier on IAH to PHL, 1,832 flights
These figures cover 891 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
United against every carrier on IAH to PHL
United flew 891 of the 1,832 flights on IAH to PHL, about 49% of it. Its 83.0% on time is 3 points better than the route as a whole, which runs 79.7%. Ranked by on-time rate it is first of six carriers on the route, where the range runs from United at 83.0% to Republic at 60.0%. Four of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 (this page) | 891 | 83.0% | 67 min | 1.01% | B |
| American Airlines | 717 | 78.2% | 159 min | 3.35% | B− |
| Spirit Airlinesthin sample | 42 | 76.9% | 151 min | 4.76% | B− |
| Frontier Airlinesthin sample | 70 | 72.5% | 80 min | 1.43% | C |
| PSA Airlinesthin sample | 92 | 70.8% | 162 min | 2.17% | C |
| Republic Airwaysthin sample | 20 | 60.0% | 150 min | 0.00% | D+ |
Flight by flight
United flight numbers on IAH to PHL
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 18 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–8am310 flights92.2%
- 8am–11am—
- 11am–2pm176 flights85.1%
- 2pm–5pm66 flights73.8%
- 5pm–8pm339 flights75.2%
- 8pm–5am—
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 92.2% of the time, against 73.8% for the afternoon 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. The 5pm–8pm window is the busiest, with 339 flights scheduled in it.
Across the year
United on IAH to PHL through the year
July is the worst month at 65.1% on time, 25 points below December, the best at 89.9%. 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. November was the busiest month here, with 89 flights.
Across the week, Tuesday is the strongest day at 89.6% on time and Sunday the weakest at 78.3%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 45% of the 10,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 45%Late-arriving aircraft
- 26%National Airspace System
- 24%Carrier
- 5%Extreme weather
45% 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 10,000 reported delay minutes here, that single category outweighs weather by 9 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 10,091 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 92.2% on time here.
Cancellations sit at 1.01% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
6.2% 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 last about an hour, 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. 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 is a different operation and performs like one: it runs 86.9% on time across 891 flights, 4 points above 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.
One caution: this is a thin sample. 891 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 United on IAH to PHL
Put together: treat all of this as provisional. 891 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 83.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 882 completed flights over 12 months sit behind that.
Related
Where to go next
- IAH to PHL, every carrier
- United on PHL to IAH, the return leg
- American Airlines on IAH to PHL78.2%
- United Airlines network-wide record
- George Bush Intercontinental (IAH) delay statistics
- Philadelphia International (PHL) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.