Carrier route record
UAIAH→PHL
United Airlines · Houston to Philadelphia
- Flights
- 954
- Period
- September 2025 to August 2026
- Share of route
- 51%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to PHL 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 a little over an hour on average. That rests on 954 flights, with a median arrival 5 minutes early.
Set against the rest of the country, United's IAH to PHL record is 4 points better than the US average of 77.3%. That gap is worth roughly 42 fewer late arrivals for every thousand flights.
Key figures
On time
81.5%
Arrivals under 15 minutes late, of 944 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
0.94%
National rate is 1.89%
Whole route
78.8%
Every carrier on IAH to PHL, 1,878 flights
These figures cover 954 flights between September 2025 and August 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.
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Carrier by carrier
United against every carrier on IAH to PHL
United flew 954 of the 1,878 flights on IAH to PHL, most of the route. Its 81.5% on time is 3 points better than the route as a whole, which runs 78.8%. Ranked by on-time rate it is first of five carriers on the route, where the range runs from United at 81.5% to Republic at 63.9%. Three 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) | 954 | 81.5% | 69 min | 0.94% | B+ |
| American Airlines | 724 | 77.6% | 97 min | 3.18% | B− |
| Frontier Airlinesthin sample | 72 | 71.8% | 85 min | 1.39% | C |
| PSA Airlinesthin sample | 92 | 70.8% | 162 min | 2.17% | C |
| Republic Airwaysthin sample | 36 | 63.9% | 147 min | 0.00% | D+ |
Flight by flight
United flight numbers on IAH to PHL
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 29 points, against half a point between the best and worst carrier.
- 5am–8am331 flights92.1%
- 8am–11am—
- 11am–2pm194 flights84.9%
- 2pm–5pm94 flights63.0%
- 5pm–8pm335 flights74.0%
- 8pm–5am—
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 92.1% of the time, against 63.0% for the afternoon window. That is 29 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 335 flights scheduled in it.
Across the year
United on IAH to PHL through the year
July is the worst month at 53.4% on time, 37 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, Saturday is the strongest day at 86.8% on time and Thursday the weakest at 77.6%, a spread of 9 points.
Arrival by arrival
How late United on IAH to PHL runs when it is late
The 175 late arrivals split 53 under half an hour, 53 between 30 and 60 minutes, and 69 an hour or more.
- 15+ min early215 flights22.8%
- Within 15 min554 flights58.7%
- 15–29 min late53 flights5.6%
- 30–59 min late53 flights5.6%
- 1–2 hours late40 flights4.2%
- 2+ hours late29 flights3.1%
Scale runs 0% to 100%.
Share of 944 completed flights by arrival against schedule.
22 of 164 late departures made up the time and arrived on time, 13% of them. 33 flights left on time and still arrived late.
The worst days
Worst days for United on IAH to PHL
The latest arrival of the period was on 7 March 2026, 5 hours 7 minutes behind schedule; most of its delay minutes were filed as extreme weather. The five worst days are spread across March, July and June, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 March 2026 | 5 hours 7 minutes | Extreme weather |
| 2 July 2026 | 5 hours 2 minutes | Carrier |
| 28 July 2026 | 4 hours 37 minutes | National Airspace System |
| 11 March 2026 | 4 hours 30 minutes | Late-arriving aircraft |
| 2 June 2026 | 3 hours 39 minutes | Late-arriving aircraft |
Delay causes
Why United runs late on this route
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.
- 38%Late-arriving aircraft
- 38%National Airspace System
- 22%Carrier
- 3%Extreme weather
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 12,000 reported delay minutes here, that single category outweighs weather by 13 to one. The split is drawn from 12,051 reported delay minutes.
38% 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 4,520 minutes out of 12,000, against a national NAS share of 21%.
Cancellations sit at 0.94% against a national 1.89%, which is ordinary. Diversions add another 0.10%.
Connections and stage length
What a delay here costs
7.3% 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 a little over 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.
The return leg is a different operation and performs like one: it runs 85.7% on time across 954 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. 954 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. 954 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 81.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 944 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 PHL77.6%
- 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 7.05 million flight records
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.