Carrier route record

UAPHL→IAH

United Airlines · Philadelphia to Houston

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 PHL to IAH 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 77.3%. When something does go wrong the average delay runs an hour and a half. That rests on 954 flights, with a median arrival 14 minutes early.

Set against the rest of the country, United's PHL to IAH record is 8 points better than the US average of 77.3%. That gap is worth roughly 84 fewer late arrivals for every thousand flights.

On time

85.7%

Arrivals under 15 minutes late, of 942 completed flights

Avg delay

88 min

Across delayed arrivals only, not all flights

Cancelled

1.05%

National rate is 1.89%

Whole route

81.7%

Every carrier on PHL to IAH, 1,878 flights

These figures cover 954 flights between September 2025 and August 2026. The median arrival is 14 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 PHL to IAH

United flew 954 of the 1,878 flights on PHL to IAH, most of the route. Its 85.7% on time is 4 points better than the route as a whole, which runs 81.7%. Ranked by on-time rate it is first of five carriers on the route, where the range runs from United at 85.7% to Frontier at 67.6%. 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.

On-time performance by carrier on PHL to IAH
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines (this page)	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

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 32 points, against half a point between the best and worst carrier.

5am–8am123 flights94.3%
8am–11am218 flights90.7%
11am–2pm331 flights86.9%
2pm–5pm—
5pm–8pm188 flights83.4%
8pm–5am94 flights62.6%

Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 62.6% on time, against 94.3% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 11am–2pm window is the busiest, with 331 flights scheduled in it.

Across the year

United on PHL to IAH through the year

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

July is the worst month at 75.7% on time, 17 points below February, the best at 93.1%. 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. November was the busiest month here, with 89 flights.

Across the week, Friday is the strongest day at 87.9% on time and Sunday the weakest at 83.5%, a spread of 4 points.

Arrival by arrival

How late United on PHL to IAH runs when it is late

United on PHL to IAH often beats the schedule: 457 of 942 completed flights, 49%, arrived 15 minutes or more early. The 135 late arrivals split 42 under half an hour, 40 between 30 and 60 minutes, and 53 an hour or more.

15+ min early457 flights48.5%
Within 15 min350 flights37.2%
15–29 min late42 flights4.5%
30–59 min late40 flights4.2%
1–2 hours late28 flights3.0%
2+ hours late25 flights2.7%

Scale runs 0% to 100%.

Share of 942 completed flights by arrival against schedule.

A late pushback is often recovered here: of 140 departures that left 15 minutes late or more, 46 still arrived on time. 41 flights left on time and still arrived late.

The worst days

Worst days for United on PHL to IAH

The latest arrival of the period was on 20 May 2026, 18 hours 55 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across May, June, July, December and August, with no single month standing out.

The latest arrivals of United on PHL to IAH in the period
Date	Arrived late by	Largest filed cause
20 May 2026	18 hours 55 minutes	Carrier
14 June 2026	16 hours 2 minutes	National Airspace System
21 July 2026	8 hours 10 minutes	Extreme weather
26 December 2025	6 hours 15 minutes	Late-arriving aircraft
20 August 2026	5 hours 18 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.

National Airspace System
35%
Late-arriving aircraft
35%
Carrier
26%
Extreme weather
4%

35% 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 8 to one. The split is drawn from 11,850 reported delay minutes.

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 4,144 minutes out of 12,000, against a national NAS share of 21%.

Cancellations sit at 1.05% against a national 1.89%, which is ordinary. Diversions add another 0.21%.

Connections and stage length

What a delay here costs

5.6% 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 is a different operation and performs like one: it runs 81.5% on time across 954 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.

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 PHL to IAH

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 85.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 942 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures