Carrier route record

UAPWM→ORD

United Airlines · Portland to Chicago

Flights: 428
Period: July 2025 to June 2026
Share of route: 29%
Carriers: 4

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.

United on PWM to ORD lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 428 flights, with a median arrival 2 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate United on PWM to ORD from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

76.6%

Arrivals under 15 minutes late, of 418 completed flights

Avg delay

94 min

Across delayed arrivals only, not all flights

Cancelled

2.10%

National rate is 1.81%

Whole route

77.2%

Every carrier on PWM to ORD, 1,486 flights

These figures cover 428 flights between July 2025 and June 2026. Beyond the headline rate, 8.4% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

United against every carrier on PWM to ORD

United flew 428 of the 1,486 flights on PWM to ORD, about 29% of it. Its 76.6% on time is about level with the route as a whole at 77.2%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Republic at 82.3% to SkyWest at 65.2%. Two 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 PWM to ORD
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airways	558	82.3%	83 min	3.41%	B−
Envoy Airthin sample	200	82.2%	97 min	4.00%	B−
United Airlines (this page)	428	76.6%	94 min	2.10%	B
SkyWest Airlinesthin sample	300	65.2%	89 min	4.00%	C−

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 40 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–8am200 flights95.4%
8am–11am14 flights—
11am–2pm—
2pm–5pm25 flights—
5pm–8pm189 flights55.2%
8pm–5am—

Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 55.2% on time, against 95.4% 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 5am–8am window is the busiest, with 200 flights scheduled in it.

Across the year

United on PWM to ORD through the year

Jul–Sep 2025183 flights71.9%
Oct–Dec 202589 flights67.4%
Jan–Mar 20263 flights—
Apr–Jun 2026153 flights86.8%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 76.6% on time across 428 flights.

United on PWM to ORD did not run the same all year. Its best quarter was Apr–Jun 2026 at 86.8% on time and its weakest Oct–Dec 2025 at 67.4%, a swing of 19 points on roughly 143 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Friday is the strongest day at 80.0% on time and Thursday the weakest at 69.5%. 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. National Airspace System accounts for 51% of the 9,176 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.

National Airspace System
51%
Carrier
27%
Extreme weather
16%
Late-arriving aircraft
6%

Extreme weather accounts for 16% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.6 times the usual weather exposure. The split is drawn from 9,176 reported delay minutes.

51% 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 4,679 minutes out of 9,176, against a national NAS share of 21%.

Cancellations sit at 2.10% against a national 1.81%, which is ordinary. Diversions add another 0.23%.

Connections and stage length

What a delay here costs

8.4% 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 an hour and a half, which a normal layover absorbs.

The 900 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 71.0% on time across 429 flights, 6 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 6 points of difference.

One caution: this is a thin sample. 428 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 PWM to ORD

Put together: treat all of this as provisional. 428 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 76.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 418 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures