Route reliability record
ORD→PWM
Chicago to Portland
- Flights
- 1,486
- Period
- July 2025 to June 2026
- Distance
- 900 mi
- Carriers
- 4
This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 1,486 ORD to PWM flights, of which Republic Airways flew 558 at 75.8% on time.
Best time to fly ORD to PWM: a 8am–11am departure, ideally on a Friday. Flights in that window arrived on time 85.4% of the time and Friday flights 77.9%, against 74.0% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
74.0%
Arrivals under 15 minutes late, of 1,448 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
2.49%
National rate is 1.81%
Best carrier
Republic
75.8% on time across 558 flights
These figures cover 1,486 flights between July 2025 and June 2026. Beyond the headline rate, 9.5% 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
Which airline is most reliable on ORD to PWM
The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 199 | 82.3% | 72 min | 3.52% | B− |
| Republic Airways | 558 | 75.8% | 69 min | 2.87% | B |
| United Airlines | 429 | 71.0% | 70 min | 1.17% | C |
| SkyWest Airlinesthin sample | 300 | 69.4% | 68 min | 3.00% | C |
No carrier stands out. Republic tops the table at 75.8%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Best ways to make this trip
The most reliable ways to fly Chicago to Portland
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. ORD → PWMChicago to Portland | Republic Airways | 73.6% | 75.8% | 2.87% | 8am–11am, Tue | — |
| 2. ORD → PWMChicago to Portland | United Airlines | 70.2% | 71.0% | 1.17% | 11am–2pm, Mon | — |
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 25 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am26 flights—
- 8am–11am241 flights85.4%
- 11am–2pm433 flights75.4%
- 2pm–5pm222 flights83.2%
- 5pm–8pm448 flights60.2%
- 8pm–5am116 flights75.0%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 60.2% on time, against 85.4% for the 8am–11am 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 5pm–8pm window is the busiest, with 448 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 26 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.
January is the weak month at 60.6% on time, against 86.2% in February. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. August was the busiest month here, with 177 flights.
Across the week, Friday is the strongest day at 77.9% on time and Saturday the weakest at 71.0%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 44% of the 26,000 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.
- 44%Late-arriving aircraft
- 31%Carrier
- 17%National Airspace System
- 7%Extreme weather
44% 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 26,000 reported delay minutes here, that single category outweighs weather by 6 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 26,207 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 85.4% on time here.
Cancellations sit at 2.49% against a national 1.81%, which is ordinary. Diversions add another 0.07%.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.5% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
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 77.2% on time across 1,486 flights, 3 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 3 points of difference.
The sample behind these figures is 1,486 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 PWM 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 86.2% on time and January 60.6%, a swing of 26 points. If the dates move at all, move them out of January before you think about anything else. 1,448 completed flights over 12 months sit behind that.
Common questions
ORD to PWM questions
How often is ORD to PWM delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 26.0% of the 1,486 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on ORD to PWM?
Republic Airways leads at 75.8% on time across 558 flights. United Airlines is at the other end on 71.0%, a gap of 5 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 ORD to PWM?
The 8am–11am departure window is the strongest at 85.4% on time. The 5pm–8pm window is the weakest at 60.2%, 25 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 January delays on ORD to PWM?
January is the weakest month at 60.6% on time, compared with 86.2% in February. Across the year that is 26 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
- PWM to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Envoy Air on ORD to PWM82.3%
- Republic Airways on ORD to PWM75.8%
- United Airlines on ORD to PWM71.0%
- SkyWest Airlines on ORD to PWM69.4%
- ORD to LGA, a related route67.3%
- BWI to PWM, a related route79.2%
- ORD to BOS, a related route67.6%
- Envoy Air on-time record82.3%
- Republic Airways on-time record75.8%
- United Airlines on-time record71.0%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. ORD to PWM and PWM to ORD 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.