Route reliability record
PDX→ORD
Portland to Chicago
- Flights
- 2,766
- Period
- July 2025 to June 2026
- Distance
- 1,739 mi
- Carriers
- 3
This route lands a B, level with the national rate of 77.6%. Roughly one flight in four arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 2,766 flights, of which United Airlines flew 1,393 at 80.7% on time.
United Airlines is the most reliable of the three carriers covered here at 80.7% on time across 1,393 flights.
Key figures
On time
77.5%
Arrivals under 15 minutes late, of 2,717 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
1.05%
National rate is 1.81%
Best carrier
United
80.7% on time across 1,393 flights
These figures cover 2,766 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
Which airline is most reliable on PDX to ORD
The choice of carrier is not cosmetic here. United Airlines arrives on time 80.7% of the time; American Airlines manages 74.0%. Sample sizes sit next to every figure, because a two-point gap across 863 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,393 | 80.7% | 68 min | 0.65% | B+ |
| Alaska Airlines | 510 | 74.5% | 39 min | 1.37% | C |
| American Airlines | 863 | 74.0% | 95 min | 1.51% | C |
United leads American by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 20 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am863 flights81.1%
- 8am–11am330 flights78.2%
- 11am–2pm541 flights72.4%
- 2pm–5pm258 flights63.0%
- 5pm–8pm55 flights69.1%
- 8pm–5am719 flights82.5%
Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.
The overnight block holds up unusually well at 82.5% on time across 719 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 5am–8am window is the busiest, with 863 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 27 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.
July is the worst month at 62.6% on time, 27 points below February, the best at 89.8%. 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. June was the busiest month here, with 322 flights.
Across the week, Saturday is the strongest day at 79.6% on time and Sunday the weakest at 73.1%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 44,000 reported delay minutes.
- 37%Carrier
- 34%National Airspace System
- 27%Late-arriving aircraft
- 1%Extreme weather
34% 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 15,000 minutes out of 44,000, against a national NAS share of 21%. The split is drawn from 43,955 reported delay minutes.
The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 16,000 of the 44,000 delay minutes reported here.
Cancellations sit at 1.05% against a national 1.81%, which is ordinary. Diversions add another 0.72%.
Connections and stage length
What a delay here actually costs
6.5% 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 are the a little over an hour kind, which a normal layover absorbs.
At 1,739 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 69.5% on time across 2,761 flights, 8 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 8 points of difference.
The sample behind these figures is 2,766 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.
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 89.8% on time and July 62.6%, a swing of 27 points. If the dates move at all, move them out of July before you think about anything else. 2,717 completed flights over 12 months sit behind that.
Common questions
PDX to ORD questions
How often is PDX to ORD delayed?
Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.5% of the 2,766 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 PDX to ORD?
United Airlines leads at 80.7% on time across 1,393 flights. American Airlines is at the other end on 74.0%, a gap of 7 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 PDX to ORD?
The 8pm–5am departure window is the strongest at 82.5% on time. The 2pm–5pm window is the weakest at 63.0%, 20 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 July delays on PDX to ORD?
July is the weakest month at 62.6% on time, compared with 89.8% in February. Across the year that is 27 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
- ORD to PDX — the return legseparate record
- Portland International (PDX) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- United Airlines on-time record80.7%
- Alaska Airlines on-time record74.5%
- American Airlines on-time record74.0%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. PDX to ORD and ORD to PDX are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.