Route reliability record

ORD→PDX

Chicago to Portland

Flights: 2,761
Period: July 2025 to June 2026
Distance: 1,739 mi
Carriers: 3

This route sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 2,761 flights, of which Alaska Airlines flew 506 at 72.8% on time.

Alaska Airlines is the most reliable of the three carriers covered here at 72.8% on time across 506 flights.

On time

69.5%

Arrivals under 15 minutes late, of 2,731 completed flights

Avg delay

63 min

Across delayed arrivals only, not all flights

Cancelled

0.87%

National rate is 1.81%

Best carrier

Alaska

72.8% on time across 506 flights

These figures cover 2,761 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 PDX

The choice of carrier is not cosmetic here. Alaska Airlines arrives on time 72.8% of the time; American Airlines manages 62.6%. Sample sizes sit next to every figure, because a two-point gap across 861 flights means less than a ten-point one.

On-time performance by carrier on ORD to PDX
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines	506	72.8%	50 min	1.19%	C
United Airlines	1,394	72.6%	61 min	0.43%	C+
American Airlines	861	62.6%	71 min	1.39%	D

Alaska leads American by 10 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 29 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am366 flights83.7%
8am–11am517 flights80.4%
11am–2pm422 flights71.5%
2pm–5pm716 flights68.0%
5pm–8pm97 flights54.7%
8pm–5am643 flights55.2%

Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 54.7% on time, against 83.7% 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 2pm–5pm window is the busiest, with 716 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 29 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.

Darker means more delays. Figures are on-time percentages.September best, December worst

December is the weak month at 56.4% on time, against 85.2% in September. 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. June was the busiest month here, with 321 flights.

Across the week, Tuesday is the strongest day at 73.2% on time and Sunday the weakest at 65.0%. 8 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 48% of the 53,000 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.

Late-arriving aircraft
48%
Carrier
28%
National Airspace System
19%
Extreme weather
5%
Security
0%

48% 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 53,000 reported delay minutes here, that single category outweighs weather by 10 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 52,652 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 83.7% on time here.

Cancellations are rare at 0.87%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

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.

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 77.5% on time across 2,766 flights, 8 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 8 points of difference.

The sample behind these figures is 2,761 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. September runs 85.2% on time and December 56.4%, a swing of 29 points. If the dates move at all, move them out of December before you think about anything else. 2,731 completed flights over 12 months sit behind that.

Common questions

ORD to PDX questions

How often is ORD to PDX delayed?

Roughly one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 30.5% of the 2,761 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on ORD to PDX?

Alaska Airlines leads at 72.8% on time across 506 flights. American Airlines is at the other end on 62.6%, a gap of 10 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 PDX?

The 5am–8am departure window is the strongest at 83.7% on time. The 5pm–8pm window is the weakest at 54.7%, 29 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 December delays on ORD to PDX?

December is the weakest month at 56.4% on time, compared with 85.2% in September. Across the year that is 29 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. ORD to PDX and PDX to ORD 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.

Key figures