Route reliability record
DEN→PDX
Denver to Portland
- Flights
- 4,289
- Period
- July 2025 to June 2026
- Distance
- 991 mi
- Carriers
- 5
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 roughly 55 minutes behind schedule. That rests on 4,289 flights, of which United Airlines flew 1,821 at 81.7% on time.
United Airlines is the most reliable of the three carriers covered here at 81.7% on time across 1,821 flights.
Key figures
On time
73.9%
Arrivals under 15 minutes late, of 4,267 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.44%
National rate is 1.81%
Best carrier
United
81.7% on time across 1,821 flights
These figures cover 4,289 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Which airline is most reliable on DEN to PDX
The choice of carrier is not cosmetic here. United Airlines arrives on time 81.7% of the time; Southwest Airlines manages 62.5%. Sample sizes sit next to every figure, because a two-point gap across 1,563 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,821 | 81.7% | 60 min | 0.44% | B+ |
| Frontier Airlinesthin sample | 311 | 80.3% | 69 min | 0.64% | B+ |
| Alaska Airlines | 581 | 77.5% | 55 min | 0.69% | B+ |
| Southwest Airlines | 1,563 | 62.5% | 47 min | 0.32% | D+ |
| SkyWest Airlinesthin sample | 13 | 46.2% | 42 min | 0.00% | F+ |
The spread between United and Southwest is 19 points, wide enough that it should decide the booking. On a hundred trips that is 19 more arrivals inside the on-time window.
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 30 points, against 19 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am218 flights87.1%
- 8am–11am816 flights85.3%
- 11am–2pm1,057 flights81.6%
- 2pm–5pm623 flights75.8%
- 5pm–8pm860 flights63.0%
- 8pm–5am715 flights57.0%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 57.0% on time, against 87.1% 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 1,057 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 25 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.
June is the worst month at 60.4% on time, 25 points below April, the best at 85.8%. 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. July was the busiest month here, with 461 flights.
Across the week, Tuesday is the strongest day at 78.4% on time and Monday the weakest at 70.7%. 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 53% of the 59,000 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.
- 53%Late-arriving aircraft
- 32%Carrier
- 13%National Airspace System
- 1%Extreme weather
- 0%Security
53% 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 59,000 reported delay minutes here, that single category outweighs weather by 40 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 58,754 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 87.1% on time here.
Cancellations are rare at 0.44%, 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
6.9% 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 roughly 55 minutes kind, which a normal layover absorbs.
The 991 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 80.8% on time across 4,290 flights, 7 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 7 points of difference.
The sample behind these figures is 4,289 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. April runs 85.8% on time and June 60.4%, a swing of 25 points. If the dates move at all, move them out of June before you think about anything else. 4,267 completed flights over 12 months sit behind that.
Common questions
DEN to PDX questions
How often is DEN to PDX delayed?
About 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 26.1% of the 4,289 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 55 minutes on average.
Which airline is most reliable on DEN to PDX?
United Airlines leads at 81.7% on time across 1,821 flights. Southwest Airlines is at the other end on 62.5%, a gap of 19 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 DEN to PDX?
The 5am–8am departure window is the strongest at 87.1% on time. The 8pm–5am window is the weakest at 57.0%, 30 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 June delays on DEN to PDX?
June is the weakest month at 60.4% on time, compared with 85.8% in April. Across the year that is 25 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
- PDX to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- Portland International (PDX) delay statistics
- United Airlines on-time record81.7%
- Frontier Airlines on-time record80.3%
- Alaska Airlines on-time record77.5%
- 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. DEN to PDX and PDX to DEN 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.