Route reliability record
DEN→PDX
Denver to Portland
- Flights
- 4,280
- Period
- September 2025 to August 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, 3 points worse than the national rate of 77.3%. The late ones land about 55 minutes behind schedule. That rests on 4,280 DEN to PDX flights, of which United Airlines flew 1,822 at 82.3% on time.
Best time to fly DEN to PDX: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 85.6% of the time and Tuesday flights 79.2%, against 74.8% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 82.3% on time across 1,822 flights.
Key figures
On time
74.8%
Arrivals under 15 minutes late, of 4,265 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.33%
National rate is 1.89%
Best carrier
United
82.3% on time across 1,822 flights
These figures cover 4,280 flights between September 2025 and August 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.
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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 82.3% of the time; Southwest Airlines manages 62.1%. Sample sizes sit next to every figure, because a two-point gap across 1,547 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Frontier Airlinesthin sample | 255 | 85.4% | 60 min | 0.39% | A+ |
| United Airlines | 1,822 | 82.3% | 59 min | 0.38% | B+ |
| Alaska Airlines | 643 | 80.5% | 60 min | 0.31% | B+ |
| Southwest Airlines | 1,547 | 62.1% | 51 min | 0.26% | D+ |
| SkyWest Airlinesthin sample | 13 | 46.2% | 42 min | 0.00% | F+ |
The spread between United and Southwest is 20 points, wide enough that it should decide the booking. On a hundred trips that is 20 more arrivals inside the on-time window.
Flight by flight
Flights on DEN to PDX
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Denver 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. DEN → PDXDenver to Portland | United Airlines | 82.0% | 82.3% | 0.38% | 8am–11am, Sun | UA 1247 07:50 |
| 2. DEN → PDXDenver to Portland | Alaska Airlines | 80.3% | 80.5% | 0.31% | 8am–11am, Sat | — |
| 3. DEN → PDXDenver to Portland | Southwest Airlines | 61.9% | 62.1% | 0.26% | 8am–11am, Tue | — |
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 28 points, against 20 points between the best and worst carrier.
- 5am–8am171 flights83.6%
- 8am–11am832 flights85.6%
- 11am–2pm1,101 flights83.1%
- 2pm–5pm669 flights77.1%
- 5pm–8pm874 flights63.0%
- 8pm–5am633 flights57.7%
Scale runs 50% to 90%.
The 8pm–5am window is where this operation falls apart: 57.7% on time, against 85.6% 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 11am–2pm window is the busiest, with 1,101 flights scheduled in it.
Explore
Filter DEN to PDX by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On DEN to PDX, the best departure window is 8am–11am at 85.6% on time and the worst is 8pm–5am at 57.7%, a wide gap of 27.9 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am83.6%
- 8–11am85.6%
- 11am–2pm83.1%
- 2–5pm77.1%
- 5–8pm63.0%
- 8pm–5am57.7%
best all US flightsScale 50% to 95%.
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 457 flights.
Across the week, Tuesday is the strongest day at 79.2% on time and Monday the weakest at 71.3%, a spread of 8 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 54% of the 59,000 delay minutes carriers reported here, and the remaining four split what is left.
- 54%Late-arriving aircraft
- 31%Carrier
- 13%National Airspace System
- 2%Extreme weather
- 0%Security
54% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 59,000 reported delay minutes here, that single category outweighs weather by 36 to one. The split is drawn from 58,544 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 85.6% on time here.
Cancellations are rare at 0.33%, below the national 1.89% 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
7.0% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 55 minutes, 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.
The return leg is a different operation and performs like one: it runs 82.3% on time across 4,280 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 4,280 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 PDX 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. 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. 4,265 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 arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 25.2% of the 4,280 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 55 minutes on average.
Which airline is most reliable on DEN to PDX?
United Airlines leads at 82.3% on time across 1,822 flights. Southwest Airlines is at the other end on 62.1%, a gap of 20 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 8am–11am departure window is the strongest at 85.6% on time. The 8pm–5am window is the weakest at 57.7%, 28 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
- Frontier Airlines on DEN to PDX85.4%
- United Airlines on DEN to PDX82.3%
- Alaska Airlines on DEN to PDX80.5%
- Southwest Airlines on DEN to PDX62.1%
- DEN to PHX, a related route75.6%
- SEA to PDX, a related route82.2%
- DEN to SLC, a related route78.2%
- Frontier Airlines on-time record85.4%
- United Airlines on-time record82.3%
- Alaska Airlines on-time record80.5%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.