Route reliability record
PDX→SEA
Portland to Seattle
- Flights
- 4,937
- Period
- June 2025 to May 2026
- Distance
- 129 mi
- Carriers
- 3
This route earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.4%. When something does go wrong the average delay runs about 55 minutes. That rests on 4,937 flights, of which SkyWest Airlines flew 3,492 at 84.2% on time.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.4%. That gap is worth roughly 67 fewer late arrivals for every thousand flights.
Key figures
On time
84.1%
Arrivals under 15 minutes late, of 4,904 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.67%
National rate is 1.80%
Best carrier
SkyWest
84.2% on time across 3,492 flights
These figures cover 4,937 flights between June 2025 and May 2026. The median arrival is 7 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 SEA
The two carriers here are closely matched: 2 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 |
|---|---|---|---|---|---|
| Delta Air Linesthin sample | 342 | 88.6% | 60 min | 0.00% | A+ |
| SkyWest Airlines | 3,492 | 84.2% | 57 min | 0.54% | B+ |
| Alaska Airlines | 1,103 | 82.3% | 45 min | 1.27% | B |
No carrier stands out. SkyWest tops the table at 84.2%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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 11 points, against 2 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,231 flights90.4%
- 8am–11am905 flights81.0%
- 11am–2pm836 flights83.8%
- 2pm–5pm809 flights84.2%
- 5pm–8pm826 flights79.2%
- 8pm–5am330 flights81.7%
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.4% of the time, against 79.2% for the evening window. That is 11 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.
Across the year
When delays peak on this route
This route's year swings by 16 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 75.4% on time, 16 points below February, the best at 91.2%. 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.
Across the week, Saturday is the strongest day at 86.9% on time and Thursday the weakest at 80.5%. 6 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. Carrier accounts for 42% of the 43,000 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.
- 42%Carrier
- 27%Late-arriving aircraft
- 19%National Airspace System
- 10%Extreme weather
- 0%Security
The largest share of delay minutes, 42%, 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 18,000 of the 43,000 delay minutes reported here.
Cancellations are rare at 0.67%, below the national 1.80% 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
Badly late arrivals are rare here: only 3.9% land an hour or more behind schedule, against 8.2% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 129 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg runs 82.4% on time across 4,748 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 4,937 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 91.2% on time and June 75.4%, a swing of 16 points. If the dates move at all, move them out of June before you think about anything else.
Common questions
PDX to SEA questions
How often is PDX to SEA delayed?
About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.9% of the 4,937 flights in this analysis, against 22.6% nationally. Delayed flights are late by about 55 minutes on average.
Which airline is most reliable on PDX to SEA?
SkyWest Airlines leads at 84.2% on time across 3,492 flights. Alaska Airlines is at the other end on 82.3%, a gap of 2 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 SEA?
The 5am–8am departure window is the strongest at 90.4% on time. The 5pm–8pm window is the weakest at 79.2%, 11 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 PDX to SEA?
June is the weakest month at 75.4% on time, compared with 91.2% in February. Across the year that is 16 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
- SEA to PDX — the return legseparate record
- Portland International (PDX) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on-time record88.6%
- SkyWest Airlines on-time record84.2%
- Alaska Airlines on-time record82.3%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. PDX to SEA and SEA 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, June 2025 to May 2026. Updated monthly. How this data is collected.