Route reliability record

SEA→PDX

Seattle to Portland

Flights: 4,778
Period: July 2025 to June 2026
Distance: 129 mi
Carriers: 3

This route lands a B+, 6 points better than the national rate of 77.6%. About one flight in six arrive 15 minutes late or worse, and those flights are late by about 50 minutes on average. That is a workable record, not a spotless one. That rests on 4,778 flights, of which SkyWest Airlines flew 3,343 at 86.1% on time.

Set against the rest of the country, this route's record is 6 points better than the US average of 77.6%. That gap is worth roughly 55 fewer late arrivals for every thousand flights.

On time

83.1%

Arrivals under 15 minutes late, of 4,746 completed flights

Avg delay

51 min

Across delayed arrivals only, not all flights

Cancelled

0.67%

National rate is 1.81%

Best carrier

SkyWest

86.1% on time across 3,343 flights

These figures cover 4,778 flights between July 2025 and June 2026. The median arrival is 6 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 SEA to PDX

The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 86.1% of the time; Alaska Airlines manages 76.3%. Sample sizes sit next to every figure, because a two-point gap across 1,124 flights means less than a ten-point one.

On-time performance by carrier on SEA to PDX
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	3,343	86.1%	53 min	0.51%	A+
Alaska Airlines	1,124	76.3%	41 min	1.33%	B
Delta Air Linesthin sample	311	75.9%	66 min	0.00%	B+

SkyWest leads Alaska 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 15 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am568 flights93.6%
8am–11am640 flights88.6%
11am–2pm963 flights82.5%
2pm–5pm677 flights80.6%
5pm–8pm694 flights81.3%
8pm–5am1,236 flights78.4%

Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 93.6% of the time, against 78.4% for the overnight window. That is 15 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 1,236 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 17 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.April best, December worst

December is the weak month at 73.7% on time, against 90.6% in April. 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. September was the busiest month here, with 433 flights.

Across the week, Tuesday is the strongest day at 85.1% on time and Thursday the weakest at 79.4%. 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 51% of the 40,000 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.

Carrier
51%
Late-arriving aircraft
25%
Extreme weather
13%
National Airspace System
12%
Security
0%

Extreme weather accounts for 13% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.0 times the usual weather exposure. The split is drawn from 40,415 reported delay minutes.

The largest share of delay minutes, 51%, 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 20,000 of the 40,000 delay minutes reported here.

Cancellations are rare at 0.67%, 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

Badly late arrivals are rare here: only 3.8% land an hour or more behind schedule, against 8.1% 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 84.8% on time across 4,938 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 4,778 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 90.6% on time and December 73.7%, a swing of 17 points. If the dates move at all, move them out of December before you think about anything else. 4,746 completed flights over 12 months sit behind that.

Common questions

SEA to PDX questions

How often is SEA to PDX 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 16.9% of the 4,778 flights in this analysis, against 22.4% nationally. Delayed flights are late by about 50 minutes on average.

Which airline is most reliable on SEA to PDX?

SkyWest Airlines leads at 86.1% on time across 3,343 flights. Alaska Airlines is at the other end on 76.3%, 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 SEA to PDX?

The 5am–8am departure window is the strongest at 93.6% on time. The 8pm–5am window is the weakest at 78.4%, 15 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 SEA to PDX?

December is the weakest month at 73.7% on time, compared with 90.6% in April. Across the year that is 17 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. SEA to PDX and PDX to SEA 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