Carrier route record

DLPDX→SEA

Delta Air Lines · Portland to Seattle

Flights: 312
Period: July 2025 to June 2026
Share of route: 6%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on PDX to SEA earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 10 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 312 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 3,501 at 85.2% on time.

Set against the rest of the country, Delta's PDX to SEA record is 10 points better than the US average of 77.6%. That gap is worth roughly 102 fewer late arrivals for every thousand flights.

On time

87.8%

Arrivals under 15 minutes late, of 312 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

84.8%

Every carrier on PDX to SEA, 4,938 flights

These figures cover 312 flights between July 2025 and June 2026. The median arrival is 12 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

Delta against every carrier on PDX to SEA

Delta flew 312 of the 4,938 flights on PDX to SEA, about 6% of it. Its 87.8% on time is 3 points better than the route as a whole, which runs 84.8%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 87.8% to Alaska at 82.6%.

The two carriers here are closely matched: 3 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.

On-time performance by carrier on PDX to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)thin sample	312	87.8%	61 min	0.00%	A+
SkyWest Airlines	3,501	85.2%	59 min	0.54%	A+
Alaska Airlines	1,125	82.6%	42 min	1.16%	B

No carrier stands out. SkyWest tops the table at 85.2%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.

Departure window

When Delta runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 312 flights.

There are not enough flights in each departure window to split Delta's PDX to SEA record by time of day without the percentages moving on noise. The headline rate of 87.8% is the reliable figure here.

Across the year

Delta on PDX to SEA through the year

Jul–Sep 202592 flights82.6%
Oct–Dec 202568 flights94.1%
Jan–Mar 202692 flights94.6%
Apr–Jun 202660 flights78.3%

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

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 87.8% on time across 312 flights.

Delta on PDX to SEA did not run the same all year. Its best quarter was Jan–Mar 2026 at 94.6% on time and its weakest Apr–Jun 2026 at 78.3%, a swing of 16 points on roughly 78 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Saturday is the strongest day at 93.2% on time and Wednesday the weakest at 82.6%. 11 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 48% of the 2,328 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
48%
National Airspace System
32%
Late-arriving aircraft
20%

32% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 756 minutes out of 2,328, against a national NAS share of 21%. The split is drawn from 2,328 reported delay minutes.

The largest share of delay minutes, 48%, 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 1,107 of the 2,328 delay minutes reported here.

Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 2.2% 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 is a different operation and performs like one: it runs 75.9% on time across 311 flights, 12 points below 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 12 points of difference.

One caution: this is a thin sample. 312 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Delta on PDX to SEA

Put together: treat all of this as provisional. 312 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 87.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 312 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures