Carrier route record

DLSEA→PDX

Delta Air Lines · Seattle to Portland

Flights: 311
Period: July 2025 to June 2026
Share of route: 7%
Carriers: 3

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

Delta on SEA to PDX sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 311 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 3,343 at 86.1% on time.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on SEA to PDX from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

75.9%

Arrivals under 15 minutes late, of 311 completed flights

Avg delay

66 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

83.1%

Every carrier on SEA to PDX, 4,778 flights

These figures cover 311 flights between July 2025 and June 2026. The median arrival is 2 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 SEA to PDX

Delta flew 311 of the 4,778 flights on SEA to PDX, about 7% of it. Its 75.9% on time is 7 points worse than the route as a whole, which runs 83.1%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 86.1% to Delta at 75.9%.

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 Lines (this page)thin 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

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 311 flights.

The overnight block holds up unusually well at 74.4% on time across 281 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8pm–5am window is the busiest, with 281 flights scheduled in it.

Across the year

Delta on SEA to PDX through the year

Jul–Sep 202592 flights72.8%
Oct–Dec 202567 flights64.2%
Jan–Mar 202693 flights79.6%
Apr–Jun 202659 flights88.1%

Scale runs 55% to 95%. 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 75.9% on time across 311 flights.

Delta on SEA to PDX did not run the same all year. Its best quarter was Apr–Jun 2026 at 88.1% on time and its weakest Oct–Dec 2025 at 64.2%, a swing of 24 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, Wednesday is the strongest day at 81.4% on time and Thursday the weakest at 67.4%. 14 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 67% of the 4,980 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
67%
Late-arriving aircraft
25%
National Airspace System
6%
Extreme weather
2%

The largest share of delay minutes, 67%, 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 3,330 of the 4,980 delay minutes reported here. The split is drawn from 4,980 reported delay minutes.

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 4.5% 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 8pm–5am window matters as much as it does.

The return leg is a different operation and performs like one: it runs 87.8% on time across 312 flights, 12 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 12 points of difference.

One caution: this is a thin sample. 311 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 SEA to PDX

Put together: treat all of this as provisional. 311 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 75.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 311 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