Carrier route record

ASDCA→SEA

Alaska Airlines · Washington to Seattle

Flights: 729
Period: July 2025 to June 2026
Share of route: 67%
Carriers: 2

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

Alaska on DCA to SEA lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about 55 minutes on average. That is a workable record, not a spotless one. That rests on 729 flights, with a median arrival 7 minutes early.

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

On time

76.7%

Arrivals under 15 minutes late, of 717 completed flights

Avg delay

54 min

Across delayed arrivals only, not all flights

Cancelled

1.10%

National rate is 1.81%

Whole route

73.2%

Every carrier on DCA to SEA, 1,094 flights

These figures cover 729 flights between July 2025 and June 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

Alaska against every carrier on DCA to SEA

Alaska flew 729 of the 1,094 flights on DCA to SEA, most of the route. Its 76.7% on time is 4 points better than the route as a whole, which runs 73.2%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Alaska at 76.7% to Delta at 66.1%.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on DCA to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines (this page)	729	76.7%	54 min	1.10%	B
Delta Air Lines	365	66.1%	92 min	3.01%	C−

Flight by flight

Alaska flight numbers on DCA to SEA

Departure window

When Alaska 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 729 flights.

5am–8am—
8am–11am365 flights80.0%
11am–2pm—
2pm–5pm—
5pm–8pm364 flights73.4%
8pm–5am—

Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.

The early departures do better, though not dramatically: 80.0% on time for the 8am–11am window against 73.4% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 8am–11am window is the busiest, with 365 flights scheduled in it.

Across the year

Alaska on DCA to SEA through the year

Darker means more delays. Figures are on-time percentages.September best, December worst

December is the weak month at 46.8% on time, against 93.3% in September. 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. January was the busiest month here, with 62 flights.

Across the week, Saturday is the strongest day at 86.3% on time and Sunday the weakest at 71.3%. 15 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Alaska runs late on this route

One category carries most of the weight here. National Airspace System accounts for 45% of the 9,062 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.

National Airspace System
45%
Late-arriving aircraft
26%
Carrier
18%
Extreme weather
10%

45% 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 4,112 minutes out of 9,062, against a national NAS share of 21%. The split is drawn from 9,062 reported delay minutes.

Cancellations sit at 1.10% against a national 1.81%, which is ordinary. Diversions add another 0.55%.

Connections and stage length

What a delay here costs

5.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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.

At 2,329 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.

The return leg runs 76.4% on time across 729 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 729 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 Alaska on DCA to SEA

Put together: treat all of this as provisional. 729 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 76.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 717 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