Carrier route record

DLDCA→SEA

Delta Air Lines · Washington to Seattle

Flights: 364
Period: September 2025 to August 2026
Share of route: 33%
Carriers: 2

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

Delta on DCA to SEA draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 364 flights, with a median arrival 2 minutes early.

The national on-time rate over the same period is 77.3%, so Delta on DCA to SEA runs 10 points behind the country as a whole. Across a thousand flights that is about 101 extra late arrivals.

On time

67.2%

Arrivals under 15 minutes late, of 354 completed flights

Avg delay

88 min

Across delayed arrivals only, not all flights

Cancelled

2.75%

National rate is 1.89%

Whole route

73.4%

Every carrier on DCA to SEA, 1,092 flights

These figures cover 364 flights between September 2025 and August 2026. Beyond the headline rate, 13.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Carrier by carrier

Delta against every carrier on DCA to SEA

Delta flew 364 of the 1,092 flights on DCA to SEA, about 33% of it. Its 67.2% on time is 6 points worse than the route as a whole, which runs 73.4%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from Alaska at 76.4% to Delta at 67.2%.

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	728	76.4%	50 min	0.69%	B+
Delta Air Lines (this page)thin sample	364	67.2%	88 min	2.75%	C

Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

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 364 flights.

5am–8am—
8am–11am—
11am–2pm—
2pm–5pm238 flights70.0%
5pm–8pm126 flights62.1%
8pm–5am—

Scale runs 55% to 75%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 2pm–5pm slot at 70.0% on time, ahead of 5pm–8pm at 62.1%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 2pm–5pm window is the busiest, with 238 flights scheduled in it.

Across the year

Delta on DCA to SEA through the year

Jul–Sep 202530 flights63.3%
Oct–Dec 202592 flights61.1%
Jan–Mar 202690 flights64.7%
Apr–Jun 202691 flights73.3%
Jul–Sep 202661 flights72.9%

Scale runs 55% to 80%.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 67.2% on time across 364 flights.

Delta on DCA to SEA did not run the same all year. Its best quarter was Apr–Jun 2026 at 73.3% on time and its weakest Oct–Dec 2025 at 61.1%, a swing of 12 points on roughly 73 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 82.0% on time and Thursday the weakest at 56.9%, a spread of 25 points.

Arrival by arrival

How late Delta on DCA to SEA runs when it is late

Delta on DCA to SEA often beats the schedule: 102 of 354 completed flights, 29%, arrived 15 minutes or more early. The 116 late arrivals split 39 under half an hour, 28 between 30 and 60 minutes, and 49 an hour or more.

15+ min early102 flights28.8%
Within 15 min136 flights38.4%
15–29 min late39 flights11.0%
30–59 min late28 flights7.9%
1–2 hours late26 flights7.3%
2+ hours late23 flights6.5%

Scale runs 0% to 100%.

Share of 354 completed flights by arrival against schedule.

12 of 81 late departures made up the time and arrived on time, 15% of them. In the other direction, 47 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SEA.

The worst days

Worst days for Delta on DCA to SEA

The latest arrival of the period was on 28 July 2026, 15 hours 26 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. On three of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).

The latest arrivals of Delta on DCA to SEA in the period
Date	Arrived late by	Largest filed cause
28 July 2026	15 hours 26 minutes	National Airspace System
1 April 2026	9 hours 19 minutes	Carrier
18 December 2025	7 hours 34 minutes	Late-arriving aircraft
11 June 2026	6 hours 54 minutes	Carrier
4 November 2025	5 hours 20 minutes	Carrier

Delay causes

Why Delta runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 10,000 reported delay minutes.

National Airspace System
34%
Carrier
30%
Late-arriving aircraft
30%
Extreme weather
7%

34% 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 3,429 minutes out of 10,000, against a national NAS share of 21%. The split is drawn from 10,191 reported delay minutes.

Cancellations run at 2.75%, against 1.89% nationally. That is roughly one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and stage length

What a delay here costs

13.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.

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 is a different operation and performs like one: it runs 91.8% on time across 364 flights, 25 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 25 points of difference.

One caution: this is a thin sample. 364 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 DCA to SEA

Put together: treat all of this as provisional. 364 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 67.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 354 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures