Carrier route record
DLSEA→DCA
Delta Air Lines · Seattle to Washington
- 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 SEA to DCA 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 15 points better than the national rate of 77.3%. When something does go wrong the average delay runs close to two hours. That rests on 364 flights, with a median arrival 11 minutes early.
Set against the rest of the country, Delta's SEA to DCA record is 15 points better than the US average of 77.3%. That gap is worth roughly 145 fewer late arrivals for every thousand flights.
Key figures
On time
91.8%
Arrivals under 15 minutes late, of 354 completed flights
Avg delay
119 min
Across delayed arrivals only, not all flights
Cancelled
2.75%
National rate is 1.89%
Whole route
82.6%
Every carrier on SEA to DCA, 1,092 flights
These figures cover 364 flights between September 2025 and August 2026. The median arrival is 11 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.
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Carrier by carrier
Delta against every carrier on SEA to DCA
Delta flew 364 of the 1,092 flights on SEA to DCA, about 33% of it. Its 91.8% on time is 9 points better than the route as a whole, which runs 82.6%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Delta at 91.8% to Alaska at 78.0%.
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page)thin sample | 364 | 91.8% | 119 min | 2.75% | A |
| Alaska Airlines | 728 | 78.0% | 54 min | 0.69% | B+ |
Flight by flight
Delta flight numbers on SEA to DCA
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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.
There are not enough flights in each departure window to split Delta's SEA to DCA record by time of day without the percentages moving on noise. The headline rate of 91.8% is the reliable figure here.
Across the year
Delta on SEA to DCA through the year
- Jul–Sep 202530 flights70.0%
- Oct–Dec 202592 flights91.1%
- Jan–Mar 202690 flights96.5%
- Apr–Jun 202691 flights95.6%
- Jul–Sep 202661 flights91.5%
Scale runs 60% to 100%.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 91.8% on time across 364 flights.
Delta on SEA to DCA did not run the same all year. Its best quarter was Jan–Mar 2026 at 96.5% on time and its weakest Jul–Sep 2025 at 70.0%, a swing of 27 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, Friday is the strongest day at 96.0% on time and Thursday the weakest at 78.8%, a spread of 17 points.
Arrival by arrival
How late Delta on SEA to DCA runs when it is late
Delta on SEA to DCA often beats the schedule: 146 of 354 completed flights, 41%, arrived 15 minutes or more early. The 29 late arrivals split 8 under half an hour, 10 between 30 and 60 minutes, and 11 an hour or more.
- 15+ min early146 flights41.2%
- Within 15 min179 flights50.6%
- 15–29 min late8 flights2.3%
- 30–59 min late10 flights2.8%
- 1–2 hours late5 flights1.4%
- 2+ hours late6 flights1.7%
Scale runs 0% to 100%.
Share of 354 completed flights by arrival against schedule.
5 of 25 late departures made up the time and arrived on time, 20% of them. 9 flights left on time and still arrived late.
The worst days
Worst days for Delta on SEA to DCA
The latest arrival of the period was on 13 November 2025, 16 hours 32 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 November 2025 | 16 hours 32 minutes | Carrier |
| 18 December 2025 | 7 hours 19 minutes | Carrier |
| 11 September 2025 | 6 hours 23 minutes | Carrier |
| 20 November 2025 | 4 hours 23 minutes | Carrier |
| 30 September 2025 | 3 hours | Carrier |
Delay causes
Why Delta runs late on this route
Carrier accounts for 85% of the 3,457 delay minutes carriers reported here, and the remaining four split what is left.
- 85%Carrier
- 9%National Airspace System
- 4%Late-arriving aircraft
- 2%Security
The largest share of delay minutes, 85%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,922 of the 3,457 delay minutes reported here. The split is drawn from 3,457 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
Badly late arrivals are rare here: only 3.1% land an hour or more behind schedule, against 8.3% 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 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 67.2% on time across 364 flights, 25 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 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 SEA to DCA
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 91.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 354 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to DCA, every carrier
- Delta on DCA to SEA, the return leg
- Alaska Airlines on SEA to DCA78.0%
- Delta Air Lines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- Ronald Reagan Washington National (DCA) delay statistics
- The US routes with the most cancellations
- What a cancellation rate actually tells you (and what it hides)
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.