Dulles (IAD) to Seattle (SEA) flights
Alaska Airlines, United Airlines, Delta Air Lines fly nonstop from Washington Dulles International Airport to Seattle-Tacoma International Airport, with about 47 flights a week in July 2026. The 2,305-mile flight takes about 5h 46m gate to gate.
- Distance
- 2,305 mi · 3,710 km
- Flight time
- 5h 46m
- Airlines
- 3
- Seats filled
- 86%
Airlines flying IAD to SEA
| Airline | Flights a week | Aircraft | Passengers (12 months) | Flight time |
|---|---|---|---|---|
| Alaska Airlines | 20 | Boeing 737-900ER, Boeing 737 MAX 9, Boeing 737-800 | 124,914 | 5h 45m |
| United Airlines | 20 | Boeing 737 MAX 9, Boeing 737 MAX 8, Boeing 737-900ER | 100,873 | 5h 47m |
| Delta Air Lines | 7 | Airbus A220-300, Airbus A220-100 | 36,720 | 5h 49m |
Airlines are the operating carrier: regional airlines such as SkyWest or Horizon often fly under a larger airline's brand.
IAD to SEA flight schedule
11 flight numbers flew this route in August 2026, 3 of them almost daily. The first usually leaves at 6:03am and the last at 6:14pm. Times are local and can change; check with the airline before you book.
| Flight | Departs | Arrives | Days flown in August 2026 | On time (12 months) |
|---|---|---|---|---|
| AS 409Alaska Airlines | 6:03am | 8:48am | 18 | 67% |
| AS 1574Alaska Airlines | 7:00am | 9:37am | 13 | 92% |
| DL 1015Delta Air Lines | 7:10am | 9:55am | 31 | 77% |
| UA 2101United Airlines | 9:00am | 11:51am | 10 | 91% |
| AS 375Alaska Airlines | 9:03am | 11:39am | 13 | 90% |
| AS 361Alaska Airlines | 9:30am | 12:16pm | 18 | 93% |
| UA 2241United Airlines | 1:10pm | 3:55pm | 10 | 87% |
| UA 2799United Airlines | 1:20pm | 4:06pm | 21 | 91% |
| UA 326United Airlines | 5:55pm | 8:46pm | 8 | 76% |
| UA 1128United Airlines | 6:00pm | 8:45pm | 18 | 61% |
| AS 737Alaska Airlines | 6:14pm | 9:09pm | 31 | 58% |
Is IAD to SEA on time?
From September 2025 to August 2026, 78% of 1,821 flights arrived within 15 minutes of schedule and 1% were cancelled. Flights leaving around 9am were the most punctual (91%), those around 6pm the least (64%). Most delay time was caused by the airline (crew, maintenance, cleaning, fuelling) (39%).
| Airline | Flights | On time | Average delay | Cancelled |
|---|---|---|---|---|
| Alaska Airlines | 835 | 75% | 14 min | 1.2% |
| United Airlines | 625 | 81% | 14 min | 0.5% |
| Delta Air Lines | 361 | 77% | 22 min | 1.4% |
Airlines as sold: flights operated by regional partners count under the airline on the ticket. Average delay is across all completed flights, early arrivals counted as zero.
On-time arrivals by departure time
| Scheduled departure | Flights | On time, relative | On time |
|---|---|---|---|
| 6am to 7am | 120 | 91% | |
| 7am to 8am | 568 | 75% | |
| 8am to 9am | 41 | 88% | |
| 9am to 10am | 256 | 91% | |
| 1pm to 2pm | 165 | 89% | |
| 5pm to 6pm | 372 | 74% | |
| 6pm to 7pm | 242 | 64% | |
| 7pm to 8pm | 57 | 54% |
Flights by month
| Month | Flights | Flights, relative | Passengers |
|---|---|---|---|
| August 2025 | 220 | 32,970 | |
| September 2025 | 179 | 23,255 | |
| October 2025 | 154 | 20,256 | |
| November 2025 | 116 | 14,679 | |
| December 2025 | 123 | 17,493 | |
| January 2026 | 100 | 12,793 | |
| February 2026 | 92 | 11,761 | |
| March 2026 | 114 | 16,825 | |
| April 2026 | 127 | 18,311 | |
| May 2026 | 201 | 29,953 | |
| June 2026 | 195 | 30,505 | |
| July 2026 | 210 | 33,706 |
Related
Source: US Department of Transportation, T-100 Segment data, August 2025 to July 2026.