Seattle (SEA) to Dulles (IAD) flights
Alaska Airlines, United Airlines, Delta Air Lines fly nonstop from Seattle-Tacoma International Airport to Washington Dulles International Airport, with about 48 flights a week in July 2026. The 2,305-mile flight takes about 4h 51m gate to gate.
- Distance
- 2,305 mi · 3,710 km
- Flight time
- 4h 51m
- Airlines
- 3
- Seats filled
- 86%
Airlines flying SEA to IAD
| Airline | Flights a week | Aircraft | Passengers (12 months) | Flight time |
|---|---|---|---|---|
| Alaska Airlines | 21 | Boeing 737-900ER, Boeing 737 MAX 9, Boeing 737-800 | 127,710 | 4h 50m |
| United Airlines | 20 | Boeing 737 MAX 9, Boeing 737 MAX 8, Boeing 737-900ER | 100,795 | 4h 53m |
| Delta Air Lines | 7 | Airbus A220-300, Airbus A220-100 | 35,366 | 4h 51m |
Airlines are the operating carrier: regional airlines such as SkyWest or Horizon often fly under a larger airline's brand.
SEA to IAD flight schedule
10 flight numbers flew this route in August 2026, 4 of them almost daily. The first usually leaves at 8:10am and the last at 11:20pm. 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) |
|---|---|---|---|---|
| UA 1523United Airlines | 8:10am | 4:16pm | 21 | 91% |
| UA 2463United Airlines | 8:15am | 4:24pm | 10 | 91% |
| AS 737Alaska Airlines | 9:13am | 5:11pm | 31 | 83% |
| UA 2131United Airlines | 1:00pm | 9:06pm | 10 | 91% |
| AS 675Alaska Airlines | 3:56pm | 11:59pm | 13 | 100% |
| DL 541Delta Air Lines | 3:58pm | 11:59pm | 31 | 77% |
| AS 406Alaska Airlines | 4:01pm | 11:59pm | 18 | 82% |
| AS 367Alaska Airlines | 10:43pm | 6:39am | 31 | 83% |
| UA 2467United Airlines | 11:04pm | 7:07am | 18 | 78% |
| UA 264United Airlines | 11:20pm | 7:22am | 8 | 89% |
Is SEA to IAD on time?
From September 2025 to August 2026, 85% of 1,822 flights arrived within 15 minutes of schedule and 0.6% were cancelled. Flights leaving around 1pm were the most punctual (91%), those around 4pm the least (78%). Most delay time was caused by the airline (crew, maintenance, cleaning, fuelling) (49%).
| Airline | Flights | On time | Average delay | Cancelled |
|---|---|---|---|---|
| Alaska Airlines | 835 | 83% | 7 min | 0.4% |
| United Airlines | 626 | 91% | 7 min | 0.6% |
| Delta Air Lines | 361 | 77% | 20 min | 1.1% |
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 |
|---|---|---|---|
| 8am to 9am | 480 | 91% | |
| 9am to 10am | 172 | 83% | |
| 10am to 11am | 74 | 86% | |
| 1pm to 2pm | 123 | 91% | |
| 3pm to 4pm | 243 | 81% | |
| 4pm to 5pm | 269 | 78% | |
| 9pm to 10pm | 117 | 83% | |
| 10pm to 11pm | 167 | 81% | |
| 11pm to 12am | 174 | 87% |
Flights by month
| Month | Flights | Flights, relative | Passengers |
|---|---|---|---|
| August 2025 | 222 | 35,464 | |
| September 2025 | 179 | 25,187 | |
| October 2025 | 153 | 19,972 | |
| November 2025 | 118 | 15,045 | |
| December 2025 | 126 | 17,883 | |
| January 2026 | 99 | 12,631 | |
| February 2026 | 94 | 12,109 | |
| March 2026 | 115 | 16,700 | |
| April 2026 | 128 | 18,722 | |
| May 2026 | 200 | 27,681 | |
| June 2026 | 196 | 29,664 | |
| July 2026 | 211 | 32,813 |
Related
Source: US Department of Transportation, T-100 Segment data, August 2025 to July 2026.