Dulles (IAD) to Seattle (SEA)
Flight time
≈ 5h 24m
Bearing
300° NW
Dulles (IAD) to Seattle (SEA) is 2,300 miles (3,702 km) as the crow flies — the great-circle baseline most distance-based mileage programs credit.
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What actually flies IAD–SEA
US DOT T-100 · filed dataIn April 2026, Alaska Airlines operated the most departures, one of 3 carriers flying nonstop IAD–SEA; the Boeing 737 MAX 9 was the most common aircraft at 45% of departures; flights ran 87% full.
Departures
255
April 2026
Seats
42,575
both directions
Passengers
37,033
both directions
Load factor
87.0%
passengers ÷ seats
Who flies IAD–SEA?
Alaska Airlines operated the most nonstop IAD–SEA departures in April 2026 (133), one of 3 carriers on the route.
- AS
Alaska Airlines
133 departures · 23,606 seats
Share of departures52.2%85.3%
Load
- UA
United Airlines
64 departures · 11,430 seats
Share of departures25.1%92.5%
Load
- DL
Delta Air Lines
58 departures · 7,539 seats
Share of departures22.7%83.9%
Load
What plane flies IAD–SEA?
In April 2026, the Boeing 737 MAX 9 flew 45% of IAD–SEA departures — more than any other aircraft type.
- Boeing 737 MAX 9
114 departures · 89.3% load
44.7% - Boeing 737-900ER
77 departures · 86.1% load
30.2% - Airbus A220-300
58 departures · 83.9% load
22.8% - Boeing 737 MAX 8
4 departures · 71.0% load
1.6% - Boeing 737-800
2 departures · 84.5% load
0.8%
How has IAD–SEA traffic changed?
Nonstop IAD–SEA departures fell from 406 in May 2025 to 255 in April 2026.
Monthly nonstop IAD–SEA traffic, trailing 12 months through April 2026. Bars scale to the busiest month; months with no filed service show as zero.
May 2025
406 departures · 58,279 passengers
85.2%
Load
June 2025
471 departures · 70,105 passengers
88.0%
Load
July 2025
485 departures · 75,213 passengers
90.8%
Load
August 2025
442 departures · 68,434 passengers
91.5%
Load
September 2025
358 departures · 48,442 passengers
80.5%
Load
October 2025
307 departures · 40,228 passengers
79.2%
Load
November 2025
234 departures · 29,724 passengers
78.5%
Load
December 2025
249 departures · 35,376 passengers
86.2%
Load
January 2026
199 departures · 25,424 passengers
78.7%
Load
February 2026
186 departures · 23,870 passengers
79.0%
Load
March 2026
229 departures · 33,525 passengers
89.6%
Load
April 2026
255 departures · 37,033 passengers
87.0%
Load
By direction
The DOT files each direction separately — they rarely match.
SEA → IAD
87.6% full
128 departures · 18,722 passengers
IAD → SEA
86.4% full
127 departures · 18,311 passengers
Nonstop IAD–SEA traffic has been filed with the US DOT since 2025.
Source: US DOT BTS Form 41 T-100 Segment (All Carriers). Data through April 2026; filings from 2025. Public domain (US Government work). The DOT publishes roughly three months in arrears.
The airports
Frequently asked
How far is Dulles (IAD) from Seattle (SEA)?
IAD to SEA is 2,300 miles (3,702 km / 1,999 nautical miles) measured great-circle — the shortest path over the surface of the Earth.
How long is the flight from IAD to SEA?
A nonstop covers the 2,300-mile great-circle distance in roughly 5h 24m of block time, before winds. Actual schedules vary a few percent by direction and aircraft.
What plane flies IAD–SEA?
In April 2026, the Boeing 737 MAX 9 flew the largest share of departures (44.7%), followed by the Boeing 737-900ER (30.2%).
What mileage do I earn flying IAD–SEA?
Distance-based programs credit off the 2,300-mile great-circle figure, then apply your fare-class earning rate. Revenue-based programs credit off the fare instead.
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