IAD (Washington) to SEA (Seattle) flights arrive on time 81% of the time. The most reliable airline on this route is United Airlines at 84%. The average delay is 70 minutes. Delays on this route are most often caused by the airline (crew, maintenance, or boarding).
Source: Bureau of Transportation Statistics. Updated March 2026.IAD → SEA
IAD (Washington) to SEA (Seattle)
IAD → SEA on-time performance by month
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JanFebMarAprMayJunJulAugSepOctNovDec
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This route is on time most of the time. About 81% of flights arrive on schedule.
Delays on this route are most often caused by the airline (crew, maintenance, or boarding).
Accurate?
Airlines are roughly equal on this route — United Airlines leads slightly at 84% vs Alaska Airlines at 80%.
Airline Comparison
United Airlines leads at 84% on time; Alaska Airlines trails at 80%.
Accurate?
Good to know
Departing from IAD
83% on timeExpect ~19 min sitting on the taxiway after your gate pushes back. IAD has long runway queues.
TSA is currently ~5 min. Best time: 4 AM (about 5 min).
Arriving at SEA
82% on timeWhen flights into SEA are late, the average delay is 57 minutes. Build buffer if you have ground plans.
If connecting at SEA: TSA is ~10 min right now. Allow at least 60 minutes for a domestic connection.
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Data last updated March 2026. Source: Bureau of Transportation Statistics.