SEA (Seattle) to IAD (Washington) flights arrive on time 83% of the time. The most reliable airline on this route is United Airlines at 89%. The average delay is 58 minutes. Delays on this route are most often caused by the airline (crew, maintenance, or boarding).
Source: Bureau of Transportation Statistics. Updated August 2026.SEA → IAD
SEA (Seattle) to IAD (Washington)
SEA → IAD on-time performance by month
24
25
26
JanFebMarAprMayJunJulAugSepOctNovDec
Worse
Better
This route is on time most of the time. About 83% of flights arrive on schedule.
Delays on this route are most often caused by the airline (crew, maintenance, or boarding).
Accurate?
United Airlines edges out Alaska Airlines on this route — 89% vs 80% on time.
Airline Comparison
United Airlines leads at 89% on time; Alaska Airlines trails at 80%.
Accurate?
Good to know
Departing from SEA
80% on timeExpect ~21 min sitting on the taxiway after your gate pushes back. SEA has long runway queues.
TSA is currently ~25 min. Best time: 4 AM (about 5 min).
Arriving at IAD
82% on timeWhen flights into IAD are late, the average delay is 75 minutes. Build buffer if you have ground plans.
If connecting at IAD: TSA is ~8 min right now. Allow at least 60 minutes for a domestic connection.
Flight cancelled or delayed?
Check what United Airlines owes you — refund rights, action plan, complaint email. Free.
Flying out of SEA? We'll brief you.
Delays, TSA, weather, gates — we'll let you know if something matters.
Know someone flying soon?
Send them the link — delay data, TSA waits, weather, all free.
Data last updated August 2026. Source: Bureau of Transportation Statistics.