Historical on-time performance
Washington to Seattle
Flights on IAD–SEA arrive on time 75% of the time over the last 12 months.
based on 1,842 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
Too close to call — no single carrier is clearly more on-time here.
- Delta Air LinesOn-time79%Medianon timep9040 minCancel1.3%Flights305
- United AirlinesOn-time78%Medianon timep9030 minCancel0.6%Flights702
- Alaska AirlinesOn-time71%Medianon timep9045 minCancel1.1%Flights835
Why flights run late
Delay causes
- Airline41%
- Weather10%
- Air traffic (NAS)29%
- Late aircraft20%
- Security1%
Most delay minutes here are attributed to Airline.
When flights don't go
Why flights were cancelled
- Airline59%
- Weather41%
- Air traffic (NAS)0%
- Security0%
Most cancellations here are attributed to Airline. Shares are among 17 cancellations with a reported cause (BTS reports causes from June 2003).
Over time
On-time trend
By season
On-time rate by month
When to fly
Best time to fly IAD → SEA
All airlines · rolling 36 months (2023-06 .. 2026-05).
Best time of day
Middays are the most reliable time of day to fly this route — 92% on time.
- Middays92% on time · p90 5 min · 445 flights
- Mornings84% on time · p90 25 min · 2,749 flights
- Afternoons81% on time · p90 25 min · 167 flights · limited
- Evenings71% on time · p90 50 min · 2,716 flights
- Overnights69% on time · p90 50 min · 268 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 76% to 81% on time.
- Wednesdays81% on time · p90 30 min · 876 flights
- Tuesdays81% on time · p90 25 min · 870 flights
- Thursdays78% on time · p90 40 min · 933 flights
- Saturdays78% on time · p90 30 min · 865 flights
- Fridays78% on time · p90 40 min · 941 flights
- Mondays76% on time · p90 40 min · 931 flights
- Sundays76% on time · p90 40 min · 929 flights
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