Historical on-time performance
Boston to Seattle
2,496 miData through Dec 2025Source: US DOT · BTS
Flights on BOS–SEA arrive on time 74% of the time over the last 12 months.
On-time rate74%arrived within 15 min
p90 delay40 min1 in 10 flights is worse (tail risk)
Cancelled0.8%of scheduled flights
based on 2,438 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-time77%Medianon timep9035 minCancel0.8%Flights943
- Alaska AirlinesOn-time71%Medianon timep9040 minCancel0.9%Flights1,167
- JetBlue AirwaysOn-time77%Medianon timep9050 minCancel0.3%Flights328
Why flights run late
Delay causes
- Airline25%
- Weather2%
- Air traffic (NAS)31%
- Late aircraft41%
- Security1%
Most delay minutes here are attributed to Late aircraft.
Over time
On-time trend
By season
On-time rate by month
When to fly
Best time to fly BOS → SEA
All airlines · rolling 36 months (2023-01 .. 2025-12).
Best time of day
On-time rates are fairly even by time of day on this route — ranging from 71% to 82% on time.
- Middays82% on time · p90 25 min · 1,007 flights
- Mornings81% on time · p90 25 min · 3,158 flights
- Afternoons75% on time · p90 60 min · 633 flights
- Evenings71% on time · p90 60 min · 2,900 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 73% to 80% on time.
- Mondays80% on time · p90 35 min · 1,155 flights
- Wednesdays80% on time · p90 35 min · 1,069 flights
- Tuesdays79% on time · p90 35 min · 1,066 flights
- Saturdays77% on time · p90 40 min · 1,002 flights
- Sundays75% on time · p90 35 min · 1,129 flights
- Thursdays74% on time · p90 40 min · 1,133 flights
- Fridays73% on time · p90 50 min · 1,144 flights
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