Historical on-time performance
Seattle to Ontario
956 miData through Dec 2025Source: US DOT · BTS
Flights on SEA–ONT arrive on time 80% of the time over the last 12 months.
On-time rate80%arrived within 15 min
p90 delay30 min1 in 10 flights is worse (tail risk)
Cancelled1.3%of scheduled flights
based on 2,450 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
- SkyWest AirlinesbestOn-time90%Medianon timep9010 minCancel0.2%Flights1,107
- Alaska AirlinesOn-time72%Medianon timep9035 minCancel2.2%Flights1,251
- Frontier AirlinesOn-time68%Medianon timep9065 minCancel2.2%Flights92
Why flights run late
Delay causes
- Airline46%
- Weather6%
- Air traffic (NAS)15%
- Late aircraft33%
- Security0%
Most delay minutes here are attributed to Airline.
Over time
On-time trend
By season
On-time rate by month
When to fly
Best time to fly SEA → ONT
All airlines · rolling 36 months (2023-01 .. 2025-12).
Best time of day
Mornings are the most reliable time of day to fly this route — 88% on time.
- Mornings88% on time · p90 15 min · 1,943 flights
- Afternoons82% on time · p90 30 min · 1,419 flights
- Evenings80% on time · p90 30 min · 1,527 flights
- Middays77% on time · p90 30 min · 1,570 flights
- Overnights68% on time · p90 50 min · 989 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 76% to 85% on time.
- Tuesdays85% on time · p90 20 min · 993 flights
- Saturdays84% on time · p90 20 min · 940 flights
- Wednesdays83% on time · p90 25 min · 989 flights
- Mondays80% on time · p90 30 min · 1,142 flights
- Fridays78% on time · p90 35 min · 1,116 flights
- Thursdays77% on time · p90 35 min · 1,124 flights
- Sundays76% on time · p90 30 min · 1,144 flights
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