Historical on-time performance
Seattle to Ontario
956 miData through May 2026Source: US DOT · BTS
Flights on SEA–ONT arrive on time 81% of the time over the last 12 months.
On-time rate81%arrived within 15 min
p90 delay30 min1 in 10 flights is worse (tail risk)
Cancelled1.2%of scheduled flights
based on 2,469 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
- SkyWest AirlinesbestOn-time89%Medianon timep9015 minCancel0.4%Flights1,112
- Alaska AirlinesOn-time74%Medianon timep9035 minCancel1.9%Flights1,265
- Frontier AirlinesOn-time68%Medianon timep9065 minCancel2.2%Flights92
Why flights run late
Delay causes
- Airline49%
- Weather7%
- Air traffic (NAS)13%
- Late aircraft31%
- Security1%
Most delay minutes here are attributed to Airline.
When flights don't go
Why flights were cancelled
- Airline67%
- Weather10%
- Air traffic (NAS)23%
- Security0%
Most cancellations here are attributed to Airline. Shares are among 30 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 SEA → ONT
All airlines · rolling 36 months (2023-06 .. 2026-05).
Best time of day
Mornings are the most reliable time of day to fly this route — 88% on time.
- Mornings88% on time · p90 10 min · 1,904 flights
- Afternoons82% on time · p90 25 min · 1,433 flights
- Evenings82% on time · p90 25 min · 1,370 flights
- Middays78% on time · p90 30 min · 1,702 flights
- Overnights70% on time · p90 45 min · 1,057 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 78% to 86% on time.
- Tuesdays86% on time · p90 20 min · 994 flights
- Saturdays84% on time · p90 20 min · 956 flights
- Wednesdays83% on time · p90 25 min · 987 flights
- Mondays81% on time · p90 30 min · 1,132 flights
- Fridays79% on time · p90 30 min · 1,122 flights
- Thursdays78% on time · p90 35 min · 1,126 flights
- Sundays78% on time · p90 30 min · 1,149 flights
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