Historical on-time performance
Ontario to Seattle
956 miData through May 2026Source: US DOT · BTS
Flights on ONT–SEA arrive on time 85% of the time over the last 12 months.
On-time rate85%arrived within 15 min
p90 delay20 min1 in 10 flights is worse (tail risk)
Cancelled1.3%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-time92%Medianon timep9010 minCancel0.3%Flights1,113
- Frontier AirlinesOn-time88%Medianon timep9020 minCancel0.0%Flights92
- Alaska AirlinesOn-time80%Medianon timep9030 minCancel2.2%Flights1,264
Why flights run late
Delay causes
- Airline44%
- Weather6%
- Air traffic (NAS)17%
- Late aircraft33%
- Security0%
Most delay minutes here are attributed to Airline.
When flights don't go
Why flights were cancelled
- Airline68%
- Weather10%
- Air traffic (NAS)23%
- Security0%
Most cancellations here are attributed to Airline. Shares are among 31 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 ONT → SEA
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 — 91% on time.
- Mornings91% on time · p90 10 min · 2,316 flights
- Middays87% on time · p90 20 min · 2,051 flights
- Afternoons82% on time · p90 25 min · 1,477 flights
- Evenings81% on time · p90 35 min · 1,278 flights
- Overnights76% on time · p90 40 min · 340 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 83% to 87% on time.
- Saturdays87% on time · p90 15 min · 956 flights
- Tuesdays87% on time · p90 15 min · 992 flights
- Wednesdays87% on time · p90 20 min · 987 flights
- Mondays85% on time · p90 20 min · 1,130 flights
- Sundays85% on time · p90 20 min · 1,149 flights
- Thursdays85% on time · p90 25 min · 1,127 flights
- Fridays83% on time · p90 25 min · 1,121 flights
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