Historical on-time performance
Atlanta to Ontario
1,900 miData through May 2026Source: US DOT · BTS
Flights on ATL–ONT arrive on time 74% of the time over the last 12 months.
On-time rate74%arrived within 15 min
p90 delay45 min1 in 10 flights is worse (tail risk)
Cancelled1.7%of scheduled flights
based on 941 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
- Delta Air LinesOn-time74%Medianon timep9045 minCancel1.7%Flights941
Why flights run late
Delay causes
- Airline49%
- Weather7%
- Air traffic (NAS)21%
- Late aircraft22%
- Security0%
Most delay minutes here are attributed to Airline.
When flights don't go
Why flights were cancelled
- Airline63%
- Weather38%
- Air traffic (NAS)0%
- Security0%
Most cancellations here are attributed to Airline. Shares are among 16 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 ATL → 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 — 84% on time.
- Mornings84% on time · p90 20 min · 1,019 flights
- Middays76% on time · p90 35 min · 140 flights · limited
- Evenings72% on time · p90 50 min · 749 flights
- Overnights66% on time · p90 55 min · 874 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 70% to 78% on time.
- Wednesdays78% on time · p90 35 min · 396 flights
- Tuesdays77% on time · p90 35 min · 391 flights
- Thursdays76% on time · p90 35 min · 428 flights
- Saturdays75% on time · p90 45 min · 367 flights
- Mondays73% on time · p90 45 min · 425 flights
- Fridays72% on time · p90 50 min · 429 flights
- Sundays70% on time · p90 60 min · 427 flights
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