Ontario (ONT) to Atlanta (ATL): On-Time Performance
Data through May 2026
The calendar drives reliability on ONT–ATL. September 2025 flights landed on schedule 97% of the time, but January 2026 dropped to 77% — a gap of 20 points. Across the full period the route averages 90% on-time against a national 78%.
- On-time
- 90%
- arrived <15 min late
- Avg delay
- 8 min
- completed flights
- Cancelled
- 1.7%
- Flights/day
- 2.6
- last 12 months
- Duration
- 4h 13m
- scheduled
- Distance
- 1,900 mi
Monthly on-time trend
Best time to fly from ONT to ATL
Aim for departures around 7 a.m. (94% on-time); avoid 12 p.m. departures (83%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 90% | 7 min |
| Tuesdaybest | 92% | 4 min |
| Wednesday | 91% | 8 min |
| Thursdaybest | 92% | 7 min |
| Friday | 90% | 10 min |
| Saturday | 91% | 8 min |
| Sunday | 88% | 12 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft29%
- Airline operations54%
- National airspace system11%
- Weather4%
- Security1%
Frequently asked questions
- How often are flights from ONT to ATL delayed?
- 10% of ONT–ATL flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 8 minutes.
- What is the best time of day to fly from ONT to ATL?
- Departures around 7 a.m. have the best record (94% on-time), while departures around 12 p.m. have the worst (83%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from ONT to ATL?
- The scheduled ONT–ATL flight time averages 4h 13m over 1,900 miles. Actual arrival times vary — flights on this route land 15+ minutes late 10% of the time.
- How often are ONT to ATL flights cancelled?
- 1.7% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, slightly above the national rate of 1.6%.
- What is the worst month to fly from ONT to ATL?
- January 2026 was the roughest month in this dataset, with only 77% of arrivals on time. The best was September 2025 at 97%. If your dates are flexible, that 20-point gap is worth planning around.
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Based on 1,866 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.