Best Time to Fly ONT to ATL: On-Time Stats by Hour & Airline
Ontario International → Hartsfield-Jackson Atlanta International
Data through July 2026 · Last updated October 18, 2026
937 flights were scheduled from Ontario (ONT) to Atlanta (ATL) in the last 12 months, and 89.3% of those that flew arrived on time, 11.7 points above the US average of 77.6%.
Delta Air Lines was the only reporting airline with regular flights on this route.
Over 24 months, Thursday was the most reliable day (93% on time) and January the worst month (84%).
The cancellation rate was 1.8% (US average 1.8%).
ONT to ATL on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| Delta Air Lines | 89.3% | 97 min | 1.8% | 937 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly ONT to ATL
On-time arrival % by scheduled departure hour (local time), 1,865 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 6am–7am | 93.0% | 0.0% | 57 |
| 7am–8am | 93.0% | 1.6% | 574 |
| 11am–12pm | 89.1% | 0.8% | 358 |
| 12pm–1pm | 83.3% | 0.7% | 286 |
| 1pm–2pm | 89.0% | 3.5% | 86 |
| 10pm–11pm | 93.3% | 1.6% | 504 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on ONT to ATL
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | 94.6% | +4.0 pts | 2.6% | 38 |
| Christmas & New Year (Dec 20 - Jan 3) | 92.3% | +1.7 pts | 4.9% | 82 |
| Summer peak (Jun 15 - Aug 15) | 90.2% | -0.4 pts | 1.7% | 349 |
| All other days | 90.6% | — | 1.0% | 1,396 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).