Route on-time record
ATL to ONT: most on-time flights and the best time to fly
Atlanta (Hartsfield Jackson Atlanta International Airport) to Ontario (Ontario International Airport). 941 nonstop flights in Jun 2025 to May 2026, 76% arrived within 15 minutes and 1.7% were cancelled. The most reliable flight number was Delta 665 at 9:57 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
ATL → ONT
Atlanta to Ontario: 941 nonstop flights a year
On time (12 months)
76%
Cancelled
1.7%
avg delay 14 min
Best time to leave
Before 9 AM
89% on time vs 51% after 9 PM
Most reliable airline
Delta
74% chance on time
Fares open on our travel partner (Aviasales). Pick the flight number you chose here.
Most reliable nonstop flights
Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.
#1 · Delta 665
9:57 AM → 11:47 AM4h 43m nonstop
Local times, typical schedule. Last flown 2026-05-31.
84%
chance on time
- On time (history)
- 86%
- Cancelled
- 2.2%
- Avg arrival delay
- 8 min
- Arrived on time 86% of the time (357 flights, Jun 2025 to May 2026).
- Departs outside ATL's trouble window (1 PM to 7 PM, when 59% of its 96 ground stops and delay programs started).
Strong track record · 357 flights
Find Delta 665 fares Opens this date on Aviasales#2 · Delta 761
7:14 PM → 9:00 PM4h 46m nonstop
Local times, typical schedule. Last flown 2026-04-12.
75%
chance on time
- On time (history)
- 78%
- Cancelled
- 0.0%
- Avg arrival delay
- 12 min
- Arrived on time 78% of the time (60 flights, Jun 2025 to May 2026).
- Never cancelled in 60 scheduled flights.
- Departs outside ATL's trouble window (1 PM to 7 PM, when 59% of its 96 ground stops and delay programs started).
Moderate track record · 60 flights
Find Delta 761 fares Opens this date on Aviasales#3 · Delta 779
8:10 PM → 9:48 PM4h 38m nonstop
Local times, typical schedule. Last flown 2026-05-31.
68%
chance on time
- On time (history)
- 67%
- Cancelled
- 1.2%
- Avg arrival delay
- 21 min
- Arrived on time 67% of the time (254 flights, Jun 2025 to May 2026).
- Departs outside ATL's trouble window (1 PM to 7 PM, when 59% of its 96 ground stops and delay programs started).
Strong track record · 254 flights
Find Delta 779 fares Opens this date on Aviasales#4 · Delta 745
4:59 PM → 6:36 PM4h 37m nonstop
Local times, typical schedule. Last flown 2026-05-31.
65%
chance on time
- On time (history)
- 60%
- Cancelled
- 0.0%
- Avg arrival delay
- 15 min
- Arrived on time 60% of the time (25 flights, Jun 2025 to May 2026).
- Departs inside ATL's trouble window: 59% of its 96 ground stops and delay programs started between 1 PM and 7 PM.
- Short track record (25 flights), so its score leans on the airline's record at this hour.
Limited track record · 25 flights
Find Delta 745 fares Opens this date on Aviasales#5 · Delta 2891
4:53 PM → 6:33 PM4h 40m nonstop
Local times, typical schedule. Last flown 2026-05-06.
59%
chance on time
- On time (history)
- 46%
- Cancelled
- 0.0%
- Avg arrival delay
- 20 min
- Arrived on time 46% of the time (24 flights, Jun 2025 to May 2026).
- Departs inside ATL's trouble window: 59% of its 96 ground stops and delay programs started between 1 PM and 7 PM.
- Short track record (24 flights), so its score leans on the airline's record at this hour.
Limited track record · 24 flights
Find Delta 2891 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- Delta Air Lines74%
941 flights · 76% on time as flown · 1.7% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM89%
57 flights · avg delay 4 min
- 9 AM to noon85%
308 flights · avg delay 9 min
- 3 to 6 PM71%
212 flights · avg delay 13 min
- 6 to 9 PM73%
287 flights · avg delay 17 min
- After 9 PM51%
77 flights · avg delay 37 min
Best day: Wednesday (78%). Worst: Sunday (72%).
Smarter routing
Nearby airports that run more on time
ATL → LAX 77% chance on time
Hartsfield Jackson Atlanta International Airport to Los Angeles International Airport · 5,097 flights a year · 47 mi from your airports · yours: 74%
On time by month
All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.
What delays this route
- Airline (crew, maintenance, boarding)49%
- Late-arriving aircraft22%
- Air traffic control and airport volume21%
- Severe weather7%
Share of delay minutes by the cause airlines report to the US DOT.
Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure
ATL to ONT questions
- What time of day is best to fly ATL to ONT?
- Before 9 AM: 89% of flights arrived on time, against 51% for departures after 9 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from ATL to ONT?
- Delta, with a season-adjusted 74% chance of operating and arriving on time over 941 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
- What is the worst month for delays on ATL to ONT?
- June (58% on time); the best was October (89%), averaged over Jun 2023 to May 2026.
- Is this a prediction for my flight?
- No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.
More routes from ATL
- ONT to ATL (return)
- ATL to LGA 73%
- ATL to MCO 69%
- ATL to FLL 69%
- ATL to DCA 69%
- ATL to DFW 73%
- ATL to ORD 71%
- ATL to EWR 72%
- ATL to MIA 70%
- ATL to TPA 71%
- ATL to PHL 73%
- ATL to DEN 76%
- ATL to BWI 74%
Live status: FAA delays and ground stops