ATL to ONT flight delays & on-time performance
Nonstop flights from Hartsfield Jackson Atlanta International Airport to Ontario International Airport · 1,900 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at ATL or ONT right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from Atlanta (ATL) to Ontario (ONT) arrived on time 75% of the time in Aug 2025 – Jul 2026, worse than the 78% national average.
- 1.7% were cancelled, and 7% arrived an hour or more late.
- Delta Air Lines is the only airline reporting nonstop flights on this route.
- Departures scheduled around 8am did best (89% on time); around 4pm did worst (59%).
- Wednesday was the most reliable day to fly (82% on time) and Friday the least (72%).
- The largest source of delay minutes was airline (crew, maintenance, cleaning, fueling) (46%).
Which airline is most on time from ATL to ONT?
Ranked by on-time arrival rate. Regional airlines fly under their partner's brand (e.g. SkyWest for Delta Connection or United Express).
| Airline | On time | Cancelled | Avg delay | 1 hr+ late | Flights |
|---|---|---|---|---|---|
| Delta Air Lines | 75% | 1.7% | 14 min | 7.4% | 937 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 8am89%56 flights
- 9am85%285 flights
- 10am70%24 flights
- 4pm59%85 flights
- 5pm72%160 flights
- 6pm71%18 flights
- 7pm77%122 flights
- 8pm71%133 flights
- 9pm60%54 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday74%0.7% cancelled
- Tuesday77%1.5% cancelled
- Wednesday82%0.8% cancelled
- Thursday75%1.5% cancelled
- Friday72%1.4% cancelled
- Saturday76%3.4% cancelled
- Sunday73%2.9% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Airline (crew, maintenance, cleaning, fueling)46%
- Late-arriving aircraft26%
- Air traffic control & airport congestion22%
- Extreme weather6%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Airline (crew, maintenance, cleaning, fueling)81%
- Extreme weather19%
- Air traffic control & airport congestion0%
- Security0%
ATL to ONT: common questions
- How often are ATL to ONT flights on time?
- 75% of flights arrived less than 15 minutes late in Aug 2025 – Jul 2026, compared with 78% for all US flights.
- How often are flights from Atlanta to Ontario cancelled?
- 1.7% of scheduled flights were cancelled (16 of 937).
- How long are typical delays?
- Across all flights the average arrival delay was 14 min (early arrivals count as zero). Flights that were late arrived 51 min behind schedule on average, and 7.4% of flights were an hour or more late.
- How long is taxi time at ATL?
- Flights on this route spent 17 min taxiing from the gate to takeoff on average.
Related routes
Return trip: ONT to ATL — 89% on time
More flights from Atlanta
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: ATL → ONT, nonstop flights by US airlines that report to the DOT. How we calculate this.