PlainFlights

Route · ATL → ONT · 2020–2025 BTS data

Atlanta to Ontario

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), ATL to ONT (Atlanta to Ontario) ranks #2518 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

80.5%
On-time
+1.5 pts
vs US avg
59 min
Delay when late
4,903
Flights
#2518 of 4927
Corpus placement

Cancelled

1.2%

Best Month

Oct 2024 95%

Worst Month

May 2024 56%

Distance

1,900 mi

Carriers

2

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 88 23 4 0 DL
Nov 2025 84 14 1 0 DL
Oct 2025 85 17 0 0 DL
Sep 2025 77 13 0 0 DL
Aug 2025 82 19 1 0 DL
Jul 2025 88 24 1 0 DL
Jun 2025 84 33 2 0 DL
May 2025 81 25 0 0 DL
Apr 2025 77 16 0 0 DL
Mar 2025 62 12 1 1 DL
Feb 2025 56 15 0 0 DL
Jan 2025 66 13 4 1 DL
Dec 2024 88 19 0 1 DL
Nov 2024 77 18 0 1 DL
Oct 2024 84 4 0 0 DL
Sep 2024 80 11 0 0 DL
Aug 2024 85 18 0 0 DL
Jul 2024 82 32 9 0 DL
Jun 2024 87 17 0 0 DL
May 2024 79 35 0 0 DL
Apr 2024 72 22 0 0 DL
Mar 2024 62 10 0 0 DL
Feb 2024 58 7 0 1 DL
Jan 2024 63 10 0 0 DL

ATL–ONT seasonal on-time pattern

Best: October (90.5%) · weakest: June (65.5%)

60%70%80%90%100% JanFebMarAprMayJunJulAugSepOctNovDec 80.9%

Strongest calendar month

October

90.5% on-time · ~72 flights/mo

Busiest calendar month

June

~83 flights/mo avg

Weakest calendar month

June

65.5% on-time · ~83 flights/mo

Cancellation Rate

1.2%

23 of 1,847 flights

Diversion Rate

0.3%

5 of 1,847 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

ATL - Atlanta

Full on-time, delay-cause, and seasonal performance for Atlanta, GA.

ATL on-time profile

ONT - Ontario

Full on-time, delay-cause, and seasonal performance for Ontario, CA.

ONT on-time profile

Compare the two airports

See ATL and ONT side by side on delays, cancellations, and reliability.

Compare ATL vs ONT

Origin-hub reliability standing

Mid-pack among ATL departures

From ATL, this corridor sits with 75 other 75–85% on-time routes out of 144 tracked departures, not the hub's reliability leaders (67 at ≥85%) and not the softest ( 2 below 75%). Destination: Ontario · fleet on-time rank #2903 of 4927.

What the Data Says About ATL to ONT

4,903 tracked flights put the ATL to ONT pairing (Atlanta to Ontario) at a 80.5% on-time rate, squarely in line with the wider network. Delays that do occur run 59.3 minutes on average. Across the 1,900-mile route and its 2 carriers, the trailing 24 months show 1.2% cancelled and 0.3% diverted (1,847 flights sampled).

The monthly split is wide on this route: Oct 2024 posted the strongest performance at 95% on-time, while May 2024 came in at just 56% - a 40-point swing worth factoring into travel timing.

On the multi-year calendar, ATL–ONT peaks in October at 90.5% on-time while June carries the heaviest traffic (~83 flights per month) ; the softest month is June at 65.5%, a 25.0-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does ATL to ONT rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, ATL to ONT ranks #2518 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from ATL to ONT? ▼
Flights from Atlanta to Ontario have a 80.5% on-time rate based on 4,903 flights. The average delay is 59.3 minutes. The best recent month was Oct 2024 with 95% on-time.
What is the cancellation rate for ATL to ONT? ▼
Over the last 24 months, 1.2% of flights on this route were cancelled (23 of 1,847 flights) and 0.3% were diverted.
How far is the flight from ATL to ONT? ▼
The flight distance from Atlanta (ATL) to Ontario (ONT) is approximately 1,900 miles. This route is served by 2 carriers.
When is the best time to fly from ATL to ONT? ▼
The best recent month for on-time performance was Oct 2024 (95% on-time). The worst was May 2024 (56% on-time). Consider booking during months with historically better performance.

Airports on this route

ATL Airport

Atlanta
ONT Airport

Ontario
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using ATL–ONT data

ATL–ONT is mid-pack at 80.5% on-time; month and carrier mix move more than the corridor headline.

  • Compare ATL and ONT airport profiles: delay causes and top routes differ even on the same corridor. ATL airport
  • If your dates flex, October (90.5% on-time) beats June (65.5%) on this corridor. Seasonal chart
  • 4 other routes post a similar 80.5% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.