Which airline is most reliable for ATL (Atlanta) to ONT (Ontario)?

The most reliable airline on the ATL to ONT route is Delta Air Lines, with an on-time arrival rate of 77%.

How often are flights delayed from ATL to ONT?

About 24% of flights from ATL to ONT experience delays. 76% arrive on time.

What's the average delay on ATL to ONT flights?

When flights from ATL to ONT are delayed, the average delay is approximately 55 minutes.

Is a short connection safe after a ATL to ONT flight?

With 76% of ATL to ONT flights arriving on time and an average delay of 55 minutes when late, a connection under 60 minutes at ONT is risky. We recommend at least 75-90 minutes for domestic connections after this route.

ATL → ONT

ATL (Atlanta) to ONT (Ontario)

ATL (Atlanta) to ONT (Ontario) flights arrive on time 76% of the time. The most reliable airline on this route is Delta Air Lines at 77%. The average delay is 55 minutes. Delays on this route are most often caused by the airline (crew, maintenance, or boarding).

Source: Bureau of Transportation Statistics. Updated October 2026.

ATL → ONT on-time performance by month

JanFebMarAprMayJunJulAugSepOctNovDec

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This route is on time most of the time. About 76% of flights arrive on schedule.

Delays on this route are most often caused by the airline (crew, maintenance, or boarding).

Accurate?

Delta Air Lines is significantly more reliable on this route at 77% on time vs Frontier Airlines at 38%.

Airline Comparison

Delta Air Lines leads at 77% on time; Frontier Airlines trails at 38%.

Accurate?

Good to know

Departing from ATL

81% on time

Expect ~17 min sitting on the taxiway after your gate pushes back. ATL has long runway queues.

TSA is currently ~27 min. Best time: 4 AM (about 5 min).

More about ATL →

Arriving at ONT

81% on time

When flights into ONT are late, the average delay is 64 minutes. Build buffer if you have ground plans.

If connecting at ONT: TSA is ~14 min right now. Allow at least 60 minutes for a domestic connection.

More about ONT →Connection times at ONT →

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ATL Airport ONT Airport

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Data last updated October 2026. Source: Bureau of Transportation Statistics.