How often are ONT to SEA flights on time?

Flights from Ontario (ONT) to Seattle (SEA) arrive on time 91% of the time across 14,240 flights of official data.

Which airline is most reliable on the ONT to SEA route?

Delta Air Lines has the best on-time record on this route at 94% across 5,961 flights.

Route reliability

Flights from Ontario to Seattle arrive on time 91% of the time across 14,240 flights. Here’s how each airline really performs.

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On-time rate

14,240 flights

On-time = arrived within 15 minutes of schedule, per BTS TranStats. Compare the reverse leg SEA → ONT.

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Score real ONT–SEA flights on reliability, weather, and connection safety — not just price.