How often are SEA to ONT flights on time?

Flights from Seattle (SEA) to Ontario (ONT) arrive on time 87% of the time across 14,243 flights of official data.

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

Delta Air Lines has the best on-time record on this route at 92% across 5,964 flights.

Route reliability

Flights from Seattle to Ontario arrive on time 87% of the time across 14,243 flights. Here’s how each airline really performs.

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On-time rate

14,243 flights

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

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