SEA → ONTSeattle to Ontario

live

Direct flights from Seattle (SEA) to Ontario (ONT): 19 nonstop departures observed each week across 3 airlines. 88% of the last 8 operated flights arrived within 15 minutes of schedule. The median arrival is 5 minutes early. No cancellations were recorded across the 8 tracked flights. The nonstop covers 1,540 km, an estimated 2 hours 28 minutes in the air. Measured by Pro Flight Search from live flight boards at Seattle and Ontario. Updated 20 October 2026 at 06:18 UTC.

SEA Seattle smooth · +13
ONT Ontario smooth · +0
1,540 km · ~2h 28m est.
dep bank 07:30–21:0619x weekly
Runs reliable · 3 airlines · 19x weekly · nonstop
88% on time

of the last 8 operated SEA → ONT flights arrived within 15 minutes

Median arrival delay is −5 min. 0 of 8 tracked legs cancelled in the sample. Will a delayed flight be cancelled? →

Median arrival−5 minacross the last 8 operated legs
Flight time~2h 28mestimated from route distance
Weekly departures19x3 direct airlines on the leg

The week

scheduled departures · origin local time
06121824
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Alaska AirlinesDelta Air LinesFrontier Airlines

Each mark is a scheduled departure at its origin-local time, observed operating in the last 7 days. Today is highlighted.

Who flies it

observed on the boards · 7 days
Alaska AirlinesAS

Flights AS476 07:30 Mo Tu We Fr Sa Su · AS571 10:31 daily · AS592 15:28 daily · AS489 21:06 Mo Th Fr Su

Delta Air LinesDL

Flights DL4070 08:25 Mo Tu We Th Fr Su · DL4031 14:30 daily · DL3987 19:56 daily

Frontier AirlinesF9

Flights F92276 varies Mo We Th Fr Su

History

operated legs · board outcomes
10-19AS476arrived−6
10-19AS489arrived+42
10-19AS571arrived−17
10-19AS592arrived+8
10-19DL3987arrived−1
10-19DL4031arrived−5
10-19DL4070arrived−5
10-19F92276arrived−23

Actual board outcomes rather than schedules, paired departure and arrival per flight and day.

Full board history, day by day →

Airports right now

live boards
SEASeattle +13 min smooth 🌤 scattered clouds · N 9 kt Full SEA delay board →
ONTOntario +0 min smooth 🌤 clear · N 3 kt Full ONT delay board →

Weather lens

Current conditions put the pressure at ONT: 40% odds of a 15+ minute delay and around +9 min expected when it bites, measured from this route's own weather-matched delay history. See live delays → · Weather risk by airport →

How the Seattle to Ontario route actually runs

Pro Flight Search records official board updates for nonstop SEA to ONT flights through the day: schedules, estimates, gate pushes and actual departures. The verdict above comes from operated flights, so it reflects what this route does rather than what the timetable promises.

Planning around a delay? Live airport delays · Weather delay risk map · Will a delayed flight be cancelled? · Do planes make up time in the air? · How we measure

Cite this data

Journalists, bloggers, and researchers may cite this page with attribution and a link to Pro Flight Search.

Suggested citation

Pro Flight Search — Seattle (SEA) to Ontario (ONT) route reliability, measured from operated flights on official airport boards.

Canonical URL
https://proflightsearch.com/search-flights/SEA-ONT
How we measure this →

SEA to ONT questions

Is SEA–ONT running on time right now?

Smooth skies ahead. The departure side at SEA is the weaker end, route health score 91/100. The airports section above carries the live status and delay window at both ends.

Morning or evening flight on SEA–ONT?

Operators schedule morning departures around 07:30 and evening departures around 19:56 from SEA. Earlier flights typically land before destination-airport delays accumulate later in the day; check the ONT delay card to confirm conditions when you'd arrive.

How long is the flight from SEA to ONT?

Great-circle distance is 1,540 km. With typical jet cruise speed plus taxi, climb and descent, expect roughly 139–162 min gate-to-gate on this route.

How often does SEA–ONT fly?

3 carriers operate this route, around 49 flights a week between them. Compare carrier days and times in the airline list above.