Alaska AirlinesAS40% on time
Flights AS575 08:34 daily · AS571 12:31 daily · AS594 15:41 daily · AS489 20:31 Mo Th Fr Su
live
Direct flights from Seattle (SEA) to Ontario (ONT): 51 nonstop departures observed each week across 4 airlines. 47% of the last 19 tracked flights arrived within 15 minutes of schedule. The median arrival is 14 minutes late. 3 of the 19 tracked flights were cancelled. 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 15 November 2026 at 04:22 UTC.
Today, SEA → ONT
Sat 14 Nov · local times- 08:34 AS575Alaska Cancelled ·
- 12:31 AS571Alaska Departed Landed 15:55 +42
- 14:30 DL4031Delta Air Lines Departed Landed 17:04 −12
- 15:41 AS594Alaska Departed ONT est. 18:39 +22In the air · sched 18:17
- 20:11 DL3987Delta Air Lines Departed ·
Checked SEA board 20:22 · ONT board 17:26
SEA
Seattle
disrupted · +63
ONT
Ontario
smooth · +2
1,540 km · ~2h 28m est.
Runs rough · 4 airlines · 51x weekly · nonstop
47% on time
of the last 19 tracked SEA → ONT flights arrived within 15 minutes
Median arrival delay is +14 min. 3 of 19 tracked legs cancelled in the sample. Will a delayed flight be cancelled? →
Median arrival+14 minacross the last 16 arrivals
Flight time~2h 28mestimated from route distance
Weekly departures51x4 direct airlines on the leg
Cancelled15.8%recent route rate · 3 of 19
The week
scheduled departures · origin local time06121824
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Alaska AirlinesDelta Air LinesFrontier AirlinesSouthwest 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 daysHistory
operated legs · board outcomesActual board outcomes rather than schedules, paired departure and arrival per flight and day.
Full board history, day by day →
Airports right now
live boardsWeather lens
Conditions are tightest at ONT: a 37% chance of a 15+ minute delay. In this weather, the more delayed of the two airports is typically about +8 min. Both figures come from the two airports' delay records in similar weather. See live delays → · Weather risk by airport →
next sweep in 120s
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
How we measure this →
https://proflightsearch.com/search-flights/SEA-ONT
SEA to ONT questions
Is SEA–ONT running on time right now?
Some delays possible. The departure side at SEA is the weaker end, route health score 58/100. 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 07:45 and evening departures around 20:31 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?
4 carriers operate this route, around 51 flights a week between them. Compare carrier days and times in the airline list above.
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