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Showing Delta only (incl. its regional partners)All airlines ×
1,076 nonstop flights · Aug 2025 – Jul 2026 · US DOT on-time records, all US airlines

No clear winner: Delta’s SEA → ONT flights land within a few points of 9 in 10 on time whatever the hour.

Best time to leave 8–9 am 93% arrive on time from SEA
Best single flight DL 4070 SEA 08:25 → ONT 11:17 · 89% on time Avoid DL 4031 SEA 14:35 → ONT 17:19 · 88% on time

Time of day × airport

Share of this route’s flights leaving within 15 minutes, by airport and scheduled departure hour, over Aug 2025 – Jul 2026. Blank: no flights then (or fewer than 40 in the year).

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SEA
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96
% of this route’s flights leaving within 15 min (small number: flights in the Jun 6 – Jul 31, 2026 schedule): 85+75–8465–7455–64under 55

Pick an hour to see this route’s flights leaving then.

Flights, best and worst

Flights in the Jun 6 – Jul 31, 2026 schedule that ran 150+ times in the year. Times are local. Pick a flight for its history.
DL 4070flown by SkyWest SEA 08:25 ONT 11:17 89%
DL 4031flown by SkyWest SEA 14:35 ONT 17:19 88%

All 4 Delta flights in the current schedule

Every flight that flew in the Jun 6 – Jul 31, 2026 schedule, with its record over Aug 2025 – Jul 2026. Times are local. Click a column to sort.
DL 4070flown by SkyWest SEA 08:25 ONT 11:17 2h 52m 151 89% 0.0% 87 min
DL 3840flown by SkyWest SEA 09:45 ONT 12:33 2h 48m 31 100% 0.0% –
DL 4031flown by SkyWest SEA 14:35 ONT 17:19 2h 44m 348 88% 0.3% 40 min
DL 3884flown by SkyWest SEA 19:50 ONT 22:41 2h 51m 86 84% 0.0% 33 min

Nonstops by airline and airport

Arriving within 15 minutes, Aug 2025 – Jul 2026. Pick a row to see that airline’s flights on that airport pair.
Delta SEA ONT 2h 48m 89% 0.4% 1,076 Flying now
Flying on a particular day? Pick a date above and the same ranking uses our forecast odds for each flight that day: Tomorrow.

About this data: US DOT on-time records, Aug 2025 – Jul 2026, all US airlines; regional flights count under the airline that sells them. Schedules (which flights and connections exist, and their times) are as of Jun 6 – Jul 31, 2026; seasonal flights outside that window aren’t ranked. Rebuilt monthly. JSON