Itineraries flown on 20+ days in the Jun 6 – Jul 31, 2026 schedule · each leg’s record Aug 2025 – Jul 2026

No clear winner: airlines and hours on this route all land within a few points of 83% on time.

Nonstops


Delta	SEA	ONT	2h 48m	89%	0.4%	1,076	Flying now
Frontier	SEA	ONT	2h 46m	84%	1.8%	169	Flying now
Alaska	SEA	ONT	2h 41m	78%	1.5%	1,259	Flying now

Best connections, one ticket

Most reliable Quickest (80%+ on time)

Ranked by chance you reach Ontario on time. Total trip = scheduled departure to arrival, layover included. Layovers up to 4 hours. Pick a connection for the details.


Southwest Details →	SEA 06:15 → OAK 08:25WN 266	2h 25m Oakland	OAK 10:50 → ONT 12:10WN 3062	5h 55m	100%	96%
Southwest Details →	SEA 05:00 → SMF 06:50WN 3629	2h 20m Sacramento	SMF 09:10 → ONT 10:30WN 3805	5h 30m	100%	92%
Alaska Details →	SEA 10:14 → PDX 11:21AS 3090 · flown by SkyWest	3h 09m Portland	PDX 14:30 → ONT 16:52AS 2093 · flown by Horizon	6h 38m	100%	90%
Delta Details →	SEA 05:30 → SLC 08:30DL 1128	2h 49m Salt Lake City	SLC 11:19 → ONT 12:10DL 3172	6h 40m	99%	89%
United Details →	SEA 05:00 → DEN 08:43UA 2601	2h 42m Denver	DEN 11:25 → ONT 12:47UA 430	7h 47m	99%	87%
Delta Details →	SEA 09:30 → SLC 12:38DL 1016	3h 07m Salt Lake City	SLC 15:45 → ONT 16:41DL 4443 · flown by SkyWest	7h 11m	99%	86%
Southwest Details →	SEA 06:45 → SJC 08:55WN 3626	1h 55m San Jose	SJC 10:50 → ONT 12:05WN 3151	5h 20m	97%	83%
Delta Details →	SEA 17:59 → SLC 21:09DL 1165	1h 50m Salt Lake City	SLC 22:59 → ONT 23:48DL 1614	5h 49m	94%	82%
Tight connection: often missed
United Details →	SEA 14:33 → DEN 18:22UA 333	58m Denver	DEN 19:20 → ONT 20:42UA 2028	6h 09m	63%	47%
United Details →	SEA 07:00 → SFO 09:18UA 1578	1h 22m San Francisco	SFO 10:40 → ONT 12:12UA 2661	5h 12m	55%	43%
American Details →	SEA 11:40 → DFW 17:50AA 767	1h 00m Dallas-Fort Worth	DFW 18:50 → ONT 19:59AA 2236	8h 19m	68%	40%

Same layover, different day-part

How often the first flight arrives too late to connect (45 min minimum), for one-ticket layovers of 45–80 minutes.

Morning

DFW · 1h 18m · leaves 05:05 4%

SLC · 56m · leaves 07:15 5%

Afternoon and evening

PDX · 1h 13m · leaves 19:22 15%

DFW · 1h 00m · leaves 11:40 32%

Delays build through the day, so an afternoon first leg eats the layover. A short connection is fine early in the morning and a gamble later on.

Mixing airlines

One ticketMiss it and the airline rebooks you; bags go through. 45 min is enough.

Separate ticketsMiss it and you buy a new ticket. Re-check bags, clear security again: we require 90 min.


Delta DL 3818 SEA 09:30 → PDX Alaska AS 2093 PDX 14:30 → ONT Connection details →	3h 51m	7h 22m	100%	91%
Alaska AS 360 SEA 08:48 → SLC Delta DL 4443 SLC 15:45 → ONT Connection details →	3h 50m	7h 53m	100%	87%
Alaska AS 373 SEA 16:47 → SLC Delta DL 1614 SLC 22:59 → ONT Connection details →	3h 09m	7h 01m	98%	87%

Rank all connections, any airlines →

Regional partners count as the airline that sells them: SkyWest flying Delta Connection is one Delta ticket.

How these are worked out. Makes the connection: share of the last year’s flights where the first flight arrived with at least 45 minutes to spare (90 on separate tickets). Arrives on time: first flight not cancelled × connection made × second flight not cancelled and arriving within 15 minutes. Not yet counted: the second flight also leaving late (which helps), gate-to-gate distance at the hub, and rebooking after a missed connection.

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