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

No clear winner: United’s ONT → ORD flights land within a few points of 4 in 5 on time whatever the hour.

Nonstops (seasonal or thin)


United	ONT	ORD	4h 03m	81%	1.4%	291	Flying now

Best connections, any airlines

Most reliable Quickest (80%+ on time)

Ranked by chance you reach Chicago on time. Total trip = scheduled departure to arrival, layover included (Chicago is 2 h ahead of Ontario). Layovers up to 4 hours. Pick a connection for the details.


Southwest + Americantwo ticketsDetails →	ONT 05:30 → LAS 06:35WN 3150	3h 05m Las Vegas	LAS 09:40 → ORD 15:42AA 2020	8h 12m	100%	90%
Delta + Americantwo ticketsDetails →	ONT 17:59 → SEA 20:50DL 4031 · flown by SkyWest	3h 06m Seattle	SEA 23:56 → ORD 06:02 +1AA 2881	10h 03m	98%	90%
Alaska + Unitedtwo ticketsDetails →	ONT 17:32 → PDX 19:49AS 2456 · flown by Horizon	2h 51m Portland	PDX 22:40 → ORD 04:45 +1UA 2094	9h 13m	98%	87%
Southwest + Unitedtwo ticketsDetails →	ONT 21:40 → BWI 05:30WN 3143	2h 46m Baltimore	BWI 08:16 → ORD 09:30 +1UA 2749	9h 50m	100%	86%
Southwest + Americantwo ticketsDetails →	ONT 18:30 → SMF 19:55WN 3170	3h 15m Sacramento	SMF 23:10 → ORD 05:36 +1AA 3060	9h 03m	93%	86%
Delta Details →	ONT 22:00 → ATL 05:18DL 2892	2h 07m Atlanta	ATL 07:25 → ORD 08:35 +1DL 1178	8h 35m	100%	84%
United Details →	ONT 18:39 → SFO 20:07UA 5624 · flown by SkyWest	3h 23m San Francisco	SFO 23:30 → ORD 05:57 +1UA 368	9h 18m	100%	83%
Southwest + Americantwo ticketsDetails →	ONT 05:15 → PHX 06:30WN 864	2h 00m Phoenix	PHX 08:30 → ORD 14:21AA 319	7h 06m	98%	83%
Tight connection: often missed
United Details →	ONT 13:50 → SFO 15:15UA 1375	1h 06m San Francisco	SFO 16:21 → ORD 22:59UA 1482	7h 09m	62%	50%
American Details →	ONT 14:15 → DFW 19:30AA 2239	1h 30m Dallas-Fort Worth	DFW 21:00 → ORD 23:39AA 2346	7h 24m	71%	40%
American Details →	ONT 12:35 → DFW 17:50AA 2242	48m Dallas-Fort Worth	DFW 18:38 → ORD 21:22AA 1424	6h 47m	70%	26%

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

DEN · 1h 15m · leaves 05:00 3%

SEA · 1h 18m · leaves 06:20 6%

PHX · 1h 00m · leaves 06:11 8%

Afternoon and evening

SEA · 1h 03m · leaves 14:05 20%

DFW · 48m · leaves 12:35 30%

SFO · 1h 06m · leaves 13:50 38%

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.

The table above includes two-ticket connections (marked “two tickets”), held to the 90-minute minimum. One ticket only →

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