AC 4121 then AF 2708 at San Francisco
Ontario → San Francisco → New York JFK
Timetable, San Francisco time
17:50AC 4121 from Ontario at the gate
11:50AF 2708 to New York JFK leaves the gate
18 h apart on the timetable, overnight
AF 2708 leaves 18 h after AC 4121 arrives on the timetable: more than half a day, so not a connection we count.