WN 2509 then UA 5421 at Denver
Omaha → Denver → Lubbock
Timetable, Denver time
14:15WN 2509 from Omaha at the gate
14:04UA 5421 to Lubbock leaves the gate
23 h 49 apart on the timetable, overnight
UA 5421 leaves 23 h 49 after WN 2509 arrives on the timetable: more than half a day, so not a connection we count.