AA 3978 then AS 421 at Denver
Phoenix Sky Harbor → Denver → Seattle
Timetable, Denver time
18:13AA 3978 from Phoenix Sky Harbor at the gate
18:37AS 421 to Seattle leaves the gate
24 min apart on the timetable
The last days
AA 3978 and AS 421 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.