Originally Posted by longtime lurker

Well, it IS a flight to Vegas. If a westbound flight to any U.S. city could work departing at 11PM, it would be Vegas.

The plane would have just remained overnight at MEM anyway. Instead, Frontier sends that plane (coming in from DEN) to Vegas (with plenty of time to become the early morning LAS-DEN run or do a 1AM turn to an eastern city), and another plane that would have just remained overnight in Vegas to MEM to be the morning MEM-DEN run. It makes some sense.