Frontier uses a zone boarding system, and passengers should pay close attention to announcements. Boarding typically starts 30–40 minutes before departure and closes 15 minutes before the flight. If your flight departs from one of the ground gates: Be prepared to walk down stairs to the tarmac Follow clear signs and crew instructions Use both the front and rear doors when ... https://airportsterminalhub.com/airlines/frontier-airlines/frontier-airlines-den-terminal-denver-international-airport/