Wondering What Terminal is Frontier Airlines at PHX? Frontier Airlines operates from Terminal 3 at Phoenix Sky Harbor International Airport. This terminal is meant to provide travelers with a seamless experience, with renovated facilities, modern waiting spaces, and easy access to gates. Terminal 3 is noted for its efficiency, shorter security lines, and easy navigation, making it a popular choice among Frontier customers. If you're flying with Frontier Airlines, proceed directly to Terminal 3 for check-in, boarding, and baggage services. Terminal 3 enhances your travel experience by providing comfortable seating areas as well as dining and shopping alternatives.