Frontier Airlines Booking Not only is Low Fares Done Right the airline's motto, but Frontier is actually a low-cost airline that got its start in the aviation industry about 25 years ago. And still getting stronger. Flights to more than 100 cities in Mexico, Canada, the United States, Puerto Rico and more than 1,000 connecting routes testify to the airline's extensive network. Headquartered in Denver, Colorado, Frontier's primary hub is the Denver International Airport. With a fleet of 94 aircraft and 3,000 meticulous professionals, the airline is proud to be the eighth largest commercial airline in the United States. You must book Frontier Airlines tickets to experience the best flight. Passengers may take one piece of carry-on baggage and one piece of personal effects into the aircraft cabin as carry-on baggage. However, both items of baggage must meet weight and size restrictions. Carry-on baggage must be less than 24 x 16 x 10 inches, including wheels, handles, and belts. Also, it weighs no more than 35 pounds. In the case of a personal item, its dimensions must not exceed 8 x 18 x 14 inches and it must fit under the seat. For checked baggage, each bag must weigh less than 50 pounds and linear dimensions must not exceed 62 inches.