Frontier Airlines (F9) is a Denver-based ultra low-cost-carrier. Frontier Airlines states: "We currently serve more than 100 cities in the United States, Mexico, Canada, Puerto Rico and the Dominican Republic. We are the proud recipient of the Federal Aviation Administration’s 2015 Diamond Award for maintenance excellence, and we were recently named the industry’s most fuel-efficient airline by The International Council on Clean Transportation (ICCT) as a result of superior technology and operational efficiency. We believe travel should be for everyone and we are committed to delivering ‘Low Fares Done Right’. This is more than a tagline. It’s our driving philosophy."