What terminal is Frontier Airlines at LGA? Frontier Airlines operates out of Terminal A at LaGuardia Airport (LGA), also known as the Marine Air Terminal. This terminal is smaller and less crowded, resulting in a more streamlined experience for Frontier travelers. It provides vital services such as baggage claim, check-in counters, and TSA security checkpoints, but has fewer shopping and food options than the larger terminals at LGA. LGA provides shuttles to other terminals, however customers should allow extra travel time due to the terminal’s more remote location inside the airport complex.