What terminal is Frontier Airlines at SJU? Frontier Airlines operates from Terminal A at Luis Muñoz Marín International Airport (SJU), the main gateway to Puerto Rico. This terminal provides a smooth and budget-friendly travel experience for passengers flying to and from various destinations across the United States. Terminal A is equipped with essential amenities such as check-in cou... https://airlineofficedetails.com/frontier-airlines-san-juan-airport-terminal-sju/