What Terminal is Delta Airlines at DEN? If you're flying Delta Airlines through Denver International Airport (DEN), you'll be using Concourse A. Delta operates out of Terminal West, with check-in and baggage claim conveniently located there. Once you're checked in, the train will take you to Concourse A for your departure. Delta's service at DEN is smooth, with friendly staff and an easy boarding process. Whether you're heading to Atlanta, Salt Lake City, or beyond, Delta ensures a comfortable journey.