Admiral David L. McDonald Field (NRB/KNRB) is a military airfield located within Naval Station Mayport, situated on the north side of the St. Johns River near Jacksonville, Florida. The installation serves as one of the U.S. Navy's largest fleet concentration areas on the East Coast, supporting naval aviation operations, helicopter squadrons, and fleet logistics. The airfield primarily supports U.S. Navy and military aviation activities and is not open to commercial passenger traffic. It handles rotary-wing and fixed-wing military aircraft associated with the ships and commands based at Naval Station Mayport. The field is named in honor of Admiral David L. McDonald, a former Chief of Naval Operations. As a restricted military installation, civilian access is limited and the facility operates under the authority of the U.S. Navy.