A mudflat south of San Diego, adjacent to the Tijuana River estuary and separated from Mexico by a few miles of coastal scrubland, might seem an unlikely location for what would become known as the Helicopter Capital of the World. But Naval Outlying Landing Field Imperial Beach has occupied this terrain since 1917, when the Navy first recognized the value of flat, open coastal ground for flight operations. The field grew through World War II and the Cold War into the primary training facility for Navy helicopter pilots, accumulating a title it has worn for decades — and which is inscribed, without apparent irony, on signs visible from the highway.
The facility was established during World War I as a seaplane base, taking advantage of the shallow waters of the Tijuana River estuary for floatplane operations. The Navy's aviation infrastructure in San Diego was still in its earliest phases — NAS North Island had opened on Coronado only a few years earlier — and the Imperial Beach location provided additional coastal access for experimental and training operations. The field was named Ream Field in 1918 in honor of Army Major William Roy Ream, the first flying surgeon of the U.S. Army and the first flight surgeon killed in an aircraft accident. Through World War II, the facility trained pilots and supported antisubmarine patrol operations along the Pacific coast. The shift from fixed-wing to rotary-wing focus came in the Cold War period, when helicopter technology matured and naval requirements for anti-submarine warfare platforms multiplied.
The claim to the helicopter capital designation is rooted in the concentration of helicopter training and operations that NOLF Imperial Beach sustained through the Cold War. Anti-submarine warfare was a primary Navy mission during this period, and helicopters were central to it: able to dip sonar into the water, to deploy sonobuoys, to detect and track Soviet submarines in the approaches to American ports and fleet anchorages. Training helicopter aircrews for this mission required dedicated facilities, and NOLF Imperial Beach developed the infrastructure, the instructors, and the operational expertise that made it the West Coast's primary rotary-wing training center. At peak operations, the number of helicopter flights originating from the field in a given year justified the capital designation by any reasonable measure.
The Tijuana River National Estuarine Research Reserve surrounds much of NOLF Imperial Beach, creating an unusual juxtaposition of military aviation operations and one of the most ecologically significant coastal wetlands in California. The estuary supports dozens of species of shorebirds and migratory waterfowl, some of them rare or endangered, and serves as a critical link in the Pacific Flyway migration corridor. Military training operations and wildlife conservation share the same airspace and some of the same ground, a coexistence managed through agreements and operational constraints. The estuary also receives the outflow of the Tijuana River, which carries pollution originating in Tijuana's overwhelmed sewer system north across the border — a binational environmental problem that has affected beach closures in Imperial Beach for decades.
Naval Outlying Landing Field Imperial Beach continues to operate as part of Naval Base Coronado, supporting helicopter training and operations for West Coast fleet units. The field's runway and facilities are used primarily by Helicopter Maritime Strike Squadrons and Helicopter Sea Combat Squadrons stationed at NAS North Island, providing additional airspace and landing area when North Island's primary runways are congested. The 'Helicopter Capital of the World' designation remains, though the Cold War anti-submarine mission that originally defined the facility has evolved with the fleet it serves. From the air, NOLF Imperial Beach is visible as a compact airfield at the southern edge of San Diego's coastal development, with the estuary's winding channels on one side and the Pacific surf on the other.
Naval Outlying Landing Field Imperial Beach (KNRS / Ream Field) is located at approximately 32.57°N, 117.10°W, immediately north of the U.S.–Mexico border and adjacent to the Tijuana River Estuary. The field is within Naval Base Coronado restricted airspace. San Diego International Airport (KSAN) is approximately 17 km north. The Tijuana River estuary's winding channels and the proximity of the Mexican border make this location distinctive from altitude. Exercise caution regarding airspace boundaries near the international border.