When a boarding bridge is genuinely dual-purpose, classification requires applying GRI 3 to determine essential character or principal use. CBP will examine design specifications, the buyer's intended installation, and whether the bridge meets aviation-specific or maritime-specific engineering standards. A binding ruling from CBP is advisable for ambiguous cases, as the two headings carry different duty treatment.

Retractable or telescoping gangways and enclosed walkways designed to connect a terminal building to a ship's passenger deck are the core commercial products under 8479790000. Fixed gangways or simple ramps that lack mechanical extension or elevation adjustment may classify differently depending on their construction and function. The mechanical, adjustable nature of the bridge is central to classification here.