Dated 15 July 1971, this schematic diagram maps the tactical instrument approach structure into Da Nang Air Base, showing four holding 'gates' - West, North, East, and South - along with planned radar vector routes and an alternate 'Lost Comm' route to be flown if radio contact was lost. Diagrams like this guided F-4 Phantom pilots safely back to base through Vietnam's often poor weather and heavy air traffic, translating complex airspace geometry into a clear, memorizable picture. Project: 218454