Biplane Hangar Safety Markings and Propeller Hazard Warning (1927)

An open-cockpit biplane inside a brightly lit hangar with the word DANGER stenciled in bold block letters near the propeller arc. — Biplane Hangar Safety Markings and Propeller Hazard Warning (1927) · Donald A. Hall Estate Collection

Documenting early airfield industrial safety standards, Donald A. Hall Sr. photographed this open-cockpit biplane resting inside a hangar with a prominent DANGER warning stenciled along the nose cowling. Painted directly adjacent to the propeller arc, the marking alerted ground crews and flight mechanics to stay clear of the spinning wooden blades, reflecting the era's evolving ground-safety protocols.