What size lettering is required for the "Keep off this elevator when in operation" warning placard?

The correct answer is based on the established safety standards that dictate the size of lettering for warning placards used in environments where safety is paramount, such as aboard aircraft carriers. A 2-inch lettering size for the "Keep off this elevator when in operation" warning placard ensures visibility and readability from a reasonable distance. This is particularly crucial in a shipboard environment where operational areas may have heightened noise levels or limited visibility, making it essential for safety messages to stand out to prevent accidents.

Choosing the appropriate letter size aligns with regulatory guidance and best practices to ensure that personnel can clearly understand and follow safety instructions without hesitation. A 2-inch size strikes a balance between being large enough to attract attention while still being practical for use in confined spaces typical on ships.