In aviation, an outside check or walk around is the air crew inspecting certain elements of an aircraft prior to boarding for security, safety, and operational reasons.
The pilot primarily inspects outside parts of the aircraft they will steer, e.g. control surfaces, tires and possible leaks from fuel or oil.
The preflight inspection is a thorough and systematic means by which a pilot determines if an aircraft is airworthy and in condition for safe operation. POHs and owner/information manuals contain a section devoted to a systematic method of performing a preflight inspection.[1]