Plain English Meaning

Something tall or in the wrong place that planes could hit, so the FAA requires it to be lit, painted, or shown on charts so pilots can see and avoid it.

Full Definition

A formal designation applied to a structure, object, or condition that, due to its height, location, or characteristics, poses a risk to aircraft in flight and therefore requires marking, lighting, or charting to make pilots aware of it. The determination is made by the FAA following an aeronautical study, and the resulting requirements typically involve obstruction lighting, paint markings, and depiction on aeronautical charts.

Context Anchor

Seen in FAA discussions of aircraft lighting, obstruction lighting, and conditions that pilots must notice or avoid during flight.

Derivation

Hazardous comes from an older word for risk or chance. Aerial means related to the air. originally meant guiding a vessel from place to place; in it means guiding an aircraft. Together, the phrase points to a risk that affects aircraft as they move through the air.