Plain English Meaning
Something has gone wrong in the air that needs the pilot to act now. It covers anything from a serious problem like an engine failure (distress) to a worrying situation like getting low on fuel or being unsure of position (urgency).
Full Definition
A situation occurring during flight in which the safety of the aircraft or persons on board is threatened and which requires immediate action by the pilot. It includes any condition classified as either a distress (immediate assistance required) or urgency (concern about safety but not immediate assistance required) situation under FAA definitions.
Context Anchor
Seen in instrument flying when discussing , , and decisions made while flying without .