Plain English Meaning

The line you see out the windshield where the ground (or sea) meets the sky. Pilots use this line as their main reference for keeping the airplane level and pointed the right way.

Full Definition

The visible line outside the aircraft where the earth's surface appears to meet the sky, used by the pilot as the primary visual reference for controlling the airplane's pitch and bank attitude in visual flight.

Context Anchor

Used in attitude flying when looking outside the airplane to control pitch and bank by reference to the real world, rather than by looking only at instruments.