Plain English Meaning
Actively looking outside the cockpit and using available tools to spot other aircraft or obstacles early enough to stay clear of them.
Full Definition
The pilot's ongoing responsibility to see other aircraft, terrain, and obstacles in time to take action that prevents a collision. In visual conditions, this is accomplished primarily through systematic outside scanning, supplemented by traffic advisories, onboard traffic displays, and standard right-of-way procedures.
Context Anchor
You encounter this during preflight planning, taxi, , , , , , and any time you are scanning outside the for traffic or .