Plain English Meaning

The parts of the turn where the nose is pointed into the wind. The plane is flying against the wind during these portions, so it moves more slowly across the ground.

Full Definition

Aircraft headings that point into the wind. During a steep spiral, these are the portions of each turn where the airplane is flying against the wind, which produces the slowest groundspeed and the tightest ground track relative to the reference point.

Context Anchor

Used in steep spirals and other ground-reference maneuvers when correcting the turn for wind.

Derivation

Upwind' simply means 'toward the source of the wind' — the direction the wind is coming from. A is the direction the airplane's nose is pointed. So an upwind heading is one where the nose is pointed into the oncoming wind.