Definition
During a crosswind landing, the main landing gear wheel on the side of the airplane that the wind is blowing from. In a properly executed crosswind touchdown, this wheel contacts the runway first while aileron is held into the wind, before the downwind main wheel and finally the nosewheel settle onto the surface.
Plain English
The main wheel on the side the wind is coming from. In a crosswind landing, it's the wheel that touches the runway first.
Context Anchor
Encountered when learning crosswind landings, especially the touchdown step where one main wheel may touch before the other.
Derivation
Upwind' means toward the direction the wind is coming from — into the wind. So the upwind main wheel is simply the main wheel on the into-the-wind side of the airplane.
Why Pilots Care
Touching the upwind main wheel first maintains directional control and keeps the airplane from weathervaning or drifting off the runway in a crosswind.
Grounding Statement
Picture a left crosswind: the pilot lowers the left wing slightly, and the left main wheel becomes the upwind main wheel that touches first.
Intuition Check
Upwind does not mean the direction the airplane is traveling; it means the side the wind is coming from. Main wheel does not mean “most important wheel” in a general sense; it means one of the primary landing wheels that support the airplane on the ground.
Example Sentence 1
As the airplane settled through the flare, the upwind main wheel touched down first, followed smoothly by the downwind main and then the nosewheel.
Example Sentence 2
After the upwind main wheel contacted the runway, the pilot lowered the other main wheel and then the nosewheel.