Ode to the old wind cone!
The tetrahedron wind indicator, also referred to as a wind cone, is rather old technology has become increasingly rare in the United States. Sometimes, appearing in old class G airports, this wind indicator pays homage the early years of aviation.
This style of wind indicator confuses a lot of pilots progressing through flight training because it’s perceived almost entirely backward from that of its more common predecessor, the wind sock.
Take note of the photo displaying the windsock pointing in the opposite direction of the pointy side of the wind cone. That’s because the tetrahedron displays wind direction with the flat side of the object and not the point. Due to the shape of the tetrahedron, the wind indicator positions itself into the wind with the flat face on the downwind. This is entirely opposite of the wind sock.
Regardless, you won’t see many of these wind indicators out in the wild due to their confusing design and lack of ability to display approximate wind speed, and that they’re only allowed to be present at uncontrolled airports.
Yet, they are still very much prevalent on an FAA exam.
So we hope you’ll stay sharp and know one pointy side from the other!