TractAngle[tracts]

calculates the angle of each tract segment with the z-plane.

TractAngle[tracts,v₁]

calculates the angle of each tract segment with the plane normal to v1.

TractAngle[tracts,{v₁,v₂}]

calculates the elevation and azimuth angle of each tract segment with the plane normal to v1 and the azimuth angle in that plane relative to v2.