Tilt angles as a function of Galactic height for different positions across the Galaxy. We show the trends with z for R = [5, 7, 9, 11] kpc. The red squares, green diamonds, and blue crosses are based on the methods described in Sect. 3.2 (see text). The solid black line shows the trend that would correspond to spherical alignment. The tilt angle is changing from spherical alignment in the inner Galaxy (R ∼ 5 kpc) towards shallower tilt angles at R ∼ 11 kpc. The cyan line shows the analytic description of the data as proposed in Sect. 4.4.