One-way operators are proposed for modeling wide-angle wave propagation in 3D heterogeneous, transversely isotropic media with a vertically symmetric axis (VTI). The operators are built in the wavenumber-space domain such that the terms in the space domain and in the wavenumber domain are separable. This means that the resulting algorithm can be implemented alternately in the space and wavenumber domains using the fast Fourier transforms. The proposed one-way operators can accommodate a wide range of anisotropy rather than the weak anisotropy. An optimization scheme is used to determine the coefficients in the operators by directly matching to spatially varying, exact anisotropic phase-shift operators over a prescribed angular range of wave propagation. We demonstrate the accuracy of the one-way operators by a comparison with the two-way elastic anisotropic finite-difference modeling in the presence of severe lateral variations.