  We study the appearance of $\nu_{\tau}$ from active galactic nuclei (AGN)
through neutrino spin-flip. We consider two situations: i) Spin
(flavour)-precession in a reasonable strength of magnetic field in AGN,
$B_{AGN}$ ii) Adiabatically resonant conversions caused by an interplay of
$B_{AGN}$ and the violation of equivalence principle. Observational
consequences for both situations are discussed.
