  In models with substructure in the fermionic sector, excited fermion states
are expected. Excited leptons could be produced in the interaction of high
energy quasi-horizontal cosmic neutrinos with the atmosphere via neutral and
charged current processes, $\nu N \to \nu^* X$ and $\nu N \to \ell^* X$. The
hadronic component X, and possibly part of the excited lepton decay products,
would originate an extensive air shower, observable in large cosmic ray
experiments. In this paper, the sensitivity of present and planned very high
energy cosmic ray experiments to excited lepton production is estimated and
discussed.
