  Atmospheric neutrino experiments can determine the neutrino mass hierarchy
for any value of $\delta_{CP}$. The Iron Calorimeter (ICAL) detector at the
India-based Neutrino Observatory can distinguish between the charged current
interactions of $\nu_\mu$ and $\bar{\nu}_\mu$ by determining the charge of the
produced muon. Hence it is particularly well suited to determine the hierarchy.
The hierarchy signature is more prominent in neutrinos with energy of a few GeV
and with pathlength of a few thousand kilometers, $\textit{i.e.}$ neutrinos
whose direction is not close to horizontal. We use adaptive neural networks to
identify such events with good efficiency and good purity. The hierarchy
sensitivity, calculated from these selected events, reaches a $3 \sigma$ level,
with a $\Delta \chi^2$ of 9.
