When the H.M is absent from school for his school purpose or takes leave then A.H.M is responded to run the school. But where there is no A.H.M., then the staff council,H.M. and M.C will select to a senior most teacher to act /to take decision when an emergency case arises. It may be rotation- wise for a year or so on ,where there is more then one senior most teachers.
Thanks a lot.