AHM and TIC is not similar post. In the absence of HM , MC select a TIC from the teachers ( The selection may be on qualifications, seniority or efficiency). And he is the signatory person.You will find , from our superior authority,they write to the HM/ TIC/ SUPERINTENDENT.No where indicating the AHM.
AHM is not bound to do his duty as Teacher-in-Charge after resignation of H.M.
TIC is acted as head of the institution(HM).