Actually, I’m yet not seen in manual regarding this matter, but the normal procedure is-
M.C can select the TIC acc. to seniority and suitability starting from AHM (where AHM is exist), if AHM is unwilling then senior most teacher then acc. to seniority. But if everybody is deny to accept the responsibility of TIC, then AHM (or, Top most senior Teacher where, there is no AHM post) is bound to take this responsibility.