Section 6(3) in The University Grants Commission Act, 1956
(3)[ If a casual vacancy occurs in the office of the Chairman, whether by reason of his death, resignation or inability to discharge his functions owing to illness or other incapacity, the Vice-Chairman holding office as such for the time being shall, notwithstanding anything contained in sub-section (2) of section 5, act as the Chairman and shall, unless any other person is appointed earlier as the Chairman, hold the office of the Chairman for the remainder of the term of office of the person in whose place he is to so act:Provided that where no Vice-Chairman is holding office at the time when the vacancy in the office of the Chairman occurs, the Central Government shall, notwithstanding anything contained in sub-section (2) of section 5, appoint any other member to act as the Chairman and the person so appointed shall not hold the office of the Chairman for a period exceeding six months.
