law: The Major Port Authorities Act, 2021
  10. Filling of casual vacancies.-
  Any vacancy occurring in the office of the Chairperson, Deputy Chairperson or any other Member whether by reason of his death, resignation or inability to discharge his functions owing to illness or other incapacity, shall be filled by the Central Government by making a fresh appointment within a period of three months from the date on which such vacancy occurs and the Member so appointed shall hold office for the remainder of the term of office of the person in whose place he is so appointed.