(a)the authorities by which any of the powers conferred by or under this Act are to be exercised;(aa)[ the regulation of air transport services, and the prohibition of the use of aircraft in such services except under the authority of and in accordance with a license authorising the establishment of the service; [Inserted by Act 5 of 1944, Section 2 (w.e.f. 7.3.1944). ](ab)[ the economic regulation of civil aviation and air transport services, including the approval, disapproval [or revision on tariff of operators of air transport services other than the tariff referred to in clause (a) of sub-section (1) of section 13 of the Airports Economic Regulatory Authority of India Act, 2008]; the officers or authorities who may exercise powers in this behalf; the procedure to be followed, and the factors to be taken into account by such officers or authorities; appeals to the Central Government against orders of such officers or authorities and all other matters connected with such tariff.