Without the express authorization of the commission after consultation with the director, and after a hearing, no certificate of public convenience or necessity issued to one (1) air carrier under the provisions of this act shall be combined, united, or consolidated with another such certificate issued to or possessed by another such carrier, so as to permit through service between any point or points served by the one (1) carrier on the one hand, and the point or points served by another such carrier, on the other hand.