166As the Commission has rightly demonstrated (see paragraph 155 et seq. above), the main barrier to entry in the air transport sector is the lack of available slots at the large airports. Consequently, it is necessary to determine whether the Commission erred in finding that, in the present case, the divestiture of slots provided for in the commitments package could be an effective way to restore effective competition. In that context it is for the applicant to adduce evidence that the divestiture of slots as provided for by the commitments was not sufficient to remedy the competition problems raised.