. labor relations in the air transportation industry are regulated under the railway labor act ( rla ) , which vests in the national mediation board ( nmb ) certain functions with respect to disputes between airlines and labor unions relating to union representation and collective bargaining agreements ( cbas ) . when an rla cba becomes amendable , if either party to the agreement wishes to modify its terms , it must notify the other party in the manner prescribed under the rla and as agreed by the parties