agreement. (5) Mediation If the parties have failed to reach an agreement before the date that is 90 days after the date on which bargaining is commenced under paragraph (4), or any later date agreed upon by both parties, either party may notify the Federal Mediation and Conciliation Service of the existence of a dispute and request mediation. Upon receiving such a request, the Director of the Federal Mediation and Conciliation Service shall promptly communicate with the parties and use best efforts, by mediation and conciliation, to bring them to agreement. (6) Arbitration (A) In general If the Federal Mediation and Conciliation Service is not able to bring the parties to agreement by mediation or conciliation before the date that is 30 days after the date on which a request for mediation is made under paragraph (5), or any later date agreed upon by both parties, the Service shall refer the dispute to a tripartite arbitration panel established in accordance with such regulations as may be prescribed by the Service. (B) Members A tripartite arbitration panel established under this paragraph with respect to a dispute shall be composed of 1 member selected by the labor organization, 1 member selected by the employer, and 1 neutral member mutually agreed to by the parties. The labor organization and employer shall each select the members of the tripartite arbitration panel within 14 days of the Service’s referral. Any member not so selected by such date shall be selected by the Service. (C) Dispute settlement A majority of a tripartite arbitration panel established under this paragraph with respect to a dispute shall render a decision settling the dispute as soon as practicable, and (absent extraordinary circumstances or by agreement or permission of the parties) not later than 120 days after the establishment of such panel. Such a decision shall be binding upon the parties for a period of 2 years, unless amended during such period by written consent of the parties. Such decision shall be based on— (i) the