(a) The Court may sit en banc to hear cases upon: (1) petition by a party filed in accordance with rules promulgated by the Supreme Court if the petition is granted by six judges of the Court; or (2) its own motion agreed to by six judges of the Court. (b) When the Court sits en banc, six of the judges constitute a quorum and a concurrence of six of the judges is necessary for a reversal of the judgment below. The Chief Judge shall preside, and in his absence the judge senior in service and present shall preside.