Appellate default consequences: discretionary dismissal or merits hearing; dismissal must be set aside on sufficient cause. Rule 42 empowers the Appellate Tribunal, when an appellant fails to appear at the scheduled or adjourned hearing, to either dismiss the appeal for default or hear and decide it on merits. If a dismissal for default has been made and the appellant later appears and shows sufficient cause for non-appearance, the Tribunal must set aside the dismissal and restore the appeal.