What is the standard of review for a decision of the board of trustees to deny accidental disability benefits but to grant ordinary disability benefits?

Where, as in the present instance, however, the decision of the board of trustees to deny accidental disability benefits but to grant ordinary disability benefits is reached in [60 N.Y.2d 352] consequence of 6 to 6 tie votes, the standard of judicial review is necessarily different. There has been no factual determination by the board to be subjected to review under the normal substantial evidence standard. Rather, the disposition has been based on a procedural practice, first condoned in Matter of City of New York v. Schoeck, 294 N.Y. 559, 63 N.E.2d 104, supra and since 1945 observed, if not honored, by continuous use and general acceptance.