AN UNINTENTIONAL ROOF FALL OCCURRED AT THE 29+30 X-CUT OF ENTRY #2 IN THE 3RD NORTH PANEL. THE FALL MEASURED 40' LONG X 19' WIDE X 5' THICK. NO ONE WAS INJURED & VENTILATION AND/OR PASSAGE OF MEN WAS NOT AFFECTED. THE FALL WAS CAUSED BY A HIDDEN SLIP.