A ROOF FALL OCCURED IN THE NO.1 LW""F"" PANEL HEADGATE ENTRY DURING RETREAT MINING OFF THE WEST MAINS. THE ROCKFALL WAS 33'LX15'HX21'W AT IT'S LARGEST POINTS. THE ROCKFALL STARTED AT THE TIPS OF THE SHIELDS & EXTENDED OUTBY FOR A DISTANCE OF 33' TO THE BACK OF THE LONGWALL CRUSHER. THE ENTRY WAS TWIN SEAM DEVELOPED & THE PRIMARY BOLTINGSYSTEM WAS 5/8 X4' CONVENTIONAL BOLTS. NO PERSON