THE VICTIM WAS OPERATING AN AERIAL BOOM TRUCK INSIDE THE BUCKET TO DISMANTLE A SHOP BUILDING. THE VICTIM & TWO OTHER EMPLOYEES WERE USING THE BOOM OF THE BUCKET TRUCK TO LIFT UP WOODEN 4X6 POST. THE POST WAS BURIED IN THE GROUND WITH CONCRETE. WHILE LIFTING THE POST, THE VICTIM WAS THROWN OUT OF THE BUCKET WHEN THE POST SUDDENLY RELEASED FROM THE GROUND.