Australia's Fortescue Metals Group Ltd will change its roster to increase the time workers spend at mines, as the world's fourth largest iron ore producer rushes to reduce costs in the face of plunging prices for the steelmaking ingredient. The change means workers employed in remote Outback mines will be flown out on charter planes once every two weeks rather than every eight days under a system known as 'fly in-fly out'. Off-duty time in each roster cycle will increase to one week from six days.