U.S. shut down 19 of 24 land - based GPS - C navigation stations on Monday . GPS says Loran no longer works in place of Global Navigation System . They warn it is vulnerable to counter - attacks , suggest keeping Loran as backup .
U.S. shut down 19 of 24 land-based Loran-C navigation stations on Monday . Administration says Loran no longer needed in era of Global Positioning System . Critics warn GPS is vulnerable to cyber-attacks , suggest keeping Loran as backup .