A second Navy anti-submarine helicopter went down in the West Sea, Saturday, less than a week after another Lynx chopper crashed in the same sea, leaving one dead and three others missing. All three crew members of the second Lynx were rescued after it made an emergency landing at around 10:13 p.m. in waters off the west coast. The British-made helicopter was on its way back to its 4,500-ton destroyer ``mother-ship'' after a patrol mission that involved identifying a mysterious object, which Navy officials said was found to have been a flock of birds.