A sightseeing helicopter with a family of four and the pilot on board was headed back to Honolulu after touring Waimea on Thursday morning when it crashed into waters just off the Arizona Memorial visitors center, to the disbelief of scores of bystanders.A 15-year-old passenger in the chopper was in critical condition following the crash; he was taken to the Pali Momi Medical Center. Two others on the chopper, a 50-year-old man and a 45-year-old woman, were in stable condition at Pali Momi.