(Updates with new signal paragraph 2, air search paragraph 12) By Ahmad Pathoni MAKASSAR, Indonesia, Jan 4 (Reuters) - Aircraft from Singapore on Thursday joined Indonesia's search for a plane that disappeared in bad weather with 102 people aboard four days ago, while navy vessels combed rough seas. First Air Marshal Eddy Suyanto, commander of the air base in Makassar, said a new report had been received that an emergency signal had been picked up south of Manado, the lost plane's scheduled destination in North Sulawesi province, three days ago. Until now, military and civilian aircraft have been mainly scouring the jungles and rugged mountains of western Sulawesi, while ships searched the Makassar Strait between the islands of Sulawesi and Borneo. Heavy rains and strong winds have hampered the search and the rough terrain has made communication and transport difficult. Government officials have apologised for erroneously saying on Tuesday that the 17-year-old Boeing 737-400, operated by budget carrier Adam Air, had been found and 12 people survived. The missing plane was carrying 96 passengers, including three Americans, and six crew. Portland's Oregonian newspaper identified the Americans as wood-products executive Scott Jackson, 54, and daughters Stephanie, 21, and Lindsey, 18. Two Singaporean Fokker-50s have joined Indonesian military aircraft in the search, while three ships are participating and another is on the way, Suyanto told Reuters earlier in the day. The United States also offered unspecified aid. The western Sulawesi search coverage is based on distress signals picked up by Singapore on Monday from the doomed plane. Ikhsan Tatang, director general of aviation at Indonesia's transport ministry, told Reuters the world's fourth most populous country lacked equipment to receive such signals from planes flying over its vast territory, which is as wide as the United States. "Not all countries need to have a special satellite to catch such signals. We don't need it because we have international cooperation," he said, adding Indonesia lacked money for that. RUGGED MOUNTAINS A Reuters photographer on one of the military planes said most of the aircraft circled over a rugged mountainous area in the Toraja highlands, a remote region popular with tourists. The confusion over the plane highlighted the logistical difficulties of dealing with disasters, from quakes and volcanoes to floods and forest fires, in an archipelago of 17,000 islands. President Susilo Bambang Yudhoyono has ordered a full investigation into the condition of all commercial planes in Indonesia and what went wrong in the Adam Air case, as well as an evaluation of the nation's transportation system. Adam Air's plane disappeared less than three days after a ferry capsized and sank off Indonesia's main island of Java. Officials say at least 239 of those on the ferry have been rescued since it sank overnight Friday, but nearly 400 more are unaccounted for. Twelve survivors who beached near an offshore rig, including a man who claimed to be the ferry's captain, were rescued on Wednesday, the Indonesian navy said. (With additional reporting by Heri Retnowati in SURABAYA, Mita Valina Liem, Muklis Ali and Muara Makarim in JAKARTA)
