A Russian-made airliner carrying 46 people lost contact with air traffic controllers in Indonesia during a demonstration flight Wednesday. The Sukhoi Superjet-100, which had Russian diplomats and potential buyers from Indonesian airlines on board, had taken off from Jakarta at 2 p.m., and radio contact with it was lost after it descended to 6,000 feet near Satak Mountain in West Java. It was supposed to return to Jakarta 50 minutes later. "It was veering a bit to one side, the engine roaring. It seemed to be heading toward Salak, but I didn't hear an explosion or anything," one man who lives near the mountain said. "A helicopter has just returned but says there is no trace of it," said somebody who had flown on the first flight. Officials said the airliner — the first completely new one designed in Russia since the Soviet Union fell — may have crashed or been hijacked but would be out of fuel by now.