US experts have arrived on Indonesia's Sulawesi island to help investigate the apparent crash of a jetliner that disappeared with 102 people on board after battling fierce winds and storms. The pilot did not issue a mayday before dropping off the radar near the coastal town of Majene, and there has been no emergency location signal to guide thousands of searchers in the island's dense jungles and surrounding seas. By nightfall Saturday, after a fifth day of searching, there was still no trace of the Indonesian budget carrier Adam Air's Boeing 737. "It's impossible that it just disappeared," Indonesia's Vice President Jusuf Kalla said after meeting with search officials and families of the passengers of Flight KI-574. "Even if it takes a month ... we have to keep searching," Kalla said.