On June 4, 2013, a Boeing 757-200 of Air China's new on the air about 20 minutes (other sources say 10 minutes) from Chengdu airport to Guangzhou purpose. At an altitude of 8,000 meters (28,000 feet), suddenly heard a loud noise. The pilot who does not know what is going on immediately contacted the air control tower to ask permission to go back to the Chengdu airport. When he reached the ground then seen if the giant plane nose was dented inward. Are UFOs involved in this incident?