On 3 September 2010, a UPS Boeing 747-400 freighter flight crew became aware of a main deck cargo fire 22 minutes after take off from Dubai. An emergency was declared and an air turn back commenced but a rapid build up of smoke on the flight deck made it increasingly difficult to see on the flight deck and to control the aircraft. An unsuccessful attempt to land at Dubai was followed by complete loss of flight control authority due to fire damage and terrain impact followed. The fire was attributed to auto-ignition of undeclared Dangerous Goods originally loaded in Hong Kong.