On 1 November 2011, a Boeing 767-300 landed at Warsaw with its landing gear retracted after declaring an emergency in anticipation of the possible consequences which in this event included an engine fire and a full but successful emergency evacuation. The Investigation attributed inability to achieve successful gear extension using either alternate system or free fall to crew failure to notice that the Battery Busbar CB which controlled power to the uplock release mechanism was tripped. Gear extension using the normal system had been precluded in advance by a partial hydraulic system failure soon after takeoff from New York.