This is only achieveable AFTER completing the "No one leaves alive" Achievement/Easter Egg on Mob of the Dead. Simply build the airplane to fly/escape Alcatraz and earn the 75GS No One Leaves Alive achievement. You need to complete either the CURRENT or next round to reveal the electric chairs. Press "x" and respawn/get killed and reappear in Alcatraz, thus starting "The Rounds". Upon arriving you must finish either the current or next round to both reset the plane (its already built so no worries about parts again) and the fuel cans to fly to the Golden Gate Bridge again. The gas cans/fuel are located near/the exact location of the plane parts, again five (5) are needed to fly. Simply repeat three (3) times and it will appear once back in Alcatraz your forth (4th) time.