After the flight landed at Honolulu, and following her arrival announcement, the stewardess observed smoke midway in the cabin and immediately informed the captain. The presence of smoke was confirmed and the captain immediately stopped the aircraft and notified the control tower that he had a fire aboard. The forward passenger door was opened and the passengers were ordered to deplane. Passengers and crewmembers descended to the taxiway by means of the air stairs . Airport firefighting equipment arrived on the scene within 2 minutes of notification and the fire was brought under control within 30 seconds of their arrival . Investigation showed that the cockpit and cabin interior, including seats, rugs, wall and overhead coverings, were severely damaged by fire and excessive heat. PROBABLE CAUSE: “An undetected electrical short within the left nickel-cadmium aircraft battery, which resulted in the absorption or an increasing amount of heat energy over an unknown period of time and progressed to a state of thermal runaway.”