sptraveller - Following your own instinct may well end in court with you being charged with manslaughter, opening a door based on what you see may cause fire to enter the cabin and asphyxiate most of the pax. When the fire occurs at an airport the fire services are usually on site within minutes, as little as a minute and a half has been recorded. The captain will be in radio contact with the fire chief and the fire chief often has the best picture of all, certainly far better than you, the fire chief will advise the captain and that may well involve telling the captain not to order an evacuation as the fire can be stopped from outside. There was a case in Singapore last year when exactly that happened, all the pax disembarked down steps, uninjured, caused a riot of protest here on PPRuNe from a bunch of self interested Rambos who wanted to open the doors prematurely, fortunately none were on board the aircraft that was involved.