i had just watched the documentary on the canadian dc-9 that landed in Cincy with smoke in the cabin (with subsequent fireball on the ground) yesterday....which took me back to the several smoke in the tube scenerios in the mighty orion....

smoke in the tube is nothing to mess around with...immediate emergency if the source is unknown IMO. If I cant pull a breaker to make it stop within a couple minutes of smelling smoke...we are done!