@goldfish85
As you can well imagine, SR111 was discussed widely within the company at the time. If a FE might have helped, I don't know, possibly or maybe not. The situation was extremely tricky and misleading to the crew.
From where I sit and from what I did hear and read about this one from people who had direct access to the investigation, it became so dramatic because of a very unique sequence of events. I am going from memory here, long time, but what was discussed and what seemed to me the most logical chain of events was of a nature that was a "gotcha" from every angle one looked at it.
When they first smelled and later saw the smoke and took the decision to divert, they had no way of knowing the location and the mechanics of what went on. Initially, nothing big happened, and even worse, the smoke disappeared or lessened considerably, giving them the idea they had time to prepare the cabin, dump fuel and all that.
However, what went on behind this bulkhead was a trap truely set. The fire melted a cap fitted over an AC duct not used on the pax version of the MD11. Once the cap was gone, the duct sucked the smoke away from the flight deck. That is when the smoke disappeared. When they then went into the checklists and switched off the cabin bus, the fans which provided the suction stopped working and within very few moments, the fire started to move forward and attack the vital systems. A very short time later, they basically had nothing left and crashed.
Of course, the question arose what if they had not disactivated the cabin bus? Might it have bought them the time to go down and land? Very likely if they had gone straight into Halifax or even cricled. But, and that is the crux, they had NO WAY of knowing this and did the absolutely logical thing by depowering the cabin bus, as per checklist. They were right in their assumption that this fire was electrical, so powering down unessential equipment is perfectly sound and what they were trained to do. As to the duct, nobody knew or thought about it's effect once the silicon cap was gone and probably there would not have been an effect, had the fire only been slightly different. And obviously, nobody knows what would have happened if they had continued flying with the fans still on, probably the fire might have eventually burnt through the fuselage aft of the flight deck.
So what really killed them was the sequence of events of smoke on, smoke disappears, giving them the illusion of time available to prepare for landing, following their checklists and with that unknowingly aggravating the situation to beyond control. Nightmare for everyone of us who ever might have to sort out such a situation.
Had they gone by the principle of "he who hesitates survives" on the checklists and at the same time gotten it on the ground overweight and PDQ, they might have made it, or not. BUT had they done so and the fire had been slightly different in nature, this might have been the recipe for disaster right there.
So the posters here who say evaluating a fire is not done got more than one point. I rekcon all of us would rather take the "blame" of an unnecessary diversion due to a faulty indication or cremated crewmeal than to ever ever get into a situation like the crew of Swissair 111 or UPS 6.