Passenger pontification and pilot safety

[AN2 Driver]

Originally Posted by Redgoblin

This must take time, during which the aircraft could be plummeting out of the sky. I’ve seen a documentary on a Canadian airline which dropped out of the sky (Fire on the Netherrealm) and the captain did everything by the book, so much so that he might have prevented disaster if he didn’t go by the book.
I understand that the accident was due to the wiring in the entertainment computer/ and the use of the foil in the wiring ducts, and also they never shut the server off, but even so was the pilot to blame… I would say no quite frankly he followed protocol.

I wonder which documentation you have seen. There was an excellent one by a Canadian and a Swiss aviation reporter, one of the best pieces of aviation journalism made documentation I have ever seen, there was another one by the BBC I think which was also not bad but missed the points I am making below. However, you have gotten several things wrong.

The flight in question was an MD11 operated by Swissair. They developed a "smell" in the cockpit while cruising at 33000 ft after departure from New York Kennedy. That smell came and went, was very difficult to determine. So they decided to land at Halifax. During the descent, they went through the checklists for "Smoke of unknown origin" when the situation very rapidly and seriously deteriorated. At the end, they lost ALL their instrumentation and finally lost control of the aircraft which then crashed into the sea.

The subsequent inquiry brought forth a sequence of events that is, by its very nature, not covered by any book or checklist. The account I do here is by memory so I might simplyfy things a bit, but it brings forth the essence of the accident. An electric wire had produced a short circuit in such a way that the circuit breakers involved did not trip. A small fire developed behind the cockpit bulkhead, which was the "smell" they felt when they made their decision to descend and land. The smoke/smell then disappeared again, making them believe that whatever the situation was, it had either stopped or at least subsided. Reason for that was a silicon cap over an air conditioning duct which usually blocks this tube (which is not used in the passenger version of the MD11) and which melted during the initial fire. Once that cap had gone, smoke and heat was sucked backwards into this duct, thereby diminishing the effects in the cockpit and preventing damage to happen there. The suction in this duct came from recirculation fans in the cabin.
In the course of the "Smoke of unknown origin" procedure, electrics should (understandably so) be reduced to a bare minimum in order to stop the ignition source of any possible electrical fire. This involved switching the cabin bus off, which powers amongst other things the "server" you refer to and also the recirculation fans. The result of this was catastrophic: Rather than being drawn away from the electronics within the cockpit, the fire (which had become self sustained at the time) now spread rapidly into the cockpit area (overhead and rear bulkhead), destroying most of the electrical system, thereby blanking out the screens, causing all sorts of warnings e.t.c. In the end, the fire damage was so great that the plane became uncontrollable (as it was night and they were in IMC), so they lost control and crashed.

Could they have made it, if they had simply planted it down without any checklists done and overweight? The experts are fighting about that one, I personally think speed was not even the primary issue. The moment the cabin bus was switched off, the crash was no longer avoidable. Clearly, leaving them on would have at the very best bought them time, but in the end time is what they ran out of. But that crew had absolutely NO WAY of knowing this, had nothing to go by, because nobody had ever contemplated such a succession of events. If ever a crash resulted out of a "loose - loose" situation, this is the one I know about.

Even the report did not put that much emphasis on that sequence of events, which is why some books and docus about this accident missed it altogether. Of course, for the prevention of future accidents, the ignition source and the fact that the insulation blankets were flammable under certain conditions were much more important and therefore were naturally put at the top of the list, maybe also because the exact sequence of these events is very hard to prevent once the fire is started. What has come out clearly tough is the necessity to get a fire on the ground ASAP, even on suspicion.

Best regards
AN2 Driver

[Redgoblin]

Thanks to all your responses

Yes it was the Swissair flight 111 in 1998, sorry for the confusion.

The program I saw was from the series on National Geographic TV channel - ‘Air Disasters’.

But still, the captain appeared to have done the right thing, in line with his company procedures and dumped the fuel in order to land safely. It’s probably fruitless for me to say this, but could he have landed heavy, the program highlighted the fact he was strictly by the book, what would you have done in this situation?

The ATC guy also felt guilty afterwards even though he was just following orders, and was also in my opinion just doing his job. Given the fact he didn’t know the situation was getting worse he had no concern to let them land heavy.

Also

I remember the program mentioned at the end that the foil material - Metallized Polyethylene Terephthylene (MPET) in the ducts could be dangerous to civil aviation and some sort of ruling in the industry meant that airlines should replace this material.

Does anyone know what materials are used now, and if so how safe are they?

Does it really even matter…I mean if something is going to burn it will right.

So I was thinking…
Why don’t airlines use Fiber cables instead of copper – or do they nowadays?

No Electromagnetic Interference (EMI) issues
No Radio Frequency Interference (RFI) issues
Lightweight
Smaller diameter
Greater bandwidth
No grounding or shorting concerns
Upgradeable without ripping out & replacing cable harnesses
Can withstand more tension than copper (even though made fiber is made from glass)

[AN2 Driver]

Originally Posted by Redgoblin

Thanks to all your responses
Yes it was the Swissair flight 111 in 1998, sorry for the confusion.
The program I saw was from the series on National Geographic TV channel - ‘Air Disasters’.
But still, the captain appeared to have done the right thing, in line with his company procedures and dumped the fuel in order to land safely. It’s probably fruitless for me to say this, but could he have landed heavy, the program highlighted the fact he was strictly by the book, what would you have done in this situation?
The ATC guy also felt guilty afterwards even though he was just following orders, and was also in my opinion just doing his job. Given the fact he didn’t know the situation was getting worse he had no concern to let them land heavy.

The crew acted according to procedures and in my opinion they had not much of a choice. Up until the situation escalated, they had no indication of serious trouble, so they followed the procedures. When the situation did escalate indeed, it happened at a very fast rate which then left them with nothing.

If they had known what we know now, certainly they would have landed heavy (or at least tried to) and certainly not switched the cabin bus off. But they did not, in the opposite, the whole situation was so absurd that they had no CHANCE of even guessing the right thing to do. That is what I meant. There are situations in which the procs won't help you, they might even make a manageable situation worse.