Swissair report fails to pinpoint 
cause of crash

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Halifax After the most expensive and exhaustive air-crash probe in Canadian history, investigators have failed to pinpoint the cause of a fire aboard Swissair Flight 111 that crashed off Peggys Cove, N.S., in 1999, killing all 229 people on board.

Although a probable source of the first electrical fault lies in the improperly installed entertainment and gambling system that the now-defunct Swissair used to pamper its highest-paying passengers in First and Business Class, investigators from the Transportation Safety Board acknowledge that they cannot be certain. And, they add, it is "unlikely, ... that this entertainment power-system supply wire was the only wire in the lead arcing event."

They insist, however, that the investigation has already advanced aviation safety, notably by identifying flammable materials such as acoustic insulation blankets that, once ignited, fuelled and spread the fire above the cockpit ceiling, eventually triggering a rapid series of failures that left the aircraft in desperate straits in the dark off the Nova Scotia coast.

"Without the presence of [the insulation] and other flammable material, this accident would not have happened," said Vic Gerden, lead investigator into the worst-ever aviation disaster over Canadian territory.

Although the New York-to-Geneva flight was close to the major airport at Halifax when the pilots first noticed smoke, they initially elected to divert to Boston where Swissair had a ground base capable of handling inconvenienced passengers.

Ever since the crash, speculations has swirled as to whether the pilots had time to make an emergency descent and landing at the long Halifax airport almost directly ahead of them and only a few minutes flying time away.

"Theoretical calculations showed that the very earliest they could have landed was at 10:27 p.m.," four minutes before the MD-11 actually slammed into the sea, Mr. Gerden said. He also said, however, that because of the rapid and sequential failures of electrical and other system from about 10:25 p.m. as the pilots struggled to fly the jet manually in the dark, "we have concluded ... They would not have been able to complete a safe landing in Halifax."

from this link

Report clears pilots in Swissair crash
Last Updated Thu, 27 Mar 2003 11:31:18

HALIFAX - The 229 people on board Swissair Flight 111 were doomed as soon as fire began in the jet's cockpit, according to the final report into the accident.

"Even if the pilots could have foreseen the eventual deterioration due to the fire, because of the rapid progression of the fire they would not have been able to complete a safe landing in Halifax," said Vic Gerden, the lead investigator for the Transportation Safety Board.

The TSB released its final report and a list of recommendations in Halifax Thursday.

Investigators have spent four and a half years and $57 million looking into the crash off Peggy's Cove on Sept. 2, 1998.

They say the fire started in a hidden area in the ceiling on the right side of the cockpit.


Vic Gerden displays insulation

Investigators concluded that a spark in the wiring of the in-flight entertainment system probably started the fire that led to the crash. The sparks ignited metallized plastic sheets covering thermal-acoustic insulation blankets in the area.

"It is important to emphasize here that without the presence of this and other flammable material, this accident would not have happened," Gerden says.

The report says the crew didn't know about the fire until it was too late.

The TSB has issued 23 safety recommendations, including nine new ones on Thursday. Among them:


  • reduce the risk associated with the use of insulation covered with metallized plastic
  • develop more rigorous flammability testing for all materials
  • prevent the use of any materials that help fires start or continue burning

The 330-page report brings to an end the largest and most complex air crash investigation in Canada's history.

from this link


Comment:  Based on the Multimedia WebCast only

No big surprises there on cause or development of the fire (or the reason for the ultimate loss of control). Obvious reluctance to come to any conclusions about anything incriminatory but the MPET blankets. You can clearly see the outcome of arcing events upon a large wiring bundle (in the photo that supposedly shows where the initiating event occurred). At this stage I am still unclear on what side of the bulkhead that arc event occurred. I assume the cockpit side, crown area (and somewhere just after all those wires (in that huge bundle) exit the bulkhead throughway). The question of collecting together large numbers of wires and transiting them through one vulnerable throughway should get a mention in the Report. It does in FAR25.


A. Kapton and ETFE and other wiring insulations:  => should be tested and evaluated (same old story). Totally unprepared to say anything more than that a wire arced and that it was associated with the IFEN (one or two wires)


B.  EVAS =>  should get a big boost (but nothing said about whether or not it might have changed the outcome).

The Cockpit Fire started in a large wire-bundle in the circled position shown above


C.  IFEN =>  criticisms of its build standard, certification and electrical interface but not a lot there for the lawyers to hang their hats upon. Equivocation only, no incrimination. The FAA has neatly side-stepped any accusation of negligence by the TSB assertion that by the time a Cabin-Bus connected IFEN had been switched OFF, the fire would have been very much underway (so the fact that it wasn't correctly on the cabin bus is "just a detail"). There's a certain fault of logic in that approach.


D.   MD-11 =>  no criticism of the S/E/A or any aspects of this aircraft but mention of the 50+ AD/s that were required to justify it keeping its airworthiness certificate. Vague mention of amending checklists and endorsement of the panacea omnibus solution of landing ASAP.


E.   Electrical fire detection and fire-fighting  => In response to journalist's question about the lack of "behind the linings" fire detection and suppression, Gerden launched off on a red herring about cargo holds (to be expected - but in actuality an entirely different problem). However the TSB has made "recommendations".


F.   Pilots blameworthiness (or otherwise) =>  all conclusions were in favour of the pilots. They were "suckered in" and they COULD NOT have safely landed anyway. But they were doing their best. Fails to address training and adequacy of checklists - but that may be in the report.


G.   Third Crew Man /FE  =>  no mention at all of the pilots' overload situation or the great safety utility of having a third man.... particularly with locked cockpit doors, trapped in seat on umbilical oxy - and loss of cabin intercom.


H.   Part that aircon and venting played  =>  Journos were getting the two mixed up. Aircon sucked the pilots in initially but the vents were sucking and evacuating smoke and it was only when the cabin exhaust fans were switched off that the smoke was drawn forward and the fire able to develop more strongly in a forward direction - and into the flight-deck ceiling. Their assertion that the flight-deck ceiling "sagged" and alarmed the pilots into declaring an emergency must have been based upon what they physically found.


I.   MPET  =>  the real villain (according to the TSB). Supposedly without the MPET blankets there wouldn't have been an accident (but that's not necessarily the case for the IFEN). That neatly sidesteps what happens to a wire-bundle (particularly a vertical one) that is "taken out" by arcing - and what can then happen to electrical systems by way of cascading failure.


J.   CB's  =>  Endorsement here of firmer crew and maint guidance - but also advocating development of CB technology (whilst being careful not to mention AFCI's).


K.   CVR/DFDR/IMAGING =>  Encouraging signs here (as indeed elsewhere) that the investigators are to have their way with all three subjects.


L.   Draft Report  => Defensive about this but I think that it will forever be a "dog with fleas" in their system. Sunshine hearings make a lot more sense.


Overall somewhat anti-climactic and further indepth study of the report will be needed in order to align any thinking with the TSB's presentation.


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