HALIFAX - Investigators believe electrical arcing in the cockpit
ceiling is the most likely cause of a catastrophic fire that brought down
Swissair flight 1-11 killing all 229 on board.
The Transportation Safety Board report into the 1998 crash off Peggy's
Cove, Nova Scotia says the fire rapidly spread through insulation and
other flammable materials knocking out all of the MD-11's critical
systems.
After painstakingly reconstructing about 98 per cent of the jet from
recovered wreckage investigators can't say with certainty, but they
believe the main arcing event happened on the right side of the cockpit
near the rear wall.
The suspect wire was one of the cables that supplied power to the jet's
inflight entertainment system.
The board concludes the fire moved so quickly that even if the pilots
had diverted to Halifax the minute they first smelled the smoke they still
would not have had enough time to land safely.
Many of the board's 23 recommendations have already been implemented
including the removal of highly flammable acoustic insulation blankets to
tighter policies for the certification of inflight entertainment systems.
``Investigators believe that this arcing event on the entertainment
system wire was associated with the initial arcing event,'' the agency
said in a release.
``However, investigators could not pinpoint this as the lead event.''
The board said it had recovered 20 pieces of wire from the shattered
remains of the plane that showed melted copper, indicative of arcing
damage.
Vic Gerden, the agency's lead investigator, said this was likely not
the only wire involved in the arcing.
``We strongly suspect that at least one other wire was involved, either
an aircraft wire or another entertainment system wire,'' he said in a
statement.
Investigators also determined the pilots acted appropriately in not
trying to land the plane immediately, something critics have argued would
have saved some or all of the 229 people who died in the crash.
The pilots spent valuable minutes trying to identify the source of the
fire after smelling smoke 53 minutes into the flight. They diverted away
from the Halifax airport to dump fuel over the ocean after having a near
full load since leaving New York for the transatlantic trip.
The board did a theoretical ``descent profile'' and found the pilots
would ``not have been able to complete a safe landing in Halifax, even if
they had undertaken to do so at the time of the PAN PAN urgency radio
communication,'' the report says.
The agency, which has spent $60 million and 4{ years examining millions
of pieces of wreckage in the case, issued nine new recommendations. Two
address testing and flammability standards of thermal acoustic insulation
materials.
It also recommended improved certification standards for planes' add-on
systems, such as the entertainment system.
Four recommendations propose improvements to how information from the
flight data and cockpit voice recorders is captured and stored.
Some aviation experts believe the entertainment unit is key to the
fire. Critics have said the system was so hastily installed on the MD-11
that the proper inspections weren't done to ensure it could operate safely
in the air.
One avionics expert called it a ``power-hungry monster'' that demanded
an excessive amount of energy. Critics have blamed the U.S. Federal
Aviation Administration in part for allegedly shirking its duties in
certifying the system _ something they said the safety board should have
addressed in its report.
The system, which allowed passengers to gamble, play video games and
watch movies, was found on test flights to raise cabin temperatures and
cause hard drives in the seats to fail.
The board has released several recommendations and advisories over the
course of the investigation. They have included calls for more stringent
testing of electrical wiring in aircraft, inspection of cockpit wiring of
all MD-11s and independent power sources for flight recorders.
In 1999, after investigators determined that metallized Mylar
insulation on the plane helped to spread the fire, the FAA ordered
U.S.-registered airplanes to replace the material within four years.
``It is important to emphasize here that without the presence of this
and other flammable material, this accident would not have happened,''
Gerden said.