HALIFAX (CP) - Wiring that fed a controversial entertainment system
aboard Swissair Flight 111 likely contributed to a fire that brought the
plane down off Nova Scotia in 1998, investigators said Thursday.
The Transportation Safety Board didn't identify the exact source of a
fire that led to a massive electrical failure aboard the MD-11 jetliner,
but concluded it was linked to the system.
In a 337-page report, the agency said the fire started when wire arced
above the ceiling on the right side of the cockpit. The arcing - a
phenomenon in which a wire's coating is corroded and can lead to sparking
- ignited a flammable insulation covering, allowing the fire to race
through the plane's wiring system.
"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.