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Safety in Avionics: Swissair’s All-Out War
Against Fire
By David Evans
No airline has suffered more from the ravages of in-flight fire
than Swissair. No airline is doing more than Swissair to ensure that
it does not happen again. Only Swissair pilots will have a cockpit
display providing a picture of smoke and fire in concealed
spaces.
At an aggressive schedule of two to three airplanes per month,
Swissair plans to cycle its fleet of 19 MD-11s through what it has
dubbed the "Modification Plus" program. The upgrade is a direct
outgrowth of the fatal 1998 crash near Halifax, Nova Scotia, Canada,
of a Swissair MD-11, in which all 229 aboard were killed. From what
can be gleaned from the reconstructed wreckage, an uncontrolled
in-flight fire probably doomed the airplane. What most likely
started the fire was electrical arcing in the area between ceiling
panels and the thermal/acoustic insulation blanketing in the cockpit
overhead area.
The accident struck the carrier like a gunshot. Although the
exhaustive investigation by the Canadians is far from complete,
Swissair officials feel they know enough to take steps now.
The Modification Plus program, at $650,000 per airplane, features
four major elements:
Rerouted electrical cables and wires. Power feeder cables,
installed running together, have been separated. According to an
internal Swissair bulletin, the change in wire routing is "to
enhance wire separation and increase redundancy whenever
feasible.
"Generally speaking, the changes are based on the idea that the
left power feeders are routed through the left side of the cockpit
and the right power feeders are routed through the right side," the
bulletin explains. These changes are significant, as Canadian
investigators of the accident near Halifax found about a dozen
heat-damaged wires around the circuit breaker panel—compelling
evidence of the likely location where the fire started on the
aircraft.
Concealed cameras. A battery of surveillance cameras has
been fitted in three areas of the airplane deemed particularly
vulnerable to in-flight fire: two in the avionics bay underneath the
cockpit, two in the cockpit overhead area, and three in the ceiling
area above the first-class cabin and galley area.
In many respects, the camera installation reflects the need cited
by the UK’s Air Accidents Investigation Branch (AAIB) for better
fire detection in the aircraft’s inaccessible areas. This finding
stemmed from the AAIB’s investigation into the January 1998 incident
in which arcing in the avionics bay forced the crew of a United
Airlines B767 to abandon a westbound trans-Atlantic flight from
Zurich to Washington-Dulles and divert to London’s Heathrow Airport
(February 2001, page 42).
The heat-resistant cameras being installed in the Swissair jets
are connected to a cockpit viewing screen, giving aircrews a
real-time picture in the event of a smoke alarm. A switch enables
the crew to select the view from each camera.
Improved firefighting. Capt. Ruedi Bornhauser, Swissair
MD-11 technical pilot, exclaims that the Modification Plus upgrade
also provides, for the first time, "a real firefighting capability,
which does not exist on any other aircraft."
"We have Halon bottles in fixed installations in the cockpit and
in the sidewalls of the first-class galley," he explains. "If we
realize that the smoke is real, caused by a fire, we have a chance
to fight it with the 5-pound Halon bottles [that] we can discharge
into the cockpit overhead area."
"We have two 10-pound bottles for discharge into the galley
overhead area. There is, as well, a ‘fixed tube’ system where we can
distribute Halon to the most important area in that compartment,"
Bornhauser adds. "This is a major improvement."
Upgraded standby instrument. Swissair is installing a
brand-new standby, or secondary flight display (SFD). Essentially,
it is a mini-primary flight display (PFD), with the artificial
horizon in the center flanked by a speed tape on the left and an
altitude tape on the right. This instrument has dual power sources
with separate, independent wiring.
Bornhauser, regarded as a motivating force behind the
Modification Plus program, says its primary purpose is to "provide
early recognition of a critical situation." When it comes to the
threat of in-flight fire, he explains, "time is the most important
factor. To gain five, 10 or 15 minutes can be lifesaving."
Bornhauser believes the upgrade not only provides "a higher level
of safety," but it also should boost crew confidence:
"Psychologically, you are aware of having a sophisticated
surveillance system in place that will warn earlier than in any
other aircraft if something goes wrong."
Swissair also plans to install similar upgrades into its fleet of
57 Airbus aircraft and will seek to have the cameras and other
Modification Plus features factory-installed in the A340-600s it has
on order.
Regarding the money the Swiss carrier is spending, Bornhauser was
commendably blunt about priorities. "Airlines are spending money
like crazy for things in the cabin, such as for laptops, e-mail and
Internet access—all kinds of things really not needed in an airplane
from a pilot’s point of view," he declares. "This is just
marketing-driven—you spend more money and it has nothing to do with
safety…You should invest the money, rather, in increased safety of
the transport and not in the entertainment of the passengers."
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2001 Avionics News and Highlights
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