Safety in Avionics: Swissair’s All-Out War Against Fire

By David Evans | October 1, 2001
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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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