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Crash probe reveals shortcomings in cockpit design

Investigators are piecing together the remains of the aircraft Keystone Archive

Investigators probing the crash of a Swissair plane off the Canadian coast in 1998 say the pilots may have had trouble reading emergency instruments.

Investigators from the Canadian government’s Transportation Safety Board said that badly located emergency gauges on the MD-11 aircraft could have contributed to the disaster, which claimed 229 lives.

In its safety advisory letter, the board recommended an industry-wide review of the design and location of emergency gauges in the MD-11.

The document suggests that the pilots of the doomed aircraft had difficulty reading emergency instruments showing altitude and speed of the plane in the minutes leading up to the crash, off the coast of Nova Scotia.

“The result of our investigation indicates that there was a tremendous workload in the cockpit during the emergency”, Daniel Verreault, director of air investigations for the board, told swissinfo.

“It is clear that the crew were under significant pressure to not only fly the plane, but to also manage the emergency, which in this case, was fire and smoke related.”

Electrical failure

The plane is believed to have crashed after a massive electrical failure. At the time, the autopilot and primary instrument displays were disengaged and the crew were forced to use back-up instruments.

According to the advisory papers, these gauges are “awkwardly” located requiring the pilot to turn around to read them. It says this uses up valuable seconds, critical in an emergency situation, when pilots are struggling to control an aircraft.

“Emergency instruments were not located in the same area,” Verreault said.

“For instance, the stand-by magnetic compass was located at the top of the windshield when other basic standby instruments (including airspeed and attitude) were located at the bottom of the instrument panel. This would have required them to move their heads to keep aware of information.”

Cockpit overhaul

The investigators have now called for a general overhaul of the location of these instruments in the cockpit.

“It is our belief that a redesigned cockpit which would provide the crew with a “get home package” (which includes simple instruments, individually powered, located in the cockpit) would have eased the crew’s workload and thus given them a better chance of managing the emergency,” Verreault told swissinfo.

It is not clear whether better-located instruments could have prevented the Swissair crash but, according to Verreault, better design “would have simplified the pilot’s work.”

Secondary power source

The Transport Safety Board also suggested that communication and navigation equipment should be powered by a secondary on-board source so that if an electrical fault or accident occurs, pilots do not have to switch to emergency instruments.

Swissair modifications

The board has praised Swissair’s modification of the standby flight instrument equipment in their aircraft in the wake of the tragedy.

“For their MD-11 aircraft, they chose to install a secondary flight display system (SFDS), which has a similar layout to the primary flight display in that aircraft,” the advisory letter said. The SFDS includes airspeed, altitude, attitude and heading in one display.

In the event of an electrical meltdown, it has a battery to supply power for a minimum of 45 minutes.

“Now we are looking on the world to follow the lead of Swissair and to adopt similar design philosophy changes,” Verreault said.

Identifying cause unlikely

“We will likely never know exactly what happened during those six minutes in the cockpit” between when traffic controllers last heard from the pilots and when the plane went down, Verreault said.

But the board has made practical recommendations in previous reports to improve aviation safety. These measures include ensuring that blankets used on board are anti-flammable, and that improved fire-fighting equipment is placed on all aircraft.

The final report into what caused the Flight 111 Swissair crash is due out next year, but investigators do not know if they will ever be able to determine what happened.

by Samantha Tonkin and Sally Mules

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SWI - a branch of Swiss Broadcasting Corporation SRG SSR