Swissair crash probe reveals shortcomings in cockpit design

Investigators are painstaking 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 released a report which found that badly located emergency gauges on the MD-11 aircraft could have contributed to the disaster, which claimed 229 lives.

The board is demanding 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.

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.

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

“The location of instruments is very important,” said Daniel Verreault , the director of air investigations for the board. “If you have standby instruments that are not well located, you add to the complexity, and in the scenario of fire and smoke, as we had with flight 111, you’re adding to the workload.”

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.

In addition, officials are looking into the possibility of creating a so-called “get-home package” which would provide flight data in the event of an electrical meltdown on board an aircraft.

Verreault added that the advisory documents would also be shared with the National Transportation Safety Board in the United States and the Federal Aviation Administration.

Swissair modifications

In the wake of the accident, the report said that Swissair modified the standby flight instrument equipment in their aircraft.

“For their MD-11 aircraft, they chose to install a secondary flight display system (SFDS), which has a similar layout to the primary flight dislay in that aircraft.” 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.

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.

swissinfo with agencies