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http://seattlepi.nwsource.com/busine...lflight04.html

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High-tech anxiety at 36,000 feet
Twice in two years, crews flying 747s inexplicably had their flight display screens go dark

By JAMES WALLACE
SEATTLE POST-INTELLIGENCER AEROSPACE REPORTER

It's the kind of airplane incident one might expect to find in stories about flights through the Bermuda Triangle.

But it happened on modern jetliners flying between Sydney and Singapore.

Two Boeing 747-400 passenger jets, operated by the same airline two years apart, suffered unheard of failures of all flight display screens in the cockpit -- high-tech anxiety at 36,000 feet.

Both planes landed safely.

The National Transportation Safety Board detailed the two incidents in a letter Tuesday to the Federal Aviation Administration, recommending the federal agency make sure pilots can quickly identify what measures to take if a similar event should occur.

The Boeing Co. said yesterday it does not yet understand how such a failure happened. The 747-400 has a modern glass cockpit, as do other newer Boeing and Airbus jets, in which flight data is displayed to the crew in a battery of large screens. Older jets used analog instruments.

A device called the electronic instrument unit collects data from numerous airplane systems and transmits it to the display screens. This includes engine and navigation data as well as such things as rate of climb or descent, airspeed, altitude and attitude.

This is what happened, based on investigations by the Civil Aviation Administration of Singapore and by the Australian Transportation Safety Board.

On Jan. 23, 2003, a Singapore Airlines 747-400 was at cruise altitude, en route from Singapore to Sydney, Australia, when it experienced a complete loss of information from all six integrated display units on the flight deck instrument panel.......