777 seems to be developing a pattern of software related issues..
"THE 777 is the first plane to be designed entirely on computers, with input from pilots from the outset. It is a long-range fuel-efficient workhorse. Since it started commercial operations in 1995, 777s have made more than 2m flights. Boeing claims that operators enjoy a “99% dispatch reliability rate”. In other words, 777s rarely go wrong.
According to one database, there have been only a handful of recent 777 incidents – and two of those were hijackings. The only fatality had been that of an airport worker who was burnt to death when a refuelling operation went wrong in 2001 in Denver, Colorado.
The pilots got much of what they asked for in designing the plane, including a highly automated “glass cockpit” that does away with all analogue gauges and presents flight information on bright, software-driven LCD displays. Integrated into the software is EICAS (engine indication and crew alerting system) which monitors the two engines and alerts the crew to any abnormalities.
Nancy Novaes, an American pilot who flew 777s until she retired last year, said: “This is a great plane to fly. It’s highly computerised, highly logical. It knows what it needs . . . and EICAS tells you what it wants.”
However, the 777 and its computers are not infallible - as investigators knew before last week’s crash.
Early in the evening of August 1, 2005, a Malaysia Airlines 777, en route from Perth, Australia, to Kuala Lumpur was climbing past 38,000ft towards its cruising level when the flight crew were confronted with what the official report on the incident described as “a situation that had previously been considered not possible”.
On the EICAS screen a “low speed” warning appeared, suggesting the plane was approaching the speed at which it would stall. But almost simultaneously, the primary flight display screen warned exactly the opposite: that the aircraft was approaching the overspeed limit, the maximum speed at which it is designed to operate.
Too slow or too fast? Before the crew could decide, the autopilot pitched up the nose and the 777 climbed for 3,000ft, while the air speed dropped from 270 knots to 158 knots - at which point the stall-warning horn correctly sounded and the stick-shakers activated.
The pilot prevented disaster by disconnecting the autopilot and pushing the nose down. But then the autothrottle kicked in, commanding more thrust from the engines. The nose pitched up again and, of its own volition, the aircraft climbed another 2,000ft until it was brought under control.
The plane landed safely but, as the Australian Transport Safety Bureau report put it, the combination of a failed sensor and “a software anomaly” had created an “unexpected situation that had not been foreseen” and for which the crew had not been trained.
The sensor was a tiny “accelerometer” - a device used to measure the plane’s acceleration that is similar to those used in cars to deploy airbags.
Airlines were subsequently warned that they had to modify the plane’s software."
Source:
Hunt for fatal flaw of Flight 38 - Times Online