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Old 12th June 2012 | 10:00
  #76 (permalink)  
Microburst2002
 
Joined: Mar 2005
Posts: 1,338
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From: Uh... Where was I?
Absolutely.

I'm talking about the different nature of computers as opposed to mechanical systems.

When computers are involved, wrong data that can't be dismissed by the computers as wrong, can make the computer make very nasty things. The more complex the system is, the more involved one computer in the system and the more systems interface that computer, the worse effects such a malfunction will have.

Wether it is a Boeing or an Airbus, computers are computers.

Computers are protected against that in various manners, like "watchdogs", "voting", control and monitoring dual channels and "dissimilar redundancy". When a computer is not working properly, it is very important that the computer is declared invalid, either by itself or by other computers, so that its outputs are neglected.

The simultaneous and identical freezing of all three pitot tubes will make all three computers be in error, which makes impossible to detect by voting. So it is necessary some added function to avoid that situation, such as probe ice detectors or a "reasonableness check of IAS" using data other than pitot, I think there is already something like that invented.

I'm still curious about what would happen in a B777
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