[Info-vax] OT: Aircraft pitot tubes and clustering.

[Bob Koehler]

In article <00a698de$0$26911$c3e8da3 at news.astraweb.com>, JF Mezei <jfmezei.spamnot at vaxination.ca> writes:
> 
> Sort of interesrting because I guess when they designed the aircraft,
> they had not considered cases where 2 failures would happen at same time
> and with the same amount of error, causing the one remaining valid
> sensor to be kicked off and the erroneous values to be used since their
> have "quorum" betwen themselves.

   Generally tripple redundancy is used in cases where human life is
   being protected.  During design and implementation the possibility
   of double failures is investigated and the causes are worked on to
   bring the likelyhood to a very small value.  It is often impossible
   to eliminiate.

   With tripple redundancy there is always the possibility of system
   failure due to double faults.

   You want to fly in a nice, safe airplane?  Make sure it has exactly
   one engine, make sure it's a piston engine, and make sure there's
   a real human being in control, with no electronic gadgets between
   him/her and the control surfaces.  And fly within gliding distance of
   land, or make sure it's a seaplane.

   Why not two engines?  Light twins are the most dangerous airplanes
   in the sky, they're very hard to operate on one engine and the accident
   rate while trying to continue on one engine is very high.  In theory
   they can be flow on one engine so pilots will try to fly to an
   airport, but they don't always have enough practice to succeed.
   Since there are two of them, the engines don't have to be as reliable 
   as the engine in a single engine aircraft, although they tend to be 
   built in a similar manner.  By comparison, on the exceedingly rare 
   failure of a the only engine every pilot will look for a safe place 
   to glide to, and success rates are quite high.

   Why a piston engine?  When you need power they rspond, while
   turbines take time to spool up.

   Oh, yes, I have hundreds of hours piloting those safe little airplanes!

   And I still feel safer in a Boeing than an Airbus.