Re: Silk Air and SR 111

Date:         07 Oct 98 02:49:06 
From:         "Tarver Engineering" <>
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James Matthew Weber wrote in message ...
>While I will concede that a 737-300 and and MD-11 don't have a lot in
>common other than being jet aircraft, I am compelled to notice that both
>the Swiss Air Aircraft and the Silk Air aircraft crashed, and in both
>cases, the FDR and CVR ceased operation well before impact. The lack of
>the CVR and FDR data will no doubt impair the investigation.

In the case of Silk Air the CVR stopped six minutes before the DFDR and that
alone provides information as to the cause.

>I have not heard any good explanations about why the Silkair units
>stopped functioning, and at this stage, there aren't any good reasons
>(but some plausible theories) about why they ceased operating on SR111.

The leading theory is that the Captain pulled the circuit breakers.  He had
reason to be emotionally unstable and a new milti-million dollar life
insurance policy.  Yes, the policy paid.

>I had always been lead to believe that these devices were operated in a
>fashion to allow them to operate under catastrophic failure conditions.
>Apparently this isn't the case. Did the FDR and CVR cease operating in
>the Air Canada 767 that made a dead stick landing at Gimli?

For what reason would these devices stop for the Air Canada 767?  In what
way do you see the Gimily Glider as a catastrophic failure?

>Perhaps it is time that some type of backup power system be mandated for
>these devices so they can run for at least a few minutes after an
>electrical failure. Given that almost all current jetliners are totally
>dependent upon electricity for many functions, it seems to me that it
>may not be such a good idea to design the FDR and CVR in such a way that
>a catastrophic failure prevents you from discovering the nature of the
>catastrophic failure. Discovering what went wrong is the main reason we
>have CVR's and FDR's. It strikes me as somewhat stupid to allow them
>become useless when you need them the most!

The failure of both boxes at the same time in itself is a source of
information.  A basic understanding of how these systems work would help you
see that what you are suggesting is of little value.  The idea of a CVR that
continues to operate is at least popular enough that it might happen in the