Re: 747 Question. Are there any EFIS experts out there?

From:         Tony Maddern <>
Organization: University of New South Wales
Date:         21 May 96 11:10:52 
References:   1
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The VS on the -400 is sourced from the IRS but is passed through the
Air Data Computer on its way to the PFD so it may well be smoothed by
the ADC. You can check this by failing the ADC and the VS display will
be removed from the PFD. The best way to resolve the bet is to obtain
a look at the System Description Document (SDD) in your company's
technical library.
I used to fly for Cathay Pacific and did my -400 endorsement in 1988
but the system should not have changed too much.
Regards, Tony Maddern