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Europa-List: Re: More on VNE

Subject: Europa-List: Re: More on VNE
From: Mark Burton <markb@ordern.com>
Date: Sun, 23 Sep 2007 13:29:08

Yes, but why not RAS or CAS given that IAS is not necessarily accurate due to 
position
or instrument errors?

For example, I know that the ASI on my own aircraft progressively under-reads as
speed is increased. However, if I change the static to use cockpit static, it
then over-reads at low speed.

One of my customers who fitted a SmartASS talking ASI queried the fact that it
was reporting quite different speeds to their mechanical ASI and, subsequently,
discovered that their mechanical  ASI was actually untrustworthy and needed
replacing. From memory, I think their ASI had been under-reading.

The point I am making is that the average ASI system (pitot, static, instrument,
plumbing, position errors, etc.) is very unlikely to deliver an accurate IAS
(within, say, +/- 1%).  This rather makes a mockery of the PFA's requirement
to fly at VNE within one indicated speed unit. 

If you think about it, it's rather a chicken-and-egg situation because how can
you check the accuracy of your ASI at VNE without flying at VNE (as indicated
by the ASI!)?

Mark


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http://forums.matronics.com/viewtopic.php?p=135944#135944



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