G5 HSI CDI deflection under VLOC

sarangan

Pattern Altitude
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Jun 7, 2008
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Andrew, CFI-I
I am somewhat new to the G5, and I've been having some issues with the G5 HSI. Under VLOC, I am not getting the green CDI needle unless I am within about 10-deg of the selected course. No CDI needle makes makes me think we are not receiving any signal. But I can receive it just fine with the NAV2 radio which is tied to a traditional CDI (which shows a full scale deflection, as expected). Under GPS mode, however, the HSI shows a CDI no matter how far off the selected course I am. So this behavior seems specific to VLOC only. Has anyone else experienced this?
 
The full-scale limits for the CDI are defined by a GPS-derived distance when coupled to GPS. When coupled to a VOR or localizer (LOC), the CDI has the same angular limits as a mechanical CDI.

If you are outside of 10° you shouldn’t pick it up correct?
 
The full-scale limits for the CDI are defined by a GPS-derived distance when coupled to GPS. When coupled to a VOR or localizer (LOC), the CDI has the same angular limits as a mechanical CDI.

If you are outside of 10° you shouldn’t pick it up correct?

I was expecting it to show full scale deflection when the deviation is more than 10 deg, just like the old mechanical CDI. Instead, it seems to show no CDI. That makes it difficult to figure out which side the course lies.
 
That makes it difficult to figure out which side the course lies.

That is what we have iPads, GNS/GTNs and near 100% radar coverage...so we don't have to guess anymore.
 
The logic is that you use GPS until you're close enough to start getting sensitivity..
 
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