Garmin G500 Lateral deviation scale question

[NotarPilot]

It appears that the lateral deviation scale on the G500 has 4 degree spacing per dot as opposed to 2 degrees per dot on a standard CDI.  Can someone confirm this and explain why Garmin did this?

[201Mooniac]

From the G500/G600 Pilots Guide:

 

The full-scale limits for the CDI are de ned 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.

[Bryan]

I was thinking the same thing.  In GPS mode the CDI limits are changed by what mode you are in: Enroute, Terminal, Approach

I think it should be:

Enroute: (+-) 5.0nm   or   (+-) 2.0nm WAAS
Terminal: (+-) 1.0nm
Approach: (+-) 0.3nm

I am having flashbacks of my IFR testing.

[NotarPilot]

I’m referring to the marks of degrees of deflection as shown in the comparison below. The G500 only has two dots on each side while a standard HSI has 5 and VOR CDI has 4 on either side of the circle.

Edited June 6, 2018 by NotarPilot

[carusoam]

Great pics, notar...

Great question, too...

Let’s get the CFII with the all G panel involved...

@donkaye

I bet Don knows the answer... 

Best regards,

-a-

[kpaul]

13 hours ago, NotarPilot said:

The G500 only has two dots on each side while a standard HSI has 5 and VOR CDI has 4 on either side of the circle.

I am not sure there is a "standard"  as you have shown in your pictures.  All the glass I have flown behind has only had the 2 per side ( half and full scale deflection).  The goal is to have it centered, no?  or to know when established, 5 degrees on NDB, half scale on VOR, case break on the localizer.

[Marauder]

I am not sure there is a "standard"  as you have shown in your pictures.  All the glass I have flown behind has only had the 2 per side ( half and full scale deflection).  The goal is to have it centered, no?  or to know when established, 5 degrees on NDB, half scale on VOR, case break on the localizer.

Yeah, I never really paid much attention to the dots on my Aspens but I have 4 dots for either GPS or ILS approaches. The AI in this picture also shows the 4 dots in the horizontal and vertical course indicators.

 

[PTK]

What's important is the sensitivity and the nav source i.e. GPS or VLOC, not the number of dots or circles.  The sensitivity changes depending on segment of the flight. Enroute, terminal or approach. For example with GPS as the source the Enroute (ENR) sensitivity is 5 nm full deflection or 2.5 nm per circle. For terminal area (TERM) which I believe iirc is a radius between 2 and 30 nm from airport the sensitivity is 1 nm full deflection or 0.5 nm per circle. On approach within 2 nm radius of FAF the sensitivity becomes 0.3 nm in full deflection.