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simon-flight

RNAV approaches with GTN650

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Hi Guys,

Has anyone flown an L/VNAV approach with the Flight1 GTN650 and had the CDI GS needle work ?.

I've tried many times and always had a red flag. (ILS works fine)

 

Strangely, if the autopilot is setup the aircraft pitches down at the correct fix and can fly the approach but just no needle movement.

Anyone have the same experience ?

 

One of the approaches I have been trying  is ENHD RNAV 14 GPS LNAV/VNAV

 

Best Regards

Simon Grant

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Simon, I don't think the GTN650 is certified for VNAV approaches.  A quick browse of the Garmin manual (you should get when you download the trainer), only mentions using it for vertical guidance in descent (ie, keeping a steady 1000 fpm descent).  Also, if any vertical guidance is to be provided to the FD or AP it requires specific things and I don't think the old Sperry in the DC6 is going to interface well.

I always assumed that only lateral guidance was provided, and I doubt you will see anything tighter than 0.3nm.

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Hi downscc

 

That all makes perfect sense about the sperry, but doesn't vertical guidance mean the GS needle on the CDI should be moving ?

 

Best Regards,

Simon Grant

 

 

 

 

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7 minutes ago, simon-flight said:

That all makes perfect sense about the sperry, but doesn't vertical guidance mean the GS needle on the CDI should be moving ?

True, I would guess that the vertical deviation is not connected to the CDI instrument.  I know in our Chancellor the GNS530s have vertical guidance for descent but do not drive the glide slope needle.... kinda makes sense. It is not a precision descent.

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On 11/8/2017 at 0:50 PM, downscc said:

True, I would guess that the vertical deviation is not connected to the CDI instrument.  I know in our Chancellor the GNS530s have vertical guidance for descent but do not drive the glide slope needle.... kinda makes sense. It is not a precision descent.

Here is some good background material for all who are interested:

 

http://www.aviationsafetymagazine.com/issues/36_4/features/RNAV-Approach-Types_11164-1.html

 

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On 11/14/2017 at 10:09 AM, AirCanada235 said:

Gents,

Dan is correct on the RNAV GTN650 VNAV approaches.  Its advisory vertical guidance only.

A quote from page 6-2 of the GTN650 manual

"The GTN 6XX provides precision vertical guidance as well as lateral and advisory
vertical guidance using its built in GPS receiver for GPS or RNAV approaches."

 

A look at the chart on page 6-3 shows that it is indeed certified to fly precision approaches to LPV and LNAV/VNAV minimums using a decision altidute.

Other modes such as LNAV+V provide only advisory vertical guidance.

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3 hours ago, JoeDiamond said:

A quote from page 6-2 of the GTN650 manual

"The GTN 6XX provides precision vertical guidance as well as lateral and advisory
vertical guidance using its built in GPS receiver for GPS or RNAV approaches."

 

A look at the chart on page 6-3 shows that it is indeed certified to fly precision approaches to LPV and LNAV/VNAV minimums using a decision altidute.

Other modes such as LNAV+V provide only advisory vertical guidance.

Well done Champ.  Not sure how to award you points or anything but nice find

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Hi Folks,

FYI: If you have WAAS - even the GNS will fly precision approaches with vertical guidance - coupled to an STEC-65 will fly you right down to DA...

Regards,

Scott

 

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Hi Guys,

I really appreciate all the input, looks like I have some reading to do as well.

Apologies if this is a dumb question, but shouldn't advisory vertical guidance mean the GS needle should move ? otherwise how is it guiding the vertical part of the procedure ?

Thanks and Regards

Simon

 

 

 

 

 

 

 

 

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1 hour ago, simon-flight said:

but shouldn't advisory vertical guidance mean the GS needle should move

Yes.

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