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  #1  
Old 11-19-2013, 03:37 PM
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walkman walkman is offline
 
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Default GRT Autopilot fly a pre-programmed vertical non-approach descent?

Lets say I'm cruising along at 11,500 and want to be at 3,000 a couple of hundred miles down the road, and I want to descend at a set pre-determined airspeed or vertical speed, can I do it?

I can set up the descent on the 430w, but it just tells me when to start the descent what altitude to be at during the descent. It doesn't send that info to the a/p.......or can it?

I can set up an altitude and rate in the a/p and do it NOW, but is it possible to set it up to have it happen when I get to the descent point?
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  #2  
Old 11-19-2013, 05:09 PM
BobTurner BobTurner is offline
 
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To the best of my knowledge, no. With some work you could program in the calculated descent point as a waypoint in your gps flight plan, just as a reminder of when to initiate the descent.

You know about the green arc on the map, using it to adjust the descent rate?
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  #3  
Old 11-19-2013, 08:20 PM
BillSchlatterer BillSchlatterer is offline
 
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Default Sure, altitude preselect works well!

Quote:
Originally Posted by walkman View Post
Lets say I'm cruising along at 11,500 and want to be at 3,000 a couple of hundred miles down the road, and I want to descend at a set pre-determined airspeed or vertical speed, can I do it?
Yes, with at least a GRT H1 and assuming a TruTrak AP like the DII VSVG altitude preselect works well. Assuming the AP is engaged and you are cruising at 11,500, you go to the PFD, select 3,000 with the right knob. It should prompt you to select either a vertical descent rate (-XXX per minute) or airspeed. I have mine set to prompt for vertical descent rate. It will push over and descend at -XXX feet per minute and then level at 3,000. Picking your descent rate sets the distance covered while descending. Works the same in climb.

Hope that helps.
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  #4  
Old 11-19-2013, 11:20 PM
BobTurner BobTurner is offline
 
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Bill, you misunderstood the question. He wants to program the autopilot now, to begin a descent at some fix 100 miles away. Basically, he'd like to have a vertical flight plan, just like the usual horizontal one. I do not know how to do that.
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  #5  
Old 11-20-2013, 09:15 AM
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I know about the green banana. I'd sort of like to do a "fly to the green banana" if that makes any sense.

Say I need to be under a class b shelf, or crossing a fix at a certain altitude, and I want to descend at a given speed or rate, have the a/p trigger its descent when it calculates its time.

sounds like its not doable.
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  #6  
Old 11-20-2013, 09:40 AM
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RV8iator RV8iator is offline
 
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You're correct. You can't preprogram it to do this. Like stated above, you could make a vnav waypoint to alert you of the need to descend, but the a/p won't fly the vertical feature without input from you.

I use the green arc to double check my mental calculations when I set in the preselected altitude.

We'd need an FMS with VNAV functions to do what you're asking.

I just calculate the time/distance required to be at a certain place/altitude and set the Rate of Descent and then when the green arc stabilizes I fine tune it. works like a champ.
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Last edited by RV8iator : 11-20-2013 at 09:42 AM. Reason: clarity
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  #7  
Old 11-20-2013, 12:11 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by walkman View Post
I know about the green banana. I'd sort of like to do a "fly to the green banana" if that makes any sense.

Say I need to be under a class b shelf, or crossing a fix at a certain altitude, and I want to descend at a given speed or rate, have the a/p trigger its descent when it calculates its time.

sounds like its not doable.
Just because no one does it doesn't mean it isn't doable - I have been asking for the same thing from numerous manufacturers for a long time - maybe someday we'll get it. Would really be handy !
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  #8  
Old 11-20-2013, 12:16 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by Ironflight View Post
Just because no one does it doesn't mean it isn't doable - I have been asking for the same thing from numerous manufacturers for a long time - maybe someday we'll get it. Would really be handy !
I agree. I'd really like to pre program my flights to miss certain airspace floors. I was shocked when I started flying the -8 with all the "magic" on board that this isn't an option. Does not seem like it would be that hard.
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  #9  
Old 11-20-2013, 12:39 PM
TrutrakTech TrutrakTech is offline
 
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Quote:
Originally Posted by Ironflight View Post
Just because no one does it doesn't mean it isn't doable - I have been asking for the same thing from numerous manufacturers for a long time - maybe someday we'll get it. Would really be handy !
The Trutrak Sorcerer has a built in VNAV function that allows you to program a descend-to altitude over a certain distance. It will automatically adjust the descent rate with changing speed to maintain the profile and arrive at the target altitude by the specified distance. It isn't automatically tied to a waypoint or fix, but it does give you a way to descend under an airspace shelf simply by your distance from the edge of it. Just thought I'd put that out there.
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  #10  
Old 11-20-2013, 01:50 PM
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Garmin G3X does this. VNAV.
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