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Altitude restraints for waypoints?

Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=1077
Printed Date: 04 May 2024 at 1:40am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: Altitude restraints for waypoints?
Posted By: buz914
Subject: Altitude restraints for waypoints?
Date Posted: 23 May 2016 at 12:14pm
If I set an altitude restraint for a waypoint, should the autopilot follow this restraint?  I would think so, but I've gotten conflicting info on this.

In my plane the autopilot does not follow this restraint.  It will however fly a full approach and then go missed and hold.

Can anyone confirm that this works in real life.

Jamie



Replies:
Posted By: mfb
Date Posted: 23 May 2016 at 2:03pm
You do not say what kind of an aircraft or autopilot you have. However, I suspect that the answer to your question is "no."

When you are shooting an approach the IFD is providing a glide slope signal to your nav indicator. The glide slope is displayed as an up/down needle. The autopilot then follows the needle.

I do not believe that the IFD provides a glide slope indication or up/down needle when you are descending to cross a vertical altitude constraint. Certainly the Pilots Guide does not say anything about it. So if there's no glide slope indication, there's nothing for your autopilot to follow,

I have not tried to use vertical constraints much in my IFD540.  But, from reading the Pilot's Guide, it appears that IFD uses them to give you a top of descent (TOD) point and to compute the vertical speed required during the descent. 

Mike


Posted By: oskrypuch
Date Posted: 23 May 2016 at 3:23pm
Originally posted by buz914 buz914 wrote:

If I set an altitude restraint for a waypoint, should the autopilot follow this restraint?  I would think so, but I've gotten conflicting info on this.

In my plane the autopilot does not follow this restraint.  It will however fly a full approach and then go missed and hold.

Can anyone confirm that this works in real life.

Jamie

Not unless your A/P could understand the VSR calculated by the IFD, and hold a VS based on that. I know of no small GA autopilot that can do that, that is fly a non-approach related VPath.

The ability of the IFD to set multiple vertical constraints, and even import the charted minimums on an approach as automatic vertical constraints when an approach is loaded, is one of its most powerful and unique features. But you have to manage the autopilot yourself to fly the VS as calculated and displayed as the VSR by the IFD.

* Orest



Posted By: buz914
Date Posted: 23 May 2016 at 9:40pm
I'm flying an RV-10 experimental with AFS EFIS and autopilot.  Capable of flying a V/S. I guess the 540 just does not give this command to the autopilot.  I can see where its helpful in planning climbs and descents, but you have to do the autopilot part manually.  Just don't see why the 540 can't give this info to the autopilot.  It does everything else?!

FYI- After speaking to AFS(Advanced Flight Systems EFIS), the EFIS will automatically mirror the flight plan of the 540 and altitude restraints can be added to the waypoints there. Exactly as they are on the 540. And the autopilot will fly it.


Jamie


Posted By: oskrypuch
Date Posted: 23 May 2016 at 9:58pm
Many autopilots will fly a vertical speed, not the same thing as flying a calculated vertical path (VPath). My comment was regarding certificated equipment in small GA planes.

* Orest




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