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1 minute holds, adjusted inbound and outbound legs

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=2379
Printed Date: 15 Jul 2024 at 11:45pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: 1 minute holds, adjusted inbound and outbound legs
Posted By: Mac57
Subject: 1 minute holds, adjusted inbound and outbound legs
Date Posted: 03 Jul 2022 at 12:29am
I am currently taking IFR lessons and working on holds.  When setting up a 1 minute hold, the IFD 440 draws the magenta track.  Is the track displayed, being compensated for the prevailing winds?  In other words, if I fly the exact track (or the auto pilot flies it), does the track adjust for inbound and outbound legs to provide for a 1 minute inbound track. It does not appear to be when I fly this type of hold, but it was really close when timing the inbound and outbound legs.  Also, are there any data blocks that may provide info to help with timed holds?

Thanks,
Mac


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Mac



Replies:
Posted By: dmtidler
Date Posted: 03 Jul 2022 at 11:13pm
My observation is that depicted hold size adjusts based on the aircraft's GPS groundspeed upon each and every crossing of the holding fix.

For timed holds, this generally means that if you arrive at the holding fix for a teardrop or parallel entry at the target holding airspeed, the entry size will be based on the tailwind GS crossing the holding fix for the entry and thus, the first inbound leg time may be over the target inbound leg time.

The opposite would be generally true for headwinds going into a teardrop or parallel hold entry.

Generally, for timed holds with direct entries and certainly for each established holding pattern, the GS used to determine the hold size upon each hold fix crossing will be primarily along the holding inbound leg and should result in quite accurate inbound leg timing as long as the winds and holding airspeed remain steady.

In other words, after the second crossing of the holding fix, the inbound leg time should be quite accurate with steady winds and airspeed for timed holds.


Posted By: PA23
Date Posted: 07 Jul 2022 at 10:51am
Originally posted by Mac57 Mac57 wrote:

I am currently taking IFR lessons and working on holds.  When setting up a 1 minute hold, the IFD 440 draws the magenta track.  Is the track displayed, being compensated for the prevailing winds?  In other words, if I fly the exact track (or the auto pilot flies it), does the track adjust for inbound and outbound legs to provide for a 1 minute inbound track. It does not appear to be when I fly this type of hold, but it was really close when timing the inbound and outbound legs.  Also, are there any data blocks that may provide info to help with timed holds?

Thanks,
Mac


The magenta line drawn on the screen is based upon a ground track, it is not going to give you the heading you see on your DG.

In terms of following the line to make your turns, not sure I'd do that, I'd still time your turns (or allow the IFD to time them for you) but not turn because the line shows the turn.



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