which procedure turn?
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=1460
Printed Date: 18 Apr 2024 at 11:01pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: which procedure turn?
Posted By: wsh
Subject: which procedure turn?
Date Posted: 09 Feb 2018 at 6:30pm
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a couple of weeks ago I was flying approaches at Rotterdam (EHRD) airport. For one approach I asked to do the full approach including procedure turn and did it on autopilot in GNSS mode. I was surprised to see that the IFD540 chose to do the procedure turn for cat c & D aircraft (which is a bit larger turn obviously for higher speed). How can I see and know what procedure the IFD will chose?
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Replies:
Posted By: wsh
Date Posted: 09 Feb 2018 at 6:39pm
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The procedure http://www.ais-netherlands.nl/aim/2018-01-18-AIRAC/graphics/eAIP/EH-AD-2.EHRD-IAC-06-1.pdf" rel="nofollow - http://www.ais-netherlands.nl/aim/2018-01-18-AIRAC/graphics/eAIP/EH-AD-2.EHRD-IAC-06-1.pdf ? also for some reason it tends to overshoot on the ROT1R approach http://www.ais-netherlands.nl/aim/2018-01-18-AIRAC/graphics/eAIP/EH-AD-2.EHRD-IAC-24-2.pdf" rel="nofollow - http://www.ais-netherlands.nl/aim/2018-01-18-AIRAC/graphics/eAIP/EH-AD-2.EHRD-IAC-24-2.pdf ? |
Posted By: DavidBunin
Date Posted: 10 Feb 2018 at 11:20am
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That is interesting. I suspect the real answer is that it is doing neither. The procedure turns I am used to in the United States are all a 45° turn from the approach course. In this case, that would be a heading of 282° which is between the 273 and 291 shown on your chart. While I am far from an expert, I don't recall having different procedure turns for aircraft categories on my NOAA approach plates. With any luck, a more experienced instrument pilot will also reply. |
Posted By: mfb
Date Posted: 10 Feb 2018 at 12:12pm
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In the US you can do anything you want to accomplish a course reversal (procedure turn), as long as you stay in the protected airspace. That airspace is defined by the US Standards for Terminal Instrument Procedures (TERPS). I'm sure that the TERPS accounts for aircraft speed, but I have never seen a specific differentiation between category A, B, C, and D aircraft. I have no idea if European standards are different from the US ones. I suspect that David is correct. The IFD is simply doing a generic course reversal which stays in the protected TERPS airspace. It's probably not trying to follow a specific line on a chart. But that's just a guess. Mike |
Posted By: AviSteve
Date Posted: 12 Feb 2018 at 10:22am
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Historically, in cases where there were different paths for
different categories of aircraft, Jeppesen would code the database for the
highest category of aircraft. That's why
you're seeing the larger procedure turn.
For several years, however, they have been adding the differing paths as
separate transitions, using trailing numerals to provide a distinction in the
name. For instance, at Townsville
airport in Australia, the VOR/DME19 approach has a transition named
"TL" having different paths for A/B and C/D categories. In that case, the C/D transition is named
"TL1" and the A/B transition is named "TL2". ------------- Steve Lindsley Avidyne Engineering |
Posted By: paulr
Date Posted: 12 Feb 2018 at 6:25pm
| Thanks, Steve. I appreciate you being willing to jump in and give an engineering-based answer, and even more so that you went to Jepp to get them to fix the issue. May your reign be long. |
Posted By: wsh
Date Posted: 15 Mar 2018 at 3:04am
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Well done... Can you also ask them to look into the ROT 1R approach? The autopilot will not fly this onecorrectly as it will overshoot the turn onto final. |
Posted By: AviSteve
Date Posted: 15 Mar 2018 at 9:55am
It looks OK to me in the database. As approaches go, it's about as plain vanilla as you can get. What's your 429 and 232 config? Is your autopilot flying roll steering? If so, at what point does it switch to VLOC? Any chance of you getting video of it happening? ------------- Steve Lindsley Avidyne Engineering |
wsh wrote:Posted By: jhbehrens
Date Posted: 15 Mar 2018 at 6:29pm
| Perhaps Jeppesen incorrectly coded EH241 as a fly over instead of a fly by waypoint? |
Posted By: luchetto
Date Posted: 15 Mar 2018 at 6:41pm
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Steve your question is raising my interest as I have reported more than once that my KFC150 ap mostly turns into the wrong direction when intercepting the final approach course during a vectored approach. Our interception angle is usually less than 30 degrees. the gps vloc switch happens extremely late so that I end up switching manually. I never understood why sometimes it turns correctly into the final approach course and the next time it turns away from it. Your remarks about the settings is raising my interest, could this be at the source of my problems? |
Posted By: AviSteve
Date Posted: 15 Mar 2018 at 9:46pm
That was my first thought too, but I checked the raw navigation database and it's not flyover. ------------- Steve Lindsley Avidyne Engineering |
Posted By: AviSteve
Date Posted: 15 Mar 2018 at 10:53pm
If the autopilot is using deviations, I would expect it to turn away from final when you're outbound on a course reversal. But if you're inbound on a vectors to final, and you are on course to intercept the active leg, I wouldn't expect it to turn the wrong way. It's unlikely that your settings are the source of the behavior you're reporting, though. ------------- Steve Lindsley Avidyne Engineering |
Posted By: AviSteve
Date Posted: 16 Mar 2018 at 9:47am
Can you post some specific examples of approaches where the autopilot turns away from final and some other examples where it turns the correct way? ------------- Steve Lindsley Avidyne Engineering |
Posted By: luchetto
Date Posted: 16 Mar 2018 at 3:15pm
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Steve, I don‘t have videos of it but I have experienced this behaviour multiple times on the ILS 14 approach into LSZH. I am usually coming from the south on the kelip 1 golf arrival and then I get vectored. The final heading I get is 110. The AP is in heading mode with APP armed. Instead of turning right the airplane turns left. This happens most of the times but not always that‘s why I don‘t understand it. The only difference might be my altitude as Zurich Arrival has a tendency to keep GA too high. What drives my crazy is that the few times it works I have no indications why. |