Check Navaid ID
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=734
Printed Date: 03 May 2024 at 11:17pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Check Navaid ID
Posted By: cavu
Subject: Check Navaid ID
Date Posted: 13 Jul 2015 at 7:37pm
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Short flight from KRME to KSYR. Selected the ILS 28 (freq is 109.9) STODA IAF. As I fly along I activate the approach, 20 miles out. I get the GPS -> VLOC (GPS in green, VLOC in Blue) nav mode and the freq of 109.9 is placed in primary NAV automatically and the ID box displayed next to the freq. As I approach the FAF ZIMBI (straight in from STODA), I get a blue alert, CHECK NAVAID ID. Eventually nav mode just goes to GPS only and the VLOC disappears. Am I doing something wrong? |
Replies:
Posted By: rolfe_tessem
Date Posted: 13 Jul 2015 at 8:59pm
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I have had this happen too, or the switch happened at the very last moment. I'm not sure how to alleviate it, other than switching manually at a certain point if the box hasn't done it for you. I believe it won't switch if it hasn't correctly decoded the morse code identifier, and that is the problem as some of these are really weak. At my local airport where I do practice approaches, they use the same frequency for both directions on the ILS, which can also be a problem I think... |
Posted By: oskrypuch
Date Posted: 14 Jul 2015 at 2:27am
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Cavu, Did you do an aural check of the LOC ID? As Rolfe mentions, a weak or incorrect nav id (other direction ILS/LOC) will cause this. * Orest |
Posted By: cavu
Date Posted: 14 Jul 2015 at 9:36am
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I thought the ID flag in the NAV freq box signifies that the ID has been verified??? If not, what is its purpose? Also the active freq switch occurs as soon as I activate the approach some 20 miles out. So all the criteria is met, straight in to FAF, NAV id flag showing, ILS activated in FMS (not VTF but to the IAF), approaching FAF. |
Posted By: oskrypuch
Date Posted: 14 Jul 2015 at 9:43am
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No, when the station is identified, its actual identifier will appear in that box. ID just means it is receiving something, and trying, I think. The IFD seems to demand a higher level of confidence before it will show the ID. My SL30 usually shows the identifier sooner. * Orest |
Posted By: roltman
Date Posted: 14 Jul 2015 at 10:01am
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I had some issues where there was a faint "tapping" sound bleeding into the nav audio from my strobes firing. The signal was fine for the needles/AP and the approach, but the IFD540 decoding was sporadic at best. I put new Whelen LED strobes in place of the old flash tubes and the problems solved. I guess, I would start by listening to the Nav audio and see if there's any odd sounds on the channel that could interrupt the automated decoding. |
Posted By: oskrypuch
Date Posted: 14 Jul 2015 at 10:09am
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Pg 6-11 of PG "...the frequency tuned by the nav radio matches the frequency of the approach navaid and the identifier decoded by the nav radio does not match the identifier of the approach navaid." KSYR uses 109.9 for both 28 & 10. The IFD was trying to warn you the ID did not match the approach plate. If this was a simulated approach, sometimes they don't flip the LOC in time. If this was an IFR flight, someone really goofed. Either way an aural check would have caught it as well. * Orest |
Posted By: cavu
Date Posted: 14 Jul 2015 at 1:55pm
| So it should show iSYR when ID'd? How does the 540 know that I have manually checked the ID for the ILS? As the 540 switched from GPS -> VLOC to GPS when I got to the FAF automatically, how do I suppress that? |
Posted By: oskrypuch
Date Posted: 14 Jul 2015 at 5:04pm
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If the freq and ID match it accepts that it is correct, and switches. If you prefer it to not switch when conditions are met, that is one of the user settings. * Orest |
Posted By: roltman
Date Posted: 14 Jul 2015 at 5:49pm
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I think this || the subject so I'll post it. Is there an adjustment for the VLOC switching to make it happen earlier? I flew into KMEM yesterday and got a 15deg cut at the LOC. The ILS was ID'd and armed to switch on the IFD540. I had my Stec 60-2 in HDG mode with NAV armed. Yes I was curious specifically how this simple transition was going to take place and how my AP was going to react, so I left it all alone as it was severe clear. The GPS->VLOC transition was so late my 60-2 couldn't capture the LOC and it shot through the LOC prior to it coming back aggressively which cause it to shoot through and not capture the GS. At a minimum for my 60-2 this GPS->VLOC transition needs to happen sooner for it to be fully automated. |
Posted By: oskrypuch
Date Posted: 14 Jul 2015 at 6:04pm
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You can manually force the switch any time, just turn the knob on the 540. But, I would not suggest you do that, the intercept will be awkward. If is better to leave your ap in hdg mode, then once you are LOC alive, switch to GPSS mode. You will get a perfect intercept. Once intercepted and aligned you can switch to appr mode and vloc at you leisure. Note that GPSS mode will not provide guidance past the faf on an approach that is not allowed as an overlay and is not a primary RNav approach The best solution is IFD540 hdg -> vloc mode, unfortunately that mode was pulled during the cert run up, hopefully it makes a reappearance. * Orest |
Posted By: cavu
Date Posted: 14 Jul 2015 at 6:08pm
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I'll repost this because no one answered the questions. The Pilot Guide gives precious little information. So it should show iSYR when ID'd? How does the 540 know that I have manually checked the ID for the ILS? As the 540 switches automatically from GPS -> VLOC to GPS (as no VOR/ILS has been ID'd) when I get to the FAF, how do I suppress that? And I agree, it does seem to take the aircraft in pretty close before switching. Is it waiting to see the GS active? I can't get the iPad simulator to ever ID the ILS. Does that sound right?
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Posted By: rolfe_tessem
Date Posted: 14 Jul 2015 at 10:07pm
| On my last practice approach, I was vectored to intercept the LOC pretty close in and the 540 didn't switch until the last possible moment -- right at glideslope intercept -- which was about 10 seconds after wings level. That seems unacceptable. Should I have switched manually earlier when I realized that it wasn't going to do it automatically? I guess to, but I guess the question is when? |
Posted By: DavidBunin
Date Posted: 15 Jul 2015 at 9:46am
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Yes, I think so. The "ID" on the right side is controlled from the Audio tab on the AUX page. You turn off the ID mode to more clearly hear to a HIWAS or other voice signals over the VOR frequency.
I think you're telling the unit that you have identified the morse code audibly when you clear (CLR) that cyan message.
Turn the mode knob one click to the right.
I haven't had much luck with VORs or ILSs in the simulator. |
So it should show iSYR when ID'd? Posted By: cavu
Date Posted: 15 Jul 2015 at 11:28am
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Thanks Dave, I'll have to check in the airplane, as clearing the Check Nav ID alert does not auto switch to VLOC. Or does the autoswitch only occur when the IFD auto senses the ID? Wouldn't I be able to hear HIWAS by using the audio panel controls? I have the PMA 6000 |
Posted By: AviJake
Date Posted: 15 Jul 2015 at 12:38pm
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I agree with Dave's answers with the following editorial adds: 1. Yes, if you see the identifier decoded to the proper characters then the system has a good lock on the VHF signal. 2. The IFD540 does not know if you've manually checked the identifier. The 540 just provides an aid for you as you "Tune-Identify-Monitor". I put this part in the "Identify" category. As a side bar, the IFD540 will auto tune for you, it will identify the signal for you by decoding the Morse Code and it will monitor for you by presenting a CAS message if something goes awry. I consider all of those aids to the pilot but it's still the pilot's responsibility to T-I-M. 3. You can suppress the auto transition from GPS to VLOC if you want to via the "GPS --> VLOC Capture" selection in the User Options page. Not sure why you'd want to turn that off personally but you certainly can if you want to. 4. Ipad sim will not ID the (non-existent) nav freqs for you. Just a limitation of the sim. BTW, I just added some more text to the pilot guides reference the auto-tuning behavior. Here is a snippet from that new text: Auto-VLOC tuning is a user option which enables the automatic tuning of the active nav frequency slot to follow the governing navaid in the flight plan. If the active leg is part of a VHF-based approach, the FMS will auto-tune the navaid that defines the final approach. If the active leg is not part of a VHF-based approach, and if the active leg has a recommended navaid in the database, the FMS will auto-tune that navaid. Otherwise, from the active leg, the FMS will look backward through the route and forward through the route for legs with a recommended navaid or that are defined by a navaid, in which case, the FMS auto-tunes the one of those two navaids that is closer to the aircraft. ------------- Steve Jacobson sjacobson@avidyne.com |
Posted By: cavu
Date Posted: 15 Jul 2015 at 1:33pm
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Hi Mr. Jacobson, The iPad is set up with GPS-VLOC Capture set to AUTO. When the above scenario is entered and the aircraft approaches the FAF, the GPS-> VLOC goes to GPS not VLOC. Is this because there is no actual VOR in the simulation, so it doesn't navigate by it? I can force the nav mode to VLOC by turning the upper right knob and it seems to navigate on the path. It stays yellow. But the aircraft is navigated by GPS (does the missed, enters hold etc). This is a little confusing. The iPad is basically simulating a case where you have the correct frequency entered but no VOR signal is received (off the air), thus it stays yellow if manually selected (corresponding flag on HSI) or if in auto capture, reverts to GPS. My question is, if in the real world, the ILS is in fact operating, the correct frequency is entered but the auto identifier is not identifying the ILS morse code, what will happen? Will the GPS ->VLOC go to VLOC and turn green or stay yellow due to auto identifier not happy with morse code. I've read your new text "If the active leg..." and I'm having a hard time following it. Perhaps an example? |
Posted By: AviJake
Date Posted: 15 Jul 2015 at 2:06pm
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Yes, you're descriptions for iPad sim and the actual hardware are all accurate. To answer your question on "what will happen?", I've pasted in another snippet from the existing pilot guide under the "Armed vs Engaged/Active Indications" section that hopefully will help: The active IFD nav mode is displayed in green along the right edge of the top data strip. The armed IFD nav mode, if there is one, is displayed in blue along that same top strip. When there is an armed state, the nav source is depicted per the image below. As the armed mode is captured, the previously active nav mode lamp will extinguish and the previously armed state will turn green and begin to flash. The flashing should last approximately 5 seconds and the nav mode will not actually change until the flashing stops and the indication becomes a solid lamp.To trigger the transition from armed VLOC to active VLOC, all of the following capture criteria must be met: · The tuned frequency in the nav radio matches that of the approach navaid; · The Morse code decoded by the tuned nav radio matches the identifier of the approach navaid; · The aircraft track is within 15 degrees of the final approach course; · The course to the active waypoint is within 45 degrees of the final approach course; · The radio deviations are at most 50% of full scale for 5 consecutive seconds; · The active leg is part of the approach up to and including the final approach fix. ------------- Steve Jacobson sjacobson@avidyne.com |
Posted By: cavu
Date Posted: 15 Jul 2015 at 2:59pm
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Yes, I understand all that. Suppose I meet all the criteria listed except the morse code decode does not match (poor reception, noise etc). Is it possible to use the Nav mode VLOC without the Morse Code decoder completing its task, i.e. I manually verify the correct frequency? |
Posted By: AviJake
Date Posted: 15 Jul 2015 at 3:16pm
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Yes, that's definitely possible and works fine for me whenever I've tried that. As long as the radio has picked up the signal in sufficient strength to provide deviation data, it will do just that. The issue is the signal strength required to decode and display the identifier and therefore auto transition the nav mode. As a note, the IFD does take its sweet time to decode the identifier. It waits for a very strong (I didn't take the time to look up and quantify the definition of "very strong") signal and goes through a few cycles before it presents the identifier. We also have a CAS message "Check Navaid Identifier" that will be presented for several reasons. One reason is all of the above transition criteria have been met EXCEPT for the decoding criteria. I've used that myself to push the nav source to VLOC - I get the message, I quickly check the nav freq to make sure it's right, then manually push to VLOC. ------------- Steve Jacobson sjacobson@avidyne.com |
Posted By: rolfe_tessem
Date Posted: 15 Jul 2015 at 3:23pm
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Steve, I think the problem is the criteria to be within 15 degrees of the final approach course. Given that most controllers aim for something like a 45 degree intercept, a late turn on is going to leave you wondering whether you're going to get the GS or not. Is there any chance that criteria can be widened? Rolfe |
Posted By: cavu
Date Posted: 15 Jul 2015 at 3:25pm
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That makes sense. Thanks The last issue, again on iPad not sure if on real airplane, I have VLOC in yellow (manually forced it) but the airplane is following the GPS track to the missed and hold.
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Posted By: AviJake
Date Posted: 15 Jul 2015 at 3:26pm
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Yes Rolfe, we will evaluate the idea. ------------- Steve Jacobson sjacobson@avidyne.com |
Posted By: AviJake
Date Posted: 15 Jul 2015 at 3:27pm
I can't remember for sure. I'll have to look that up when I get a minute and post an update. ------------- Steve Jacobson sjacobson@avidyne.com |
Posted By: cavu
Date Posted: 15 Jul 2015 at 3:40pm
| Roger that. See you at Oshkosh |
Posted By: cavu
Date Posted: 02 Aug 2015 at 9:10pm
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Steve, Did you get a chance to look this up?
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Posted By: AviJake
Date Posted: 09 Aug 2015 at 10:12am
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No I didn't but it's back on the list for this week. ------------- Steve Jacobson sjacobson@avidyne.com |
Posted By: oskrypuch
Date Posted: 09 Aug 2015 at 10:39am
FWIW, a proper LOC intercept is 30deg max, 20deg max if close to the approach gate. * Orest |
Posted By: Kentucky Captain
Date Posted: 14 Aug 2015 at 5:09am
Actually a "legal" intercept for controllers is At least 2 miles outside the approach gate at up to 30 degrees unless one of the following exists: 1. When the reported ceiling is at least 500 feet above the MVA/MIA and the visibility is at least 3 miles (report may be a PIREP if no weather is reported for the airport), aircraft may be vectored to intercept the final approach course closer than 2 miles outside the approach gate at up to 20 degrees but no closer than the approach gate. The approach gate is 1 mile outside the final approach fix. 2. If specifically requested by the pilot, aircraft may be vectored to intercept the final approach course inside the approach gate but no closer than the final approach fix. Having said all of that I was a controller in a fairly busy Tracon for 27 years until they put me out to pasture at the ancient and mandatory retirement age of 56 last year and I have seen some really bad turn ons over the years. If you find yourself in something that you don't feel comfortable with I wouldn't hesitate to ask to be re-sequenced or even to ask for an extended final. You might get vectored around a little but that's better than getting turned on at the marker in low IMC. |
Posted By: rolfe_tessem
Date Posted: 14 Aug 2015 at 1:33pm
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I would be delighted to get 30 degree intercepts even most of the time :-). The point was, the IFD needs to be within 15 degrees of the final approach course to automatically switch to VLOC. That is inconsistent with real-world intercepts, be they 25 degrees, 30 degrees, or whatever... Rolfe
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Posted By: wookie
Date Posted: 20 Aug 2015 at 11:52pm
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Going into Leesburg VA, unable to find the traffic that seemed to be
running ahead with other targets confusing the pix then learning that
that day the Saberliner and 172 collided in San Diego caused me to think
about the dedicated traffic page again. Lots of cool ideas offered, but few as important than the dedicated traffic page! BH ------------- BH |
Posted By: DavidBunin
Date Posted: 21 Aug 2015 at 8:22am
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Are you not using the dedicated traffic thumbnail data block? That serves the purpose well enough for me. David Bunin |
Posted By: wookie
Date Posted: 21 Aug 2015 at 8:53am
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On the subject day, it was so full of data I couldn't make sense of it. BH ------------- BH |
Posted By: DavidBunin
Date Posted: 21 Aug 2015 at 3:48pm
| LOL. If it's that busy, you should probably be looking OUTSIDE anyway! :) |
Posted By: brou0040
Date Posted: 21 Aug 2015 at 8:23pm
A quick look at a clear display of the traffic can optimize your heads up time. Has there been any studies done about how long it takes for pilots to see other traffic? With no radio, with self reporting, with ATC, with a traffic system? I can't imagine anybody would suggest that you are worse off with a traffic system than just looking outside the entire time.
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Posted By: wookie
Date Posted: 21 Aug 2015 at 10:03pm
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The traffic was ahead of me apparently on the southbound GPS... as I went down it, it appeared that he went underneath and behind me. Made me crazy that I couldn't find him. The poor display did not help. When I'm near the airport, nothing matters except traffic. I want the full screen display with nothing else on it!! BH ------------- BH |
Posted By: MysticCobra
Date Posted: 12 Sep 2015 at 6:38am
Did this ever get answered?
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Posted By: MysticCobra
Date Posted: 12 Sep 2015 at 6:47am
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I had the situation described by the OP yesterday. Flew an ILS, was in GPS > VLOC mode, thought I'd met all the criteria (including the IFD auto-recognizing the ILS morse code, but maybe I just misinterpreted the display) and was wondering when it was going to switch to VLOC when I unexpectedly got the "CHECK NAVAID ID" (which I acknowledged). The SL30 had already auto-detected the morse ID and was giving good LOC/GS information. I continued flying to see if the IFD would decode the morse in time and auto-swap to VLOC. Nope...it eventually reverted to GPS mode and I ended up flying the approach using the SL30's CDI. Kind of disappointing when the old technology seems to outperform the new. Why was the SL30 able to decode the morse, but the IFD was not?
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Posted By: oskrypuch
Date Posted: 12 Sep 2015 at 9:39am
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My SL30 will usually come up with the NavID first, I think it is less fussy on the signal validity, the penalty then being that sometimes it may get it wrong. * Orest |
Posted By: wookie
Date Posted: 12 Sep 2015 at 10:05am
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I do find that it sometimes misses the ID even when the morse is pretty clear. BH ------------- BH |
Posted By: n7ifr
Date Posted: 12 Sep 2015 at 10:15am
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I also consistently have the sam experience with the SL30 capturing the Morse very quickly. Tom Wolf
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