Green vs Magenta needle on VOR Approach

Shiftace

Shiftace

s***posting with decency. trolling with integrity.
Trying to get some clarification on this.

Some DPEs are ok with magenta needle being used for the approach as long as the VOR is tuned in and the bearing pointer is up. AIM 1-2-3 confirms this.

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However, AC 90-108 has some conflicting information.

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I teach my students magenta needle till before the FAF. Then green needles.

How are you teaching?
 
I don’t think anywhere outside GA flies VOR approaches off the actual VOR anymore. So from a practical perspective if the student is going for anything other than a GA PPL long term I would get them used to using FMS/GPS overlay.
 
Is it the wording of 8-b you're concerned with?

Because in the scenario you describe, you're not substituting, you're enhancing. You're still getting primary guidance from the NAVAID and using GPS to enhance SA. The NAVAID still has to be working - the point of the AC is that if it's not working, then it doesn't matter what RNAV SA-augmenting technique you want to do...you can't do it because the primary NAVAID isn't working.

If you switch to green needles on the FMS from the FAF in, that's fine - we always did it that way at a large 141 and neither the DPEs we occasionally used nor the FSDO - who oversaw our self-examining program with a fine toothed comb - had any issue with this. But only if the LOC/GS was working. If it wasn't, you couldn't fake it with RNAV.
 
I'm also not seeing a difference between the AC and the AIM language. I teach that you can do a "VOR" approach using the GPS on nav one as long as you have the VOR tuned up on nav two. The weird thing is if the VOR is on the field but slightly offset from the runway and the GPS final lines up straight in on the runway, you are going to notice a difference between the CDI needles. This would be normal but could be pretty extreme on some approaches.
 
Shiftace said:
I teach my students magenta needle till before the FAF. Then green needles.

How are you teaching?
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I don't think the information is conflicting - you still have to monitor the underlying navaid from the FAF onwards. I think the confusing part might be in AIM 1-2-3 c.4 Note 5 "Use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure based on a VOR, TACAN or NDB signal, is allowable."

While Note 5 says it is allowable to use RNAV on the final approach segment, but you still need monitor the VOR as well. The way I have my avionics installed, the HSI only shows GPS. The VOR/LOC is a separate unit, that only shows that. I like it that way, because there is no possible way you can select the wrong CDI source. So, my G5 is going to show a magenta needle on every approach. Still need to monitor the VOR/LOC on the nav radio's CDI, but the GPS based HSI is much easier to fly, shows wind and ground track, etc. I also like that more, because I'm almost never using VLOC in real life, and its more redundant being having separate avionics if I ever need that.

Garmin avionics will only show one course CDI at one time as best as I can tell, but will let you add bearing pointers. So you could have a GPS CDI source and a bearing pointer showing the VOR radial you are on. I don't really like this, which is why I have a totally separate CDI for the nav radio. But I do understand it to mean that the bearing pointer derived from a nav radio source satisfies "monitoring" the station. In the case of a localizer, you need to see the raw data (per Note 2), so for most Garmin installations, this must be green needle.

I though my VOR was broken for about a week, until I realized that all 4 VORs I had tried were out of service. Which is about how useful relying on VORs has become.

I think the guidance here could be made more clear by just saying "If you have RNAV, you are in nearly every circumstance better off using the RNAV procedure!"
 
DE727UPS said:
I'm also not seeing a difference between the AC and the AIM language. I teach that you can do a "VOR" approach using the GPS on nav one as long as you have the VOR tuned up on nav two. The weird thing is if the VOR is on the field but slightly offset from the runway and the GPS final lines up straight in on the runway, you are going to notice a difference between the CDI needles. This would be normal but could be pretty extreme on some approaches.
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At least in my Garmin GPS, when you load a VOR approach, it warns you "NOT APPROVED FOR GPS. GPS guidance is for monitoring only. Activate approach?" But it totally points at the station, and agrees with my nav CDI, no offsets or anything like that.
 
I teach green needles for ground based navaid approaches, magenta needles for the GPS based ones. Similarly, match the RMI source with the CDI source. Keeps pilots knowing the back to basics with the green needles, and doesn’t cause reliance on just following a magenta line only.
 
MikeD said:
I teach green needles for ground based navaid approaches, magenta needles for the GPS based ones. Similarly, match the bearing pointer source with the CDI source. Keeps pilots knowing the back to basics with the green needles, and doesn’t cause reliance on just following a magenta line only.
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Generally I agree with this. However, the SA you can gain by blending on some NP approaches should not be overlooked.
 
Maximilian_Jenius said:
So 121 doesn't use VOR's as fixes anymore? Just waypoints?
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I often put a VOR bearing pointer up to something generally ahead of the airplane when doing transcons. Literally every captain I’ve flown with has been like “wtf are you doing”. I even found a functionality on some of the max’s that our books don’t mention and no one has been able to explain to me.
 
killbilly said:
Generally I agree with this. However, the SA you can gain by blending on some NP approaches should not be overlooked.
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See too many pilots overlook what their various info is being sourced by, or what it is referencing, when they are selected to different info sourcing. Just last week, giving a VOR/DME with 10 DME arc. Pilot has got the RMI on GPS and it’s pointing directly to the fix at the arc-to-final waypoint, and she’s twisting/turning 10 with the CDI sourced to the VOR. The RMI is doing nothing productive for her, for how it’s set and for where on the approach she is.

Procedurally, it’s not wrong. But it’s an inefficient use of the nav sources in front of you, which is essentially two nav abilities on the HSI from the VOR. If she’d had the RMI in Nav, that would make the arc 100 times easier, and she would’ve been able to just set the course setting to the inbound course and never have to change it again. Would be able to see exactly when to expect the CDI to come alive, as the RMI head dropped to the inbound course. Place the RMI head off the wing, and ahead or behind it if outside/inside the arc, as needed.

Again, not procedurally wrong, but creating a lot of unnecessary work for herself in the cockpit, when the objective is to keep workload down in IMC by working ahead and doing things efficiently. That’s where some techniques work better than others, even though both are procedurally correct.

When you come across someone who thinks ahead in radial to arc and arc to radial planning when flying raw data, it’s a gem to see.
 
Makes you wonder about her background. Maybe she has never used an RMI. A G1000 has a bearing pointer but it's not like having a stand alone RMI like I'm guessing you are talking about. If she's going old skool on an arc that's probably all she knows.
 
DE727UPS said:
Makes you wonder about her background. Maybe she has never used an RMI. A G1000 has a bearing pointer but it's not like having a stand alone RMI like I'm guessing you are talking about. If she's going old skool on an arc that's probably all she knows.
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Yeah, I’m using the term bearing pointer and RMI interchangeably. In terms of not knowing how they work and how to make them work for you. She’d initially learned the basics, as was being demonstrated, but has been doing all magenta line for a long time and was trying to get some back to basics going. Good thing is, the motivation and desire to learn and re-learn was very high and very positive. So that’s really nice to see.
 
MikeD said:
Procedurally, it’s not wrong. But it’s an inefficient use of the nav sources in front of you, which is essentially two nav abilities on the HSI from the VOR.
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Which radios/navigators/HSI were installed? This stuff has gone from "not standardized but mostly the same" to "wild west of the AP only works on #2 nav source, but only when HSI is in GPS, but not when..." And it's usually buried in an 800 page install manual, and not the pilot supplement :(
 
Roger Roger said:
I often put a VOR bearing pointer up to something generally ahead of the airplane when doing transcons. Literally every captain I’ve flown with has been like “wtf are you doing”. I even found a functionality on some of the max’s that our books don’t mention and no one has been able to explain to me.
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You talking about the endless dashed green radial line it will draw out and you can't get rid of?
 
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