Flying the Magenta Line

airdale

airdale

Pattern Altitude
Joined
Dec 30, 2007
Messages
1,840
Display Name
Display name:
airdale
I just read a couple of posts this morning talking about flying the magenta line or the equivalent, flying the little airplane around a georeferenced plate.

I have always considered this to be a sign of sloppy piloting. First, the accuracy of flying the magenta line depends on the scale setting of the moving map display. This means you can be far off course and looking good. Second, it creates reliance on a single gadget and over time IMHO weakens the pilot's ability to use the rest of the panel to navigate.

My favorite GPS display is the Nav 1 screen on the G430. DTK, BRG, TRK, and a CDI and I am a happy guy. To get the same on a 530 you get a lot of other clutter and on the G1000 the numbers are scattered between the two screens. When flying a G430 I can easily go a whole flight without looking at the map screen. Same-o on the G1000 -- when a check pilot makes the MFD map go away on an instrument approach or in a hold I hardly notice.

Others' thoughts?
 
I have never heard of anyone navigating solely by flying the magenta line on a GPS. Every plane I have flown with 430/530 has had NAV 1 coupled to the GPS unit so the magenta line is referenced on the #1 VOR head/HSI etc. One of our Lears has a 430w and we use it for VNAV mostly.
 
I have never heard of anyone navigating solely by flying the magenta line on a GPS.
Click to expand...
I fly a fair number of $100 hamburger runs. When I am in the right seat I see it frequently when an autopilot is not present or not in use. When flying as safety pilot I frequently see people flying holds using the moving map. What stimulated my question was a mention here (another forum) by a student pilot of "flying the magenta line" on an approach.

I would hope that someone flying Lears would not be doing this. :)
 
Actually, while I have my GPS coupled to the HSI, I more often than not watch the indicator (not necessarily) on the GPS itself for the cross track error which is much more sensitive than the CDI needle. This isn't so much because I want to fly within a hundredth of a mile of the courseline, but you can see if you're trending left or right (or away or towards) the course.
 
I wouldn't recommend solely using the magenta line, but it is a very useful tool to have in conjunction with CDI. The advantage of the Magenta Line (aka Moving Map) is that it gives you a much better overall positional SA. While the CDI can give you a more accurate picture of cross track error, the moving map allows you to instantly see where you are in relation other navaids or hazards. If you incorrectly set up your GPS track or approach, it may not be readily apparent as viewed solely on the CDI - you could easily fly into a mountain following the CDI with the needle centered. Cross checking the CDI with the moving map can help identify potential issues like that.

In short, I wouldn't ignore the moving map or geo-referenced plates, but like anything else, I wouldn't want to rely on those alone.
 
I have a portable 496, so no coupled HSI. I fly the heading indicated by the GPS and set the heading bug on the DG, which is calibrated to my compass. I guess that is sort of flying the magenta line. I am VFR only though, so I can also look out the window and point to some landmark far ahead (which I do, because it is easier than flying the bug).
 
I am confused about the question, the magenta line isn't a form of navigation only a graphical representation of desired course according to the flight plan?

If someone flying VFR wants to use it and try to hand fly along it, whatever. It's probably still more accurate than someone building a flightplan with compass headings and estimated winds.

The other question is how many pilots can hold the TRK and DTK within 1 degree for any period of time hand flying? That might be the place to start if we're looking for accuracy.
 
I use the magenta line as a guideline but I don't strictly try to "fly it." I do the same as John221us and fly by the heading bug and/or visual targets when VFR.
 
airdale said:
I fly a fair number of $100 hamburger runs. When I am in the right seat I see it frequently when an autopilot is not present or not in use. When flying as safety pilot I frequently see people flying holds using the moving map. What stimulated my question was a mention here (another forum) by a student pilot of "flying the magenta line" on an approach.

I would hope that someone flying Lears would not be doing this. :)
Click to expand...

Well when we are in RNAV mode we don't have much of a choice but to fly a hold based on the GPS, whether its a 430, a 530 or by the FMS. If I feel like it, I will back it up on NAV 2 but it isn't really necessary. I guess I can see both sides of the coin. Flying the magenta line is arguably what all 121 operators do. As well as anyone flying a modern aircraft under 91 or 135. Are they looking at the physical screen of the GPS or is it transposed on the PFD or MFD? Maybe both. Hell, whether its a magenta line, or centering the CDI and flying that line to a NAVAID, what in reality is the difference? In fact the magenta line will be more accurate.
 
I will add, that when I am flying a Citabria, the last thing I want to stare at is a magenta line. But when you start flying higher and faster, the magenta line or equivalent, is actually how you fly. We don't have a whole lot of glass in our Lears, but in glass cockpit aircraft, that magenta line is represented on a huge screen, and that is how you are flying the aircraft.
 
Magenta line == one tool for situational awareness. HSI (or equivalent on GPS NAV page) == course guidance. When flying holds I certainly use the "magenta racetrack" to help in estimating how much drift correction I need, and to prevent disorientation from a brain fart, but only the HSI has the accuracy to tell me if I'm on the protected side.

I also keep the numeric TRK readout in my scan and find it's the quickest way to know if I need to make a course correction before the needle starts to move.
 
Airdale You are clearly a superior aviator. I commend you.
 
Last edited:
Inverted said:
Well when we are in RNAV mode we don't have much of a choice but to fly a hold based on the GPS, whether its a 430, a 530 or by the FMS. If I feel like it, I will back it up on NAV 2 but it isn't really necessary. I guess I can see both sides of the coin. Flying the magenta line is arguably what all 121 operators do. As well as anyone flying a modern aircraft under 91 or 135. Are they looking at the physical screen of the GPS or is it transposed on the PFD or MFD? Maybe both. Hell, whether its a magenta line, or centering the CDI and flying that line to a NAVAID, what in reality is the difference? In fact the magenta line will be more accurate.
Click to expand...
If you could pick only one thing to look at would it be the HSI or the MFD? I think that's what people are getting at. I think of "flying the magenta line" as trying to steer by using the little airplane on the MFD.
 
Coupled with the cross-track guidance, it can be pretty darn accurate. I don't have a big problem which tool people choose to use, as long as their head isn't stuck in the cockpit. You can argue the magenta line helps them know where they are quickly and precisely rather than having them staring at a chart, deciphering VOR frequencies, tuning and identifying, then trying to triangulate their positions continually while en route.
 
This thread is pretty funny. As if there was any difference between the source reference of the magenta line on the GPS and the needle on the CDI.

Too funny.
 
LDJones said:
Coupled with the cross-track guidance, it can be pretty darn accurate. I don't have a big problem which tool people choose to use, as long as their head isn't stuck in the cockpit. You can argue the magenta line helps them know where they are quickly and precisely rather than having them staring at a chart, deciphering VOR frequencies, tuning and identifying, then trying to triangulate their positions continually while en route.
Click to expand...

It definately helps with avoiding airspace issues.
 
docmirror said:
This thread is pretty funny. As if there was any difference between the source reference of the magenta line on the GPS and the needle on the CDI.

Too funny.
Click to expand...
There is no source difference, but there is definitely a difference in technique based on whether someone is primarily looking at the needles as opposed to steering the airplane symbol.
 
Everskyward said:
There is no source difference, but there is definitely a difference in technique based on whether someone is primarily looking at the needles as opposed to steering the airplane symbol.
Click to expand...

No shyte Sherlock. Which is why I said it's 'too funny'.

So, if the plane in the little display shows a deviation to the left of the magenta line, and the CDI deflects to the right of center, you're saying the technique to correct that is different, based on which instrument I look at? :yes: :no:
 
docmirror said:
No shyte Sherlock. Which is why I said it's 'too funny'.

So, if the plane in the little display shows a deviation to the left of the magenta line, and the CDI deflects to the right of center, you're saying the technique to correct that is different, based on which instrument I look at? :yes: :no:
Click to expand...
You will never get the cross track precision with the moving map that you get with the CDI....but you knew that because your are so smart.
 
docmirror said:
So, if the plane in the little display shows a deviation to the left of the magenta line, and the CDI deflects to the right of center, you're saying the technique to correct that is different, based on which instrument I look at? :yes: :no:
Click to expand...
Yes. Personally I think it's much less accurate to "fly" the airplane symbol than to fly the needles.
 
Now, correct me if I have this wrong, but with a keystroke or two, can't one set up a small bar type CDI on the 430? I know I can do it on my little POS GPS display, and I would think that the G430 would offer this legacy utility as well?
 
Fearless Tower said:
You will never get the cross track precision with the moving map that you get with the CDI....but you knew that because your are so smart.
Click to expand...

Ah - I see, the analog CDI display is more precise than the digital G430. My smartness meter is definitely swinging to the gooderer side.
 
I enjoy pilotage with a touch of dr but in the rare instances when I am navigating by GPS (ex, trying to beat the darkness getting the Luscombe home from a long xc that is running late - no lights on aircraft or home field), I tend to keep an eye on the bearing vs. track numbers rather than the magenta line.
 
docmirror said:
Ah - I see, the analog CDI display is more precise than the digital G430. My smartness meter is definitely swinging to the gooderer side.
Click to expand...
No one said that.

Any CDI display whether on the Garmin unit itself or a separate CDI dispaly will be more accurate than the airplane on the moving map. Analog or digital has nothing to do with it.
 
pre·ci·sion (pr-szhn)
n.
1. The state or quality of being precise;
 
Fearless Tower said:
No one said that.

Any CDI display whether on the Garmin unit itself or a separate CDI dispaly will be more accurate than the airplane on the moving map. Analog or digital has nothing to do with it.
Click to expand...
Very true. Even on the 4nm scale, my GMX-200 often shows the little airplane right on the magenta line while the CDI is half scale deflected.( This is in enroute mode; I've never compared them while in terminal or approach modes.)
 
Bummer, my cheap, ancient GPS goes down to 0.1NM scale. I defy any CDI to beat that.
 
docmirror said:
Bummer, my cheap, ancient GPS goes down to 0.1NM scale. I defy any CDI to beat that.
Click to expand...

Yeah, but zoomed in that far, you might as well be on a CDI page, the moving map is not adding any situational awareness. I like to keep the map zoomed out so I can see airspace issues coming up and use track/bearing numbers to fine-tune my compass course.
 
Well, I wouldn't want anyone to suffer carpal tunnel due to clicking between 20 and 2NM scale on the box.

I haven't had a CDI in a plane for 10 years and don't miss it one bit.

I'm done here, you analog experts do it anyway that floats your boat, or tunes your piano.

CDI better than moving map display. ooooooooooooooookkkkkkkkkkaaaaaaaaaayyyyyyyyyy
 
docmirror said:
I haven't had a CDI in a plane for 10 years and don't miss it one bit.
Click to expand...
I was going to suggest you try to fly a GPS approach only using the moving map and not the CDI, but since you don't have a CDI I guess you don't fly IFR which is what we mostly talking about. Also, since you don't have a CDI you can't really compare the accuracies. We are not talking about accuracy of input but the human factor of how it's easier and more precise to follow the needle rather than steer the symbolic airplane.
 
docmirror said:
I'm done here, you analog experts do it anyway that floats your boat, or tunes your piano.
Click to expand...


35ke38.jpg
 
Everskyward said:
If you could pick only one thing to look at would it be the HSI or the MFD? I think that's what people are getting at. I think of "flying the magenta line" as trying to steer by using the little airplane on the MFD.
Click to expand...

Well, I am used to looking at an HSI so that is where my eyes go right now. But good luck finding an HSI in a glass cockpit.
 
Inverted said:
But good luck finding an HSI in a glass cockpit.
Click to expand...
I fly with a glass cockpit and set the display to HSI. So do the other people I fly with. Even if you set the display to ARC you still get the top half of the needles.
 
docmirror said:
This thread is pretty funny. As if there was any difference between the source reference of the magenta line on the GPS and the needle on the CDI.

Too funny.
Click to expand...

This is what I was thinking too. In the end it is a navigational reference line. Whether that is from a VOR, NDB or GPS. It is the same intercepting and tracking technique in its simplicity.
 
Everskyward said:
I fly with a glass cockpit and set the display to HSI. So do the other people I fly with. Even if you set the display to ARC you still get the top half of the needles.
Click to expand...
That comment had me scratching my head too... I have seen a lot of glass with HSI displays.
 
Fearless Tower said:
35ke38.jpg
Click to expand...

Well,,,, since I'm an EE, and I've been building circuits for - oh, I would say 25 years I have a decent idea of what it means.

http://www.mikeg.net/hobbies/aviation/avionics/maintenance/King KI-204 Maintenance.pdf

(Page 5-2 & 3, page 5-5 table 5-2 for those playing along at home. Gosh, is that -- could that -- maybe it's a analog frequency generator supplying the differential signals to the CDI! )

However, an interesting note is that there are now digital CDI displays, even with a GS built in. Neato! maybe I'll get one.

http://stores.worldavionics.net/-strse-238/INS-422/Detail.bok

Keep shootin' Tex. Eventually you'll hit somethin.
 
Fearless Tower said:
That comment had me scratching my head too... I have seen a lot of glass with HSI displays.
Click to expand...

Our lear has a DHSI similar to this:
5ATI-HSI.gif


What I was meaning, was that a full glass avionics suite might not have a typical HSI. as you can see, even on that HSI, it is flying an airplane on a magenta line ;)
 
You must log in or register to reply here.
Back
Top