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Magnetic Heading or GPS Track :)

R

RV8R999

Well Known Member
I've enjoyed the Altimeter vs GPS Altitude thread so much thought we could continue the discussion...

When ATC gives you a heading do you fly a magnetic compass (whatever the source) or a GPS track?

Which do you believe ATC really needs you to do? What is the goal of the heading change? Which method best achieves the goal given the tools ATC has available?

I fly GPS TRK.

tkatc?
 
ATC is set up to compensate for current wind conditions. Typically they are asking for a magnetic heading, not ground track.
 
Mel is absolutely correct, plus not every one has GPS track so they can't give you one type of headind another type to a different aircraft.

The giving heading is magnatic.
 
That's interesting. I'd have thought that, ideally, they have a direction in mind like a line over the ground, irrespective of magnetic heading. If there's a strong crosswind, your magnetic heading will be far different from your ground track (duh).

Given how inaccurate winds aloft data usually are, it surprises me that they have that "built into" their system. :D
 
When told "turn left to heading 340 clear for TO" that's what I do, however when told "maintain runway heading, clear for TO" I assumed they want me on the extended runway centerline, which may or may not be runway heading, until cleared on course.

Paul Danclovic
Jamestown NC
RV-8A N181SB
 
This was all put in place long befor GPS ground track was common. The controllers compensate for the wind and if you fly track, you are going to mess with their plan...
 
Ha! I knew it :)

I started using track when flying in strong crosswinds and noticed a much reduced incidence of repetitive heading change calls from ATC for traffic or when being vectored to an IAF while flying a heading...ya know the call "RVX turn left 30 deg for traffic", 1 min later, "RVX turn another 10 deg left please". Whevever I fly track they get it right the first time.

Some ATC stations may have good winds, they may not, but what they will never know is the accuracy and currency of your compass calibration which is rendered non-consequential when flying a GPS track. Considering the growing utilization of AHRS with electronic compasses there is no telling the quality of heading info from the folks flying around us.

Track for me when it makes sense...

Oh...there is no question ATC is asking for MAG heading. The question is what do they REALLY WANT...

Now what about Indicated Airspeed and GPS Groundspeed???? :))
 
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When I di my instrument training it was before all this GPS whooy ;)

We flew compass headings and if the wind was blowing us off course, ATC would just give us an adjusted heading.
 
FAR

I always go by the FAR's assuming if the FAA comes to get me and I say that I was doing what the FAR's told me that I would be fine.

I do think there is a bit of a conflict though, I agree with Mel, when the controller gives me a heading...obviously they are telling me where to point the nose, they are accounting for the winds. BUT, FAR's say to use magnetic course when determining VFR cruising altitudes, so you should be the one compensating for wind. Well, what about VFR flight following with a suggested heading while flying VFR cruising altitudes??
 
What they really want is magnetic heading. Typically the controller is aware of the winds and has been told if there are strong winds by the previous controller and they compensate for that. If they keep correcting the heading they are getting acclimated to the current situation. (Or they just want to build in more or less separation from other traffic.)

The turn to final is particularly subject to error because of the speed and type of the aircraft, the winds, and the rate of turn performed by the pilot. Its just like flying...ALL your landings are perfect BUT there is that one occasional wind gust that throws you off. :D

So if you decide to fly a TRACK instead of a heading, you are actually hurting the controller's ability to adjust for wind. He will think that winds are not a factor and issue a similar heading to the next guy, who is flying a HEADING, and the heading issued will be flawed.
 
LAMPSguy said:
Well, what about VFR flight following with a suggested heading while flying VFR cruising altitudes??
Click to expand...

:D:D Don't overthink it. When they issue a heading, they know what they want, and if what they want isn't happening they have RADAR to verify it. Then, they will adjust the heading. (But a decent controller will already be factoring the wind into his issued heading)
 
well I just had a chat with a few of the on-duty controllers and my local international airport and asked this question:

"Do you have accurate wind direction and speed info available at flying altitudes and do you compensate for wind when assigning headings?"

Answer:

"We have access to the wind info but don't usually factor it in unless it is causing a problem and we find ourselves adjusting headings too often or we really want a specific track over the ground then we will TRY to use winds - but they are not very accurate. We don't get too caught up on precision when assigning headings because we can see where you are going and make adjustments as necessary"

My next question:

"So if you don't normally compensate for winds how would you feel if a pilot flew your assigned heading as a GPS track instead"

answer:

"Well, as long as it looks as if he is going where we (he asked the guy next to him the question) want we probably wouldn't even notice or care. Most of the time the heading and track are really close unless the winds are raging and then we will be making lots of adjustments anyway"

Interesting...
 
OTOH

OTOH, back in the days when I was flying for food, I was flying an arrival into SEATAC airport. We were given a heading to fly, but instead, I chose to leave the autopilot in LNAV, which took us right up the standard track for the arrival. There was a hefty crosswind at our altitude.

About 3 miles later, the controller asked if we were flying our assigned heading or not, and we confessed to leaving it in LNAV. With a bit of admonishment in his tone, he reiterated that we were to fly assigned HEADING, and gave us a new heading to fly.

So, I guess when a controller says "heading", they actually MEAN "heading' (Go figure?). If they want us to fly a track, they can say the word "track".

Lesson learned, didn't do it again. Even on maintaining runway HEADING after takeoff.
 
Why would they CARE what your heading is? They don't, they care about your track. The heading thing is now just a historical relic. :D
 
dedgemon said:
Why would they CARE what your heading is?
Click to expand...


Because the controller has the big picture about the traffic he (or she) is handling, and you don't. Standards exist to STANDARDIZE - they use heading for everyone (as mentioned above by actual Air traffic Controllers), and they don't have to figure out who is flying what (heading or track). If you're IFR, then play by the same rules as everyone else. The rules might seem silly, but at least they put us all on the same page.

(And yes, I'd support a change to the standards if they wanted to make everyone fly "Tracks" instead of "Headings". It would make sense. it would also mean that every airplane in the system was required to have on board track guidance - yet another equipment requriement....)
 
Ironflight said:
Because the controller has the big picture about the traffic he (or she) is handling, and you don't. Standards exist to STANDARDIZE - they use heading for everyone (as mentioned above by actual Air traffic Controllers), and they don't have to figure out who is flying what (heading or track). If you're IFR, then play by the same rules as everyone else. The rules might seem silly, but at least they put us all on the same page
Click to expand...

Nicely done. I couldn't agree more.

Let me play Devil's advocate though...how would the controller issue you a track? Fly North? Fly east? Fly direct some obscure waypoint that would take you precious seconds to find and enter?

I haven't even thought about flying a track so I may be green here, but it MUST be harder than flying a heading.
 
I have atc ask my present hdg all the time while on FF. I am assuming that is giving them an idea of the winds aloft at 10.5-13.5 where we travel. So far the greatest difference has been approximately 30 deg with a 60 kt direct xw.

On your second topic: I would use gps ground speed to land into the wind if I lost IAS.
 
Must fly assigned heading!

Hi Everyone,
I'm pretty much a lurker here but felt I might be able to add something useful to this thread.

It is indeed important to fly magnetic heading when assigned a heading. Controllers are most concerned with traffic separation. Especially in the terminal environment (takeoff and landing), the aircraft are all moving in the same air mass. So the controller can give headings to aircraft under his control and know that they will all DRIFT similarly thus aiding his efforts to keep them separate.

Aircraft taking off from closely spaced parallel runways are a good example. Since not every aircraft can instantaneously fly a ground track the controller may assign a departure heading knowing they will all drift with the wind in a predictable manner and not have a conflict. If the aircraft departing 27R flew ground track and the aircraft on 27L few runway heading, a strong south wind could result in loss of separation as the 27L departure drifted north across the path of the 27R departure.

That example is a little contrived (many departures these days have us flying a course) but I used it to illustrate the point.

As another poster said, don't over think this one. When ATC says heading, that's what they want. If they say direct or you're flying a course then by all means compensate for the wind using whatever navigation aids you have available - including GPS track.
 
pauldan181 said:
When told "turn left to heading 340 clear for TO" that's what I do, however when told "maintain runway heading, clear for TO" I assumed they want me on the extended runway centerline, which may or may not be runway heading, until cleared on course.

Paul Danclovic
Jamestown NC
RV-8A N181SB
Click to expand...

Paul, If you are cleared to fly runway heading you should fly the magnetic heading. This became a big issue when the 757/767 started flying. The aircraft default TO mode with the flight director gives you a straight out ground track that keeps you aligned with the runway. Crews were violated for not flying runway heading. In reality you are not going to hear anything about it unless you are at a airport with multiple runways and simo departures. If there is a big crosswind and you fly a track you will get a flight violation when you get too close to the aircraft using the other runway or runways who is correctly flying heading. Standard procedure now at most if not all airlines is to switch the flight director mode to heading right after liftoff if its a runway heading departure.

George
 
Ironflight said:
Because the controller has the big picture about the traffic he (or she) is handling, and you don't. Standards exist to STANDARDIZE - they use heading for everyone (as mentioned above by actual Air traffic Controllers), and they don't have to figure out who is flying what (heading or track). If you're IFR, then play by the same rules as everyone else. The rules might seem silly, but at least they put us all on the same page.

(And yes, I'd support a change to the standards if they wanted to make everyone fly "Tracks" instead of "Headings". It would make sense. it would also mean that every airplane in the system was required to have on board track guidance - yet another equipment requriement....)
Click to expand...

For a standard to have merit it must be measurable AND enforcable. In this case the measure is dependent upon a magnetic compass which is subject to myriad inaccuracies and certainly not STANDARDIZED from plane to plane. So in reality compliance only gives the appearance of following a standard and isn't enforcable anyway as they will not know which method the pilot is flying (at least until they have certifieably accurate and up-to-date wind info). In truth, ATC monitors the "big picture" in real time and makes adjustments as required whether you fly HDG or TRK.

If airplane X has a compass error of 10 deg left, and airplane Y has a compass error of 10 deg right and ATC gives them each the same HDG instruction what standard is being executed?

Here are the compass calibration requirements from FAR 23

FAR 23.1327

Magnetic direction indicator.

(a) Except as provided in paragraph (b) of this section--

(1) Each magnetic direction indicator must be installed so that its accuracy is not excessively affected by the airplane's vibration or magnetic fields; and

(2) The compensated installation may not have a deviation, in level flight, greater than ten degrees on any heading.

(b) A magnetic nonstabilized direction indicator may deviate more than ten degrees due to the operation of electrically powered systems such as electrically heated windshields if either a magnetic stabilized direction indicator, which does not have a deviation in level flight greater than ten degrees on any heading, or a gyroscopic direction indicator, is installed. Deviations of a magnetic nonstabilized direction indicator of more than 10 degrees must be placarded in accordance with Sec. 23.1547(e).


Even the FAA allows for 10 degress of error and even more if it is placarded. How many pilots update their compass calibration card annually? How many even look at it and compensate while flying an ATC HDG?

More often than not TRK is well within this 10 degrees of HDG unless you are in a hellacious xwind.
 
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tkatc said:
Nicely done. I couldn't agree more.

Let me play Devil's advocate though...how would the controller issue you a track? Fly North? Fly east? Fly direct some obscure waypoint that would take you precious seconds to find and enter?

I haven't even thought about flying a track so I may be green here, but it MUST be harder than flying a heading.
Click to expand...


A good controller in the situation you mention would give the following clearance. "RV999 fly heading 280 proceed direct MAVIN when able." He is giving you the initial direction and allowing you time to find the fix and set up your nav system.

George
 
dedgemon said:
Why would they CARE what your heading is? They don't, they care about your track. The heading thing is now just a historical relic. :D
Click to expand...


They care because not every aircraft has track. Every aircraft has heading. When they give you a heading it may be for several different reasons. They may want you going to a fix but they might also have traffic to your left so start you out going 10 right of the fix. If you assigned a heading and fly a track and a loss of separation occurs you will get a flight violation. Heading is heading and track is track. They are two very different things.

George
 
sailvi767 said:
A good controller in the situation you mention would give the following clearance. "RV999 fly heading 280 proceed direct MAVIN when able." He is giving you the initial direction and allowing you time to find the fix and set up your nav system.

George
Click to expand...

In your example, the controller is issuing a clearance DIRECT to a point, which is what he wants. Wind be damned he knows you are equipped to go direct to that point. But until you have that equipment dialed in for MAVIN, a GOOD controller derived that 280 HEADING based upon the direction he wants you to fly while compensating for winds.

Flying a HEADING is simpler, quicker and more efficient as you have proved in your example. Further, if the controller is not worried about you drifting for a few miles, he might omit an initial heading because he is not trying to miss other traffic or airspace. Please don't think if you don't hear a heading issued with a DIRECT to clearance that you are dealing with a substandard controller.
 
A quick check of Part 43 appendix D reveals no requirement to re-calibrate the mag compass.

How many of you guys with EFIS systems are checking your compass calibration when you update software versions? Don't think it can be messed up? Wrong. How about when you add an ADS-B receiver or new radio?
 
tkatc said:
Flying a HEADING is simpler, quicker and more efficient as you have proved in your example.
Click to expand...

tkatc - I think this is dependent upon how the pilot sets up his/her GPS. Even most handhelds have options to display TRK info on the screen. Flying to a track isn't any differnt than to a heading from a procedure point of view. Just turn in the desired direciton, watch track change and stop turning when approaching the new track.

EFIS systems with integrated mapping is even easier as you can adjust the track to the intended destination visually - particularly helpful in the "cleared direct to" scenario discussed.
 
Ironflight said:
Because the controller has the big picture about the traffic he (or she) is handling, and you don't. Standards exist to STANDARDIZE - they use heading for everyone (as mentioned above by actual Air traffic Controllers), and they don't have to figure out who is flying what (heading or track). If you're IFR, then play by the same rules as everyone else. The rules might seem silly, but at least they put us all on the same page.

(And yes, I'd support a change to the standards if they wanted to make everyone fly "Tracks" instead of "Headings". It would make sense. it would also mean that every airplane in the system was required to have on board track guidance - yet another equipment requriement....)
Click to expand...

Okay,
you can standardize my heading command, but not my speed (drift rate), or my instrument errors.

We're arguing over something that isn't terribly accurate here.

I wasn't suggesting that we change anything. I think the whole argument is a bit pedantic really.

The heavy iron drivers can now spend all afternoon arguing about it. :D
 
This is no different than the argument whether you should fly to Indicated or Ground speed when ATC asks you to maintain a certain speed. You have to assume these requests are geared to the lowest common denominator... All aircraft have magnetic heading indication, and all aircraft have indicated airspeed. Everything else is a bell and whistle on top of that.

If you have the capability of dialing an autopilot to the GPS track, certainly it's not that difficult to dial it to the magnetic heading instead? For that matter, would it be all that difficult to use your GPS as the reference to fly a magnetic heading? Your GPS surely knows the magnetic variation wherever you are and could tell you what the magnetic heading is...
 
I find that I will do what the controller asks of me. "turn to a heading of 360" I turn so my heading is 360. If they say, "clear direct 10 mile final contact tower." I fly the track required to go straight to 10 mile final. Pretty simple, do what they ask.
 
Kobwo said:
I find that I will do what the controller asks of me. "turn to a heading of 360" I turn so my heading is 360. If they say, "clear direct 10 mile final contact tower." I fly the track required to go straight to 10 mile final. Pretty simple, do what they ask.
Click to expand...

AMEN!!!!!!
 
tkatc said:
I haven't even thought about flying a track so I may be green here, but it MUST be harder than flying a heading.
Click to expand...
No, it's actually very easy.
dedgemon said:
We're arguing over something that isn't terribly accurate here.
Click to expand...
I think that's what Ken K. has been trying to say.
dedgemon said:
I think the whole argument is a bit pedantic really.
Click to expand...
Pedantic! I had to look that up. Isn't using words like that a violation of the posting rules?:D
 
I just have to throw...

some more gasoline on this fire :D

-- FAASafety.gov --------------------------------------------------------

Your Aircraft Systems May be Vulnerable
Notice Number: NOTC4031

!!! CAUTION !!!
Magnetic disturbances or magnetic flux fields propagated by underground/buried or surface objects made of steel can cause significant directional heading errors in slaved compass system(s) indications . . .Many low-wing airplanes, including some regional airliners, as well as helicopters, are susceptible to magnetic disturbances caused by buried- and surface-objects containing or made of steel Directional heading errors have contributed to loss of separation between aircraft during initial departure and subsequently caused the issuance of pilot deviations Such errors have been documented to be up to 40 degrees Errors in heading may be indicated on one or both installed slaved directional indicators (HSI, EHSI, PND, etc.) which MAY or MAY NOT be detectable and alerted to the pilot by a comparator monitor, if installed Heading error indications vary in magnitude and may be observable in the same or different directions, depending upon flux field density
For more information and what to do click on the link below: https://www.faasafety.gov/files/notices/2012/Aug/CAUTION_TLP_031612_Rev10.pdf
Note: If this email ended up in your Junk or SPAM folder, please add our Domain name to your Safe Sender List (@FAASafety.gov), and not [email protected] or [email protected].
 
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