Heading/Course difference

[Paul99 0]

I can only take so much of this.  Read this AF330, and don't forget when you get FSX  it will probably talk French to you so ALL of the above will be difficult to understand as the "technical" terms are different in French. Below is a little help from FSX in French. Oh, by the way, there is a French speaking forum here : http://forums1.avsim.net/forum/270-forum-de-la-communaut%C3%A9-francophone-de-simulateur-de-vol/%C2'>

 

Qu'est-ce qu'un cap ?
Direction vers laquelle un appareil se dirige, référencée par rapport au nord magnétique. Dans la mesure où le vent pousse l’avion en vol, le cap ne correspond pas nécessairement à la trajectoire de l’appareil au-dessus du sol. Par exemple, si vous voulez voler vers l’est par rapport au sol et que le vent vient du nord, il faut orienter l’avion légèrement dans le vent pour compenser la dérive.

cap magnétique
Direction dans laquelle un appareil est orienté. Elle est mesurée en fonction du nord magnétique. Le cap magnétique s’affiche sur le compas magnétique. Pour voler, un pilote détermine le cap magnétique en compensant la différence entre le nord géographique et le nord magnétique, puis il ajuste l’angle de route magnétique pour corriger les effets du vent. Si le vent souffle directement le long de la route prévue, le cap magnétique est égal à l’angle de route magnétique. Toutefois, si l’appareil est soumis à un vent de travers, le pilote doit tourner légèrement le nez de l’appareil dans le vent pour compenser. Dans ces conditions, la route au sol de l’appareil est légèrement différente de la direction dans laquelle il pointe son nez.


Imaginons que vous souhaitiez intercepter une orientation entrante de 270 degrés et que vous décidiez qu'une orientation relative de 45 degrés vous permettra de virer aisément quand vous parvenez au point d'interception. Quel cap devez-vous choisir ?

Une fois de plus, faisons appel à notre équation : orientation magnétique - orientation relative = cap magnétique. Autrement dit, 270 - 45 = 225. Le cap magnétique dont vous avez besoin est de 225 degrés. Vous suivrez ce cap aussi soigneusement que possible jusqu'à ce que vous atteigniez une orientation relative de 45 degrés et que vous commenciez votre virage à 270 degrés.

Dans une situation semblable, il peut être utile d'esquisser rapidement l'endroit où vous êtes et celui que vous souhaitez atteindre. Puis, sélectionnez une orientation relative.

Suivi d'une orientation

Vous pouvez même utiliser votre radiocompas automatique pour voler selon une trajectoire d'approche spécifique vers la station, aussi longtemps que vous n'oubliez pas la présence toujours possible d'un vent latéral. Vous devrez voler en crabe dans le vent comme vous le feriez si vous suiviez une ligne tracée sur votre carte pour une navigation à l'estime.

Par exemple, si vous suiviez l'orientation magnétique 330 degrés jusqu'à la station avec un vent de travers soufflant de la droite, l'aiguille se trouverait sur 330 degrés et vous pourriez l'imaginer comme représentant la ligne de route. Le nez de l'avion sur le devant du cadran se trouverait bien évidemment sur la droite, légèrement aux prises du vent latéral.

trajectoire
Chemin emprunté par un avion en vol.

trajectoire de vol
Chemin décrit à la surface du sol par un aéronef en vol.

 

Bonne chance,   

[pschlute 37]

 

 

You, the pilot... have exactly two.. only two and absolutely no more than two methods of commanding lateral control:

1 - Command/fly a heading to be followed, which will not use wind correction.
2 - Command/fly a course to be followed, which with either be a radial to/from a VOR or a great circle navigation calculated course between two waypoints. A GCN course uses both lateral deviation as well as wind correction and a VOR radial uses radio lateral deviation error correction.

That's it. You do NOT have any other options.

 

Not wishing to put a cat amongst the pigeons, but surely there is a third option.  Many autopilots have the ability for you to change the HDG selector to operate as HDG or TRK. If you select TRK and dial in 90 degrees, your aircraft will fly a 90 degree track. This is neither a VOR radial, nor is it a great circle route between two waypoints. It is simply a 90 degree track.

 

I am not a pilot, just a keen simmer.

[n4gix 4,947]

In simple language, here are explanations for the three basic modes:

 

AUTOPILOT MODES

 

HDG - Heading Mode The autopilot keeps the nose of the airplane pointed at the magnetic heading bug. If there is a crosswind, the aircraft's ground track will "drift" with the crosswind. For instance, if you wish to go to an airport that is 270 degrees from your location, but there is a wind from 180 degrees, you will end up north of your target because the crosswind pushed you north. This mode is generally only used when ATC tells you to fly a direction, since they assume you will use a compass and not a GPS to fly this vector.

 

TRK - Track Mode The autopilot uses GPS information to keep the ground track of the airplane on a straight line toward the heading bug. If there is a crosswind, the nose of the aircraft (heading) will not be pointed the same as the heading bug since the autopilot will adjust the heading to maintain a straight line over the ground. This is generally used any time the pilot wants to “hold” the direction of the aircraft without actually flying a specific GPS course or VOR radial. If the pilot hand flies the airplane off the track, the autopilot will correct back to the track, but this will not be the exact same line over the ground, since this is not a course line, but a ground track hold.

 

NAV - Navigation Mode The autopilot keeps the CDI needle that is displayed on the HSI centered. This CDI source may be a VOR, localizer, or GPS. Generally, this means the autopilot is flying you straight down a radial or direct to your GPS waypoint. This will fly you onto the GPS course or radial if you are off it when you engage the mode. If needed, the aircraft will maintain the correct heading to compensate for any crosswind. If you reach a GPS waypoint or change your desired radial, the autopilot will turn to intercept this new course.

 

[AF330 0]

Yeah...

 

Check this: http://www.efbdesktop.com/nav-autoflight/sys-13.2.10.html

 

What is this???????

 

So a teack is the path that you are flying. It's your route. The course is where you are really heading. The course is the heading of your track. So a CRS is where you have to go.

 

1) Do you agree?

 

2) What about the position of the aircraft in track mode? In HDG mode, the NOSE of the plane should POINT at the SELECTED heading.

So when you enter a track, the PLANE should follow that heading at a special angle? Because if we say that it has to folliw that track, it can follow it like in HDG mode....

 

Hope you understand my question!

 

@Paul: Merci de votre post, cela ne m'a pas vraiment aidé car les termes sont completements differents.... c'est plus orienté sur le cap magnétique et le cap....

 

As I am not sure you talk french (but Paul is a french name, isn't it?), here is it in english: Thanks for your post, but it didn't help me a lot because everything is different....it is not at all the same words!!! It talks more about magnetic heading and heading....

 

EDIT: Just read last post, what is HDG bug?

 

thanks

[michal 44]

  :ph34r:    B)  :excl:

 

We will be here a year from today listening to AF330's endless questions about course and heading.

AF330 - grow up, return to this forum in 2 years perhaps then you will understand. 

[AF330 0]

:ph34r: B) :excl:

 

We will be here a year from today listening to AF330's endless questions about course and heading.

AF330 - grow up, return to this forum in 2 years perhaps then you will understand.

Ha ha! Yes! But I just would like to understand this....because it's intresting and basics!

 

Thanks

Ok, ubderstood the heading bug!

 

Understood HDG and TRACK.

 

But want to confirm that course is where the plane is really going. So heading TCK = Course.

 

Thanks

[pschlute 37]

 

 

But want to confirm that course is where the plane is really going. So heading TCK = Course

 

For all intents and purposes  yes Course and Track are the same.  Heading is different.

 

Please , please, get yourself a sim and practice.

[michal 44]

 

 

But I just would like to understand this

 

You would like but you don't understand words spoken to you.

You twist everything which is given to you.

You need more than words, you need some audio-visual presentation.

I was telling you, you need to get out of your house, talk to pilots.

Aviation isn't done by sitting in your bedroom in front of your computer.

[mgh 89]

AF330's recent posts also make interesting(?) reading. They all show the same attitude.

 

EDIT: He seems to have put the same posts on FlightSim too.

Heading/Course difference 
Started by AF330, 09 Dec 2014 

Video Discussion: FMA A320 modes
Started by AF330, 26 Nov 2014 

FMA A320 modes 
Started by AF330, 22 Nov 2014 

ILS CAT III 3 Dual 
Started by AF330, 25 Nov 2014
 
A320 FCU Knobs
 Started by AF330, 20 Nov 2014 

Airbus FD and AP
Started by AF330, 11 Nov 2014 


Airbus FMGS/GPS-IRS/Radio
Started by AF330, 09 Nov 2014 


A320 Metric altitude PFD 
Started by AF330, 08 Nov 2014 

RMP/AMP Airbus 
Started by AF330, 02 Nov 2014
 
How do we calculate ft/nm?
Started by AF330, 31 Oct 2014 

Navigation Display VOR1 VOR2 Airbus
Started by AF330, 29 Oct 2014 

Airbus MMR and IRS connections 
Started by AF330, 09 Oct 2014 

A/THR and FD
Started by AF330, 09 Oct 2014 

A simple question on A/THR 
Started by AF330, 28 Sep 2014 

Trim Angle 
Started by AF330, 24 Sep 2014 

Fly-by-wire airbus
Started by AF330, 21 Sep 2014
 
Yaw turn coordination airbus 
Started by AF330, 23 Sep 2014 

Side-sticks airbus 
Started by AF330, 23 Sep 2014 

Rnav navigation 
Started by AF330, 17 Sep 2014

[AF330 0]

Yeah....exactly! Some on flight sim, pprune and some other french forums!

I take time to understand....I need to learn some things before understanding the answer!

 

So when we fly a course, we just don't just want to point the aircraft to that heading but we want to follow it. Am I right?

 

Thanks a lot!!!

[Bert Pieke 7,584]

Just to mix things up a little:

 

Entering a Course typically does not refer to the direction from your aircraft to the destination, but to the direction from your destination to your aircraft (or the reverse).  So, if you have a Navaid dialed in on the NAV radio, and you enter a Course, it refers to the radial to the Navaid that you want to follow.

 

So think of the Course as a line on the map that you would like to follow, whether you are currently on it, or not.

 

The autopilot may very well at first take you on an angle that intercepts the chosen Course direction.

[AF330 0]

Yeah, thanks a lot!

 

It' s a direction you would like to follow!

Do you agree with my previous post?

 

Thanks for your help!!!

[Bert Pieke 7,584]

Just remember that you may not be on the course at the moment you select it.. and have to get to it first, and then follow it.

 

It is a bit like saying that you would like to follow a major highway to Paris.

 

You select that highway.

 

If you are already on that highway, the autopilot will keep you on it.

 

If you are not, the autopilot will get you to that highway, and then follow it.

[AF330 0]

Great! It's a very good example!

 

So in HDG, we are on that highway. Our selected heading is 50°. We can go anywhere on that highway but we have to keep pointing at 50°. We can keep changing our track.

 

In course, we are on that same highway but we have to follow a special route. We can't do anything to follow 50°. We have a track that we have to respect even if there is wind. That track can be one of the highway's lanes.

 

Am I right?

 

PS: Lane is voie in french. Not sure of the word in english....

 

Thanks

[pschlute 37]

How many times do you need the difference explained to you ?