Heading/Course difference

[michal 44]

Well, I love Airbus, so I also wanted to learn how to operat

You will NEVER understand Airbus unless you first understand other aircraft. No pilot begins his flying with an Airbus, they first fly something else, something a lot simpler.

I also suggest you find someone who speaks French and who can explain you most of this stuff. 

Also I urge you to make a trip to your closest local airport, find some private pilot willing to talk to you (in your native language of course) and perhaps draw/explain you some of this stuff. It may be a much better use of your time than sitting days behind the desk and trying to 'fly' Airbus.

[untoweechja 35]

 

 

You will NEVER understand Airbus unless you first understand other aircraft. No pilot begins his flying with an Airbus, they first fly something else, something a lot simpler.

 

I agree with Michael J. above:  Step out of an aircraft you manage and step into an aircraft you fly.  Find something small you like that has nothing more than the basics for navigation and do everything the old-fashioned way.  I think you'll be surprised how fast it all starts to make sense once you're doing the work yourself instead of letting a computer do it for you.

[AF330 0]

Yeah  :smile: ! I will try to do some C172 classes near CDG....

 

So, michal, I found that planes uses gyroscopes to find their HDG (INS calculates the position, the orientation and the velocity of the aircraft).

 

Unfortunately, didn't find anything about tracks...

 

 

We have to be at track X.

We know our position Y.

 

Does the plane know it's track AND his HDG?

Because If we know our position and our next position, we know where we are really going so we know our track.... :huh: Don't we?

 

Well I hope that the book I have bought will be able to help me....

 

EDIT: Can we say that velocity (speed with a movement) = track, where we are going at our speed.

And that orientation = heading, where the plane is pointing?

 

 

Thanks a lot,

AF330

[AF330 0]

If my EDIT is right, it would mean that plane knows it's track AND his heading....

[Dave Morgan 68]

Hi again.

 

We can certainly say that orientation is where the plane is pointing - it's a much better word than heading, but 'track' just means where the plane is flying.

 

Under correction, I think if you set a particular HDG the autopilot will keep the plane's nose pointed in that direction whereas if you specify a particular CRS then the autopilot will fly the course, usually something like a radial to or from a navigation beacon. I can't help with programming flight computers - I have much more fun flying by hand and making my own corrections for weather but the following picture may be helpful. Sadly I can't post it as I don't have permission. It shows dozens of tracks over London. You can see they don't really relate to course or heading.

 

http://www.duncanjauncey.com/blog/wp-content/uploads/2013/07/tracks_20130629_2.png

 

There's a very nice animated visualisation of tracks here ('UK 24' towards the bottom of the page).

 

http://www.nats.aero/

 

 

An autopilot's job is to make the plane's track the same as whatever you say it should be doing. If you tell it to fly a certain course it will just turn a bit more to the left when it feels like it's drifting too far to the right. What it 'feels' may come from INS gyros or from a satellite signal, or from a compass... It knows the plane's orientation but mostly just decides to go a bit more left (or right, or up or down).

 

There's a good glossary here which gives a clear distinction between course and track. It's interesting to see that 'heading' isn't defined:

 

http://www.faa.gov/air_traffic/publications/atpubs/pcg/

 

 

Some of us are inclined to take things too seriously. I don't think there's anything wrong with wanting to sim an A330 before hand-simming a C172. We all have different reasons for being so fond of what even Microsoft refer to as a game.

 

If your technical French is better than your technical English you might find some more help here:

 

http://forum.avsim.net/forum/270-forum-de-la-communauté-francophone-de-simulateur-de-vol/

 

Cheers,

D

[WarpD 824]

Ok... I see terms tossed about and definitions muddied up until things just don't make sense.

 

So... let's start with real basic definitions:

 

1 - Heading: a term that represents a direction taken by an aircraft without wind correction.

2 - Course: a term that represents a direction taken by an aircraft with wind correction.

3 - Track: a term that represents the resulting direction of motion with relation to the ground by an aircraft when flying a course or a heading.

 

At no point are any of the above terms interchangeable. They really just aren't. An autopilot is capable of following either a heading or a course. The result will always be a track.

[AF330 0]

Thanks for your replies!

 

So a simple INS gives heading and course indication to the aircraft.

 

1) The plane knows the course of the airway.

 

The plane knows it's course. It will go to the airway's course. So, we are in managed mode

 

2) We enter a HDG.

 

The plane knows it's HDG. It will go to the selected heading. So we are in selective mode.

 

I am not mixing HDG and CRS.

 

So when does the plane uses that triangle?

You use the triangle when your CRS is not equal to HDG and you want to match them.

 

In which situation does FMGC use that triangle? When it has to match CRS and HDG.....but it doesn't have to match HDG and CRS!!!

 

You say it: " At no point are any of the above terms interchangeable. They really just aren't. An autopilot is capable of following either a heading or a course"

 

Either.....

 

Thanks a lot...

 

I hope you got my question now!

[WarpD 824]

Oh, I understand your question completely... the problem is you keep mixing the terms.

 

When flying a heading, either manually or by automation... no correction is made for winds.

When flying a course, either manually or by automation... correction is made for winds.

 

It's just that simple. Always.

[AF330 0]

Ok....thanks a lot!

 

I had thought that a track is only for a course....excuse me!

 

Ok.....so in managed mode, the plane keeps calculating wind to keep the right track....

In HDG, it will just keep that heading....

 

1) Do you agree?

 

2) When we enter our airway, the plane knows it's Course. It doesn't pay attention to our HDG. But the triangle is used to calculate the angle between our heading and our course. But in our case, it doesn't even nead HDG. So does it remplace HDG by CRS of Airway?

 

Thanks

[WarpD 824]

Ok... the terms really don't care about 'managed mode'... that is an Airbus term that has nothing to do with how to fly an aircraft and understanding aviation terminology. I think you need to learn to separate what an Airbus term is from what an aviation term is. You're currently working really hard at making things far more complex than what they are.

 

As for your second item... you're mixing things up, yet again.

 

The 'airway', whatever that is... I don't know. Flight plans are defined by waypoints. Waypoints are flown based on great circle calculations. Beyond that... is a rather detailed and mathematically complex explanation as to how a flight guidance system calculates the necessary course between two waypoints and then adjusts both for course correction as well as wind correction. This value is what is used by the flight director to indicate what track the aircraft should be following.

[AF330 0]

Thanks a lot,

 

Hmmm....so in the FMGS, an airway is stored as a CRS I imagin and not as a HDG.

 

So can we say this:

 

In CRS mode, we don't use HDG. We just have to follow our airway's course. So in CRS "mode", does the FMGC change the air vector (true heading/ true airspeed) - yellow arrow to the course of our airway?

 

So yellow arrow = The course of our airway. Where we should be.

 

Green arrow = The track we are at with wind correction.

 

So the plane knows where we are and where we have to go. It doesn't use HDG in CRS mode only CRS. The track of an airway is a CRS and not a HDG.

 

Am I right?

 

Thanks

[WarpD 824]

No. Go back and read what I have posted.

[AF330 0]

Our posts are getting mixed! Wait....let me read your post.....we are writting at the same time!!

[AF330 0]

Ok....so let's leave managed mode....

 

I am not talking about airways but HOW to join an airway....

 

When Airbus/Boeing entered the airways in their FMGC, did they enter a course or a heading???

 

A course I imagine.....

 

The plane uses the wind triangle when it has to follow a track with a course....thanks to answer this question....

 

Kind regards,

A.Roy

[WarpD 824]

Why are you fixated on airways? Aircraft fly to waypoints. Even an airway is no more than a collection of waypoints predefined by a name. It's all about waypoints, waypoints... did I mention... waypoints?

 

Neither Airbus nor Boeing enter a course nor a heading.... because:

 

To navigate between waypoints requires using great circle navigation math. It's dynamic, not static. Great circle navigation defines a track that consists of a varying course value as the aircraft travels between the two waypoints.