Heading/Course difference

[michal 44]

 

 

In selective HDG mode, does the FMGC use the wind triangle to try to match HDG and TRAK?

No.

[Dave Morgan 68]

Hi.

 

A strange question....what is the difference between course and heading?
 

 

In a nutshell, course is the direction your plane is moving and heading is the direction in which the nose is pointing.

 

...

 

Your track is just the (imaginary) line the plane is following - it doesn't even have to be straight.

 

As so many others have already told you, you need to learn some fundamental stuff. The way you are going about things is a bit like trying to understand calculus before you can do simple sums. If you keep asking about the complex stuff, some of the basics will come along with the answers but people will probably misunderstand you as you don't have the knowledge to describe what you want to know.

 

Regards,

D

[AF330 0]

I disagree, the AP/FD has to compute 'first guess' wind correction angle and for this it needs some basic trigonometry. Plus there is a ton of great-circle formulas that FMC must know how to compute so it is in fact quite loaded with all kinds of formulas.

Yes of course! I am going to get a book explaining basics of flight for christmas!!

 

But when does the plane use tge wind triangle? In managed mode, it already uses TRK so no need to use the wind triangle. In selective mode, it uses HDG only...

 

So CRS is basically more "important" and should be respected. That's why, ILS has got a CRS and not a HDG because the plane should remain in the correct direction....Right?

Well, ATC will include wind factor while giving a HDG....

 

Thanks

[RickB1293 9]

Try this analogy. You're in a boat and want to cross a mile wide river to reach the marina. The river has a current of 5 knots, the cross wind. Take a compass reading from your beginning point toward the marina, this is your True Course.

 

Now begin your trip to the marina. If you follow the compass heading you initially took and the boat is moving at 5 knots on the speedometer you are making 5 knots ground speed. At the same time the river current is pushing you down stream also at 5 kts. The point you will reach while maintaining the initial heading will be one mile down stream of the marina, because you are going 5 kts down stream and 5 kts along your compass heading. Trigonometry will tell you how far you actually travel thanks to good old Pythagorus (sp?).

 

The path the boat actually makes to reach the down stream point is your track, also called course over ground or COG. If you want to go directly to the marina, you'll have to add a correction factor to your magnetic heading to compensate for the current. The correction factor can be found by doing the math, using a computer (paper or electronic) or letting the autopilot do it for you. In this simplification you would take compass reading of a point one mile upstream. The initial heading to your destination plus the correction factor for the drift. This will result in COG=Initial Heading=True Course.

 

Of course actual aeronautical navigation is more complex because of the greater distances travelled and the fact that the world is round, but the theory is the same. All of this is better explained in any book on navigation or even Wiki it's called vector arithmetic.

[AF330 0]

Thanks a lot!  :wink:

 

But when does the A/P use it? When we our in NAV, the plane uses tracks, so no calculation to do. It knows which CRS to go. In selective mode, the plane doesn't use the triangle...we enter a HDG, it points the plane to that HDG. So when does A/P calculate how to equal HDG and TRACK (or COG)? In which situation?

 

In manage mode, when we enter an airway, it knows the track to keep. So it doesn't use HDG. So no need to calculate the triangle. In selective mode, it only uses HDG...

 

So it gives:

 

Managed mode: Tracks only - to follow the right CRS.

Selective mode: HDG only.

 

Hope you understand my question,

 

Thanks a lot,

A.Roy

[pschlute 37]

So when does A/P calculate how to equal HDG and TRACK

 

HDG is HDG

 

TRK is TRK

 

TRK and HDG will only be the same in a zero crosswind situation. The AP cannot make them equal each other if there is crosswind. The AP is either flying a HDG or it is flying a TRK.

 

I am afraid your question makes no sense.

[Dave Morgan 68]

Hi.

 

So CRS is basically more "important" and should be respected. That's why, ILS has got a CRS and not a HDG because the plane should remain in the correct direction....Right?
 

 

Your question about ILS illustrates what I posted earlier but if you are referring to ILS approaches rather than the hardware, then the answer is yes. If you set a heading rather than flying the course you'd be doing the same as the plane on the right in this animation:

 

http://www.physicsclassroom.com/mmedia/vectors/plane.cfm

 

 

Here's one from the real world. Watch the crosswind landings in this clip. You can see the planes travelling parallel with the runway (course) but pointing well off to one side (heading), just like swimming across a river. If they were using an ILS localiser, it would be pointing out from the end of the runway in the direction they'd just come from.

 

https://www.youtube.com/watch?v=la-hSjKP2TU

 

Cheers,

Dave

[AF330 0]

Thanks a lot....

Hmmm.... Let me ask my question this way:

 

We we enter an airway in the MCDU, what does the FMGC know? It's track, isn't it?

[pschlute 37]

Thanks a lot....

Hmmm.... Let me ask my question this way:

 

We we enter an airway in the MCDU, what does the FMGC know? It's track, isn't it?

Yes

[AF330 0]

Great....

 

So what else does the plane know?

Does the plame know our current track? Our current HDG? How? With IRS qnd GPS isn't it?

 

Thanks

[michal 44]

 

 

With IRS qnd GPS isn't it?

Instead of asking endless nonsensical questions ask yourself this - how come an airplane could keep heading before someone invented IRS or GPS?

And how come an airplane could maintain a course before invention of IRS or GPS or MCDU or FMGC,...  

I suggest you learn about aviation how it was in 1920, 1940, 1960, ... maybe this way you can comprehend some of the fundamentals of aviation.

And stop throwing around all these acronyms like MCDU, IRS, FMGC, I am sorry but the more you use them the dumber you sound.

 

By the way, how old are you, perhaps this could shed some light on the situation?

[Dave Morgan 68]

AF330 -

 

If you want useful and understandable answers out of us then do us a favour and let us know some background so we can give replies that meet your needs:

 

Answer the following questions, and do it honestly.

 

Is your interest more in operating a FMC or in flying a plane?

Have you got a flight sim, and which one?

Are you interested in navigation generally (orienteering, sailing, map-reading et c.)?

Can you sit and read text-books for more than a few minutes before your attention wanders?

What sort of grade have you reached in maths?

Where are you getting your information from (I see lots of jargon - LNAV, FCU, HDG, IRS - but not much fundamental understanding)?

 

Cheers,

Dave

[AF330 0]

Hi

 

Just read your answers, have just come from school....will answer in detail this evening!

[AF330 0]

AF330 -

 

If you want useful and understandable answers out of us then do us a favour and let us know some background so we can give replies that meet your needs:

 

Answer the following questions, and do it honestly.

 

Is your interest more in operating a FMC or in flying a plane?

Have you got a flight sim, and which one?

Are you interested in navigation generally (orienteering, sailing, map-reading et c.)?

Can you sit and read text-books for more than a few minutes before your attention wanders?

What sort of grade have you reached in maths?

Where are you getting your information from (I see lots of jargon - LNAV, FCU, HDG, IRS - but not much fundamental understanding)?

 

Cheers,

Dave

 

Good evening,

 

I understand that you require more information about me....you still want to know why I am asking all these questions at my age... :huh:

 

Ok, here it goes:

 

I) AF330?

 

My name is A.Roy and I am 14 years old. I live in Paris, France. I am sure that you have noticed that I don't have a very good english! I have always been to french classes...but I have gone to the British Council, and have passed their bilingual test! (I had been for 1 and a half year in Dubai in an english school!). It helped me a lot!

 

I have always liked planes (I was 3 years old!). I have always flown Air France and It has always been my favourite airline! Today, when I know that I will fly AF, I am always very excited before the trip...

 

II) Answer to Dave Morgan:

 

1) Is your interest more in operating a FMC or in flying a plane?

 

Very nice question... 

Well, I love Airbus, so I also wanted to learn how to operate the FMGS - MCDU...

But, any day, I prefer to fly a plane! If you propose me to fly a real plane (C172...etc.) and enter data on the MCDU, without any hesitation, I would chose the first option....but in a sim, I would prefer to fly an Airbus as real as possible (FMGS, Check-lists....etc.) 

 

2) Have you got a flight sim, and which one?

 

I have got: Microsoft Flight simulator X PC DVD Games for Windows

This one: http://upload.wikimedia.org/wikipedia/en/f/fb/FSX_Cover.jpg

But I have got a MacBook so I have not even opened it....I should normally get X Plane for christmas but I am not sure to buy it because I tried to download the Xplane Demo and It was not able to display it...as It is a family Mac, it has got to many things in it (photos, videos....etc.)!  :rolleyes:

Will normally buy an Imac next year during summer holidays which will be more powerful.

So to make it short, no, I don't have any sim (well Infinite Flight on my Ipad!)...

 

3) Are you interested in navigation generally (orienteering, sailing, map-reading et c.)?

 

Oh yes! A lot, It is one of my biggest passion! I love reading maps, learning about countries, finding my way....etc. For christmas, I ordered this Atlas:

 

 

Hope I have answered your question...

 

4) Can you sit and read text-books for more than a few minutes before your attention wanders?

 

Yes! I love reading books....specially crime fictions: Agatha Christie, Sherlock Holmes...etc.

But It really depends of the book...If I don't get attracted by the story in the first pages, my attention can easily go away....

 

5) What sort of grade have you reached in maths?

 

In maths my average score on 20 this year is 17 and it was 18,5 - 19 last year.

But I am not very strong in biology and music.... :blush:

 

6) Where are you getting your information from (I see lots of jargon - LNAV, FCU, HDG, IRS - but not much fundamental understanding)?

 

I have always loved planes....I started watching these types of videos (in french, excuse me!):

http://www.youtube.com/watch?v=Ex_htH_wDWo

http://www.youtube.com/watch?v=-4AxBB5iVl0

http://www.youtube.com/watch?v=usbSYwm40Tc

http://www.youtube.com/watch?v=cZ-gqJRmHaM

 

And for this christmas, I have also ordered this book:

http://www.boutique.aero/article-35-le_guide_pratique_du_pilotage__zilio___15e_edition.aero

 

You can also find it in English:

http://www.boutique.aero/article-36-flying_practical_handbook__zilio.aero

 

Hope I have answered your questions! 

I will try to answer michal's questions...will just do some researches on it!  ^_^

 

Kind regards from Paris,

A.Roy

[mgh 89]

it also worth considering all the other posts AF330 has initiated before responding to him.