Visibility Range

[Darrol Larrok 1140797]

What's funny is that (in retrospect), there doesn't seem to be an actual problem to resolve here, just issues of principle.

[Salvatore Barcia 1055319]

Posted in ZMA's forum. Seems like an issue that is still going on today. Most of the time people forget to reset their range when signing on the network. I use to do it all the time.

[Adam Lagoda 827397]

Hello,

 

I have a question - on the topic, I guess.

 

There are two types of range on client ([Mod - Happy Thoughts]ume EuroScope as it's the most popular one) - scope range and audio range. The first one is regulated by range we have set in client while connecting. The other one is - from what I've learnt from Miguel, VATEUD8 - fixed, depending on station set. Example - CTR - 400nm. Is that correct?

 

On the other hand, the "visual" range might be otherwise regulated using vis command. Both in terms of center point, and range (using subset of vis1..vis4 - if properly set, it nearly doubles the range from your setting). How does that affect radio range? Is that vis-independant, or not? How the vis1..vis4 sets affect the radio range, if any?

 

I need all the information you can provide, as two stations which should be independent and not interfering, are interfering.

 

Thanks in advance,

 

Adam

ACCPL3, Operations Officer

[Neil Farrington]

There are two types of range on client ([Mod - Happy Thoughts]ume EuroScope as it's the most popular one) - scope range and audio range. The first one is regulated by range we have set in client while connecting. The other one is - from what I've learnt from Miguel, VATEUD8 - fixed, depending on station set. Example - CTR - 400nm. Is that correct?

 

On the other hand, the "visual" range might be otherwise regulated using vis command. Both in terms of center point, and range (using subset of vis1..vis4 - if properly set, it nearly doubles the range from your setting). How does that affect radio range? Is that vis-independant, or not? How the vis1..vis4 sets affect the radio range, if any?

Hi Adam - your wording is a little confusing, but I essentially understand what you're asking. Skip to the bottom for a brief summary, as I've made things even more complicated.

 

In Euroscope (and any other controller client), the range that you set in the connect dialog is a set radius, for example 400nm. The range set on that slider is generally referred to as the vis(ibility) range, and is directly related to the visibility point that is set. The visibility range is the radius extending outwards from the visibility point.

 

Primarily, this means that the controller sees live, active traffic that is within 400nm (using our ongoing example) of that visibility point. That is what you've referred to as the scope range.

 

The audio range is directly related to the scope range, and is also regulated by the visibility range set in a client. If I set a vis range of 20nm, aircraft 100nm away won't be able to join my voice frequency. However, if I set a vis range of 100nm, they will be able to, and at that point, I will show up in their ATC list on their pilot client.

 

What I can also do is set another vis point/vis centre. If I'm controlling in the UK, and set a vis point in the US, those controllers with overlapping ranges in the US will see me in their controller list, and pilots will be able to join my frequency, even though I'm still controlling in the UK, and my primary is still in the UK.

 

Summary:

So, in answer to your question, vis1-vis4 directly affect the radio/audio range, and increasing/decreasing the range will have an effect on how far out aircraft can contact you. This may also be further affected by the range of the pilot client, however I cannot say for sure, and is irrelevant here anyway.

 

In the case of overlapping frequencies where pilots are connecting to the wrong frequency because they are identical, the controllers need to reduce their vis range, and unset any additional vis centres/vis points.

If it is a common occurrence when the two positions online, VATSIM procedure may need to be for one of those frequencies to be changed.

If it is an uncommon occurence, and happens only when a specific person is online, it is likely they have a specific setup that is affecting it, such as a higher vis range/additional vis point.

 

It simply depends on the distance between the positions, and the type of positions, as to whether any further action needs to be taken.

[Adam Lagoda 827397]

Thanks Neil for your answer, and sorry if my English is out of standards - I've been using this mostly with european teams, and - as you probably know - European English is nowhere near English English standards

 

So, there are no separate ranges for scope and radio? If so, that's confusing. In Poland, there's a station at Modlin (TWR), using the very same frequency as Bremen CTR. As Modlin is more or less 300nm from the pl-de border, one would [Mod - Happy Thoughts]ume they will be completely independent. But what we learned from those few times Modlin was manned and Bremen online - they're not. I was thinking it's some misconfiguration problem rather, than anything else. However, how could two stations affect each other with such a large separation? Hmmm. No idea now. TWR would be easily idetified as source if range was too large. And I can hardly think of CTR working with range 250nm beyond own borders.

 

Anyone else eager to comment? Any help is appreciated to understand and solve the problem.

 

Thanks,

Adam

[Neil Farrington]

Thanks Neil for your answer, and sorry if my English is out of standards - I've been using this mostly with european teams, and - as you probably know - European English is nowhere near English English standards

 

So, there are no separate ranges for scope and radio? If so, that's confusing. In Poland, there's a station at Modlin (TWR), using the very same frequency as Bremen (the B part). As Modlin is more or less 300nm from the pl-de border, one would [Mod - Happy Thoughts]ume they will be completely independent. But what we learned from those few times Modlin was manned and Bremen online - they're not. I was thinking it's some misconfiguration problem rather, than anything else. However, how could two stations affect each other with such a large separation? Hmmm. No idea now. TWR would be easily idetified as source if range was too large. And I can hardly think of CTR working with range 250nm beyond own borders.

Not at all, your English is perfect, it's just not the easiest of topics to explain.

 

No, there are no separate ranges for scope and radio - they're both related to the set visibility range on the client.

 

As Bremen Radar is a CTR position, they can often have a high vis range of 300nm+, and of course, some controllers also overextend. The distance between Bremen and Modlin is 400nm-450nm, so really, all it would take is a 400nm vis range for the positions to overlap, on top of any additional range added by the pilot client.

 

The next time it happens, you could do a little investigating:

For the purposes of obtaining the required information, you will need to use VRC (for the additional information it shows). In the controller list, find Bremen and Modlin, and check their vis ranges as shown by VRC. Then right-click in each, and select 'Show Location' - this will show where their primary vis point is set, and their vis range. This will allow you to visualise the overlap, and see how close they are.

 

At the end of the day, the overlap itself won't be the issue - aircraft near to Modlin and further east will only pick up Modlin, and aircraft nearer Bremen and further west will only pick up Bremen. The problem area will be directly in between, where the pilot client is between the vis points and picks up both stations.

 

Generally, it's unusual for this to happen, as most countries ensure that centre positions have different frequencies to local positions due to overlap, but because VATSIM works a little differently to real world, we do get this overlap sometimes.

[Ross Carlson]

Unless things have changed since I last looked at the server code, there are separate range values in play for radio versus radar. The visibility range that the user sets in the client affects only radar range. It determines the radius within which the server will send you target position data. So, it determines which blips you see on the scope.

 

Your radio range determines which pilots (and other controllers) see you on their controller lists. Radio range is independent of visibility (radar) range and the visibility range setting has no effect on radio range. Radio range is determined by the server based on the facility type you sign in with and it is a fixed value. I can't remember the exact numbers, but it's something like 5 for GND, 25 for TWR, 100 for APP, 400 for CTR, etc. (Again, those are just guesses to illustrate how it works ... they are not necessarily the real numbers.)

 

It's important to note that radio range for controllers is fixed (as described above) but it is dynamic for pilots, since a pilot's radio range is a function of altitude. The server determines whether or not a pilot should see a controller in his controller list by determining the pilot's radio range (using altitude) and checking if that range overlaps with the controller's range. So a pilot on the ground 450 NM from a CTR controller may not see that controller, but that same pilot at 35,000 feet (still 450 NM from that controller) will see that controller, because at that altitude, the pilot's radio range is much larger, and will thus overlap with the controller's 400 NM range. (On a side note, this calculation uses the pilot's altitude MSL, not AGL, so a pilot on the ground at Denver has a much longer radio range than a pilot on the ground at Boston. )

 

To confuse things a bit, while the visibility range has no effect on radio range, the visibility points do have an effect. When making the above determination as to whether or not a pilot should be able to see a controller in his controller list, the server does the overlapping range check once for each of the controller's visibility points. (Same for checking if controllers can see each other.)

 

Summary: Visibility range affects only target visibility and is set by the controller. Radio range is not affected by visibility range and is a fixed value for controllers, and a dynamic value calculated by the server for pilots, based on altitude. Visibility points apply to both.

 

Again, this may have changed since I last looked at the server code, which was a few years ago.

[Neil Farrington]

...

I've done a fair amount of late night controlling in the past, and given that I am the only position online, I often get pilots from airports a number of miles away calling me up, and very occasionally, a new pilot who ends up keying up on frequency and continuously transmitting. While I try and help them fix whatever problems they're having, I tend to reduce my vis range away from the aerodrome they're at, so that they drop of my frequency, and I don't get a 4AM earache.

Given that they do drop off my frequency after the vis range updates, this is my basis for audio being connected to the visibility range, rather than the station type.

 

The server using altitude to determine a pilot's vis range in terms of controllers in range is news to me, though - I would have [Mod - Happy Thoughts]umed this would be the same as what is set by the pilot client.

 

Edit: Although, that said, I often have multiple vis points set myself, so I may be struggling to remember whether it's lowering my vis range or removing the additional vis point that does cause them to drop off.

[Miguel Frias]

It will most certainly be removing a vis point.

 

In LPPC for instance we have a special "X" waypoint that was calculated as the mean point, the center point of the FIR. However, by as low as about 20nm, We need an extra visibility point to get the farthest northeastern traffic to see us as a controller (radio range). While my range is 600nm, they cannot tune into my frequency. When I create a second point, it extends the radio range to the intersection of both circles, hence allowing for the pilots to tune in. If I remove that second visibility point, they'll drop off from frequency, sure thing.

[Mike Evans]

Ross is correct, your Visibility range as set in the Controller client has no bearing on radio range..

[Adam Lagoda 827397]

Ross, Mike, Migues,

 

Thanks for confirmation. Is that also centered around visibilty points? Hopefully, this is the solution then - to properly use vis1..vis4.

 

Thanks again.

Adam

[Ross Carlson]

Thanks for confirmation. Is that also centered around visibilty points? Hopefully, this is the solution then - to properly use vis1..vis4.

 

Yes, both your visibility range (radar range) and your radio range are centered on your vis points.

[George Papafilis]

When those questions arise, I always point at this thread also:

 

http://forums.vatsim.net/viewtopic.php?f=7&t=56924

[Adam Lagoda 827397]

It will most certainly be removing a vis point.

 

Miguel, your guess was right

Yesterday I managed to run some checks. On standard, both stations do not interfere (with quite a margin, I moved my vis2 from Mofdlin to Poznan, by nearly 200nm with no effect). However, if station Bremen A serves as B as well (to provide ATC on all areas of ATC zone which is more-or-less rectangular with width twice as big as height), it's quite usual for them to set up another visibility point over eastern Germany, and that's most likely causing the problems.

We'll work together with German ATCs to see whether it can be solved by small steps.

 

Thanks everyone for your help, the knowledge here (and on thread pointed out by George, thanks mate) is invaluable. Appreciate your help, really.

 

Have a nice day all of you.

 

Adam

[Roland Collins 800023]

It is worth mentioning that if you temporarily change your vis point it affects your visibility; which means to some aircraft and controllers you seem to have suddenly logged off.

 

In VRC if you change your view by RMB dragging or by using “.centre” is does NOT affect your vis point and how others see you. If needed you can set up another vis point, of course.

 

Roland Collins

[Bradley Grafelman]

In VRC if you change your view by RMB dragging or by using “.centre” is does NOT affect your vis point and how others see you.

... unless, of course, you forget to set a fixed vis point after you open VRC since, for whatever reason, visibility points are not saved in session profiles.

[Roland Collins 800023]

The default vis point is usually defined in the sector file; well at least it is in all sector files I've worked on and defining one is certainly best practise.

 

Roland Collins

[Bradley Grafelman]

The default vis point is usually defined in the sector file; well at least it is in all sector files I've worked on and defining one is certainly best practise.

Er... best practice? Even though there could be hundreds of positions in a given sector (from DEL on up) and one vis point to rule them all?

 

At any rate, there is no default vis point in the sector file - only a default center point (which is ignored once you save your own session profile). Without doing a ".vis" after opening VRC, you have a floating vis point that follows the center of your scope.

[Mike Evans]

The default vis point is usually defined in the sector file; well at least it is in all sector files I've worked on and defining one is certainly best practise.

 

That point is an arbitrary point to define the "center" of the sector.. I know ASRC never used it to set a vis point, I'm fairly certain VRC doesn't either..

[Ross Carlson]

The default vis point is usually defined in the sector file; well at least it is in all sector files I've worked on and defining one is certainly best practise.

 

That point is an arbitrary point to define the "center" of the sector.. I know ASRC never used it to set a vis point, I'm fairly certain VRC doesn't either..

 

It doesn't ... though it does set your scope center point to that point when you first load a new sector file, and your center point is your visibility point until you set one with a dot command.

[Oliver Gruetzmann]

However, if station Bremen A serves as B as well (to provide ATC on all areas of ATC zone which is more-or-less rectangular with width twice as big as height), it's quite usual for them to set up another visibility point over eastern Germany, and that's most likely causing the problems.

Usually this shouldn't happen. We do have the combined EDWW_CTR for that purpose.

 

What Station does 123.925 interfere with (just interested)?

[Meinolf Hoehler]

EDWW_A_CTR, if the frequencies haven't changed since i did your neighbor PADH

Edit: In Poland its Modlin TWR, stated somwhere in the looong posts above

[Adam Lagoda 827397]

Usually this shouldn't happen. We do have the combined EDWW_CTR for that purpose.

 

I know it shouldn't. I also know it does (last Warsaw Overload an example).

 

I also did some tests with both E and W, and it takes a lot of movement to the east (or to the west from Poland) to interfere. That's why I opted for leaving things as they are, and asked my fellow controllers to check once we have that sort of interference again, to see if it's a problem of setting vis1..4 to the East.

 

Adam

[Oliver Gruetzmann]

We should have sorted it out on our side. No need to move the vis point to cover the whole FIR.

[Jon Story 1357003]

I wonder if there's a combination of technical and education solutions that could be used here?

 

Rather than strictly enforcing the range, which could raise objections in some circomestances, eg when supervising a student (I'm not a controller, so these specifics are a little beyond me)... why not lightly enforce it.

 

By which I mean: automatically set the "correct" range when connecting, and then allow it to be specifically over-ridden by the user. Currently it appears we're just asking the user what range they would like and then accepting that, but this solution would allow the correct range to be applied by default to the vast majority of users. For the few who do need to change the range for some reason, that option will still be available to them: for the rest, it will automatically be set and they're unlikely to ever change it deliberately.