VIS Settings

[Dennis Whitley 952478]

Does anyone know why VRC alows 4 vis settings?

 

D

[Michael Hodge Jr 961044]

I would guess (and this is honestly a guess) for those areas that control very large sectors of airspace (i'm thinking oceanic stuff)

[Ross Carlson]

Very large, or strangely shaped sectors.

[Dennis Whitley 952478]

But wouldn't 600 "twice", rather than 4 times cover almost any FIR? And secondly, I thought Oceanic (to be realistic) would not use RADAR coverage.

 

D

[Alex Bailey 969331]

Miami Oceanic is mostly radar.

[Dennis Whitley 952478]

Doe's MIA need more than "1" 600 mile vis? And why would any controller, in the US, need "4" 600 mile vis ranges?

[Alex Bailey 969331]

No, Miami can get by with one vis range, but others may not be able to as Ross has alluded to.

[Jim Johnson 814050]

Doe's MIA need more than "1" 600 mile vis? And why would any controller, in the US, need "4" 600 mile vis ranges?

 

Not sure about 4, but I know that (at least) SLC and ANC need multiple vis centers to cover all areas that have radar coverage real world.

[Wade Williams 877539]

MSP is the only US Sector I know of that has to have two.

[Ross Carlson]

And why would any controller, in the US, need "4" 600 mile vis ranges?

 

VRC is used outside the US.

 

And realize that for an irregularly-shaped sector, several small vis ranges may cover the sector without a lot of overlap of adjacent sectors.

[Dennis Whitley 952478]

So some areas need additional vis to cover it all effectively rather than just 1 to cover it all?

Does two, three, or four vis settings consume more bandwidth than 1 vis setting?

[Keith Smith]

Why do you ask?

[Ross Carlson]

So some areas need additional vis to cover it all effectively rather than just 1 to cover it all?

 

Picture an L-shaped sector. 3 smaller vis areas would cover it with less overlap of adjacent sectors than one big vis area.

 

Does two, three, or four vis settings consume more bandwidth than 1 vis setting?

 

It depends ... using multiple *smaller* vis areas can be more bandwidth-efficient than using one large one. Essentially, the more area your vis areas cover, the more aircraft you will receive position reports for, thus the more bandwidth you will consume. Bandwidth consumption is directly proportional to the number of targets you see.

[Dennis Whitley 952478]

Interesting. SO, to be a bit more technical, does "tracking" an aircraft constitute more bandwidth usage? Verses a target that is not tracked? Our "Sandvine" (Bandwidth shaper) doesn't seem to show any difference.

 

However, we do block P to P traffic during certain peak periods, regardless of the bandwidth consumption. But, it appears that VRC only polls about 5 bytes during a 5 second interval.

[Ross Carlson]

Tracking an a/c doesn't change bandwidth consumption, no. There's just a couple packets exchanged at the point you initiate or drop track ... nothing ongoing during the track.

 

VRC does no peer-to-peer ... it only receives 5 second position updates.

[Keith Smith]

Ross, the G2G comms are p2p, no?

[Ross Carlson]

Ross, the G2G comms are p2p, no?

 

Yeah, but they're out-of-band ... direct UDP to the peer ... doesn't go through the server. (People often use p2p somewhat incorrectly when talking about position updates on VATSIM ... the high-frequency position updates that SB3 does are not true peer to peer ... they go through the server ... they're called p2p because they target a specific recipient, instead of being broadcast to all a/c within range.)

[Dennis Whitley 952478]

True. Not much data exchange at all. However, there are ISPs that address the traffic as PP. We look at it as any gaming software, or other applications such as Limewire etc. We "waveshape" in the evening peak to manage bandwidth. We don't block it, (most of the time), but it limits and delays proper useage.

 

Thus, some users may experience what they think is a VAT server issue, only to be that their ISP is playing tricks. This anomaly may exist between servers through IPS between server portals, thus appearing to be Sever outages.

[Ross Carlson]

Why is it cl[Mod - Happy Thoughts]ified as PP traffic by ISPs? Is it because it's not on a known port?

[Dennis Whitley 952478]

Yes, just as Limewire, other gaming software, etc that is "pinging" constantly. The Sandvine addresses it as a "broadcast" If it becomes an annoyance, "HOG". It may delay packet transfer indefinitely. Thus, rendering the application unuseable during peak traffic loading. Usually in the evenings between 5 an 11 P. Howevver, it will engage during Holidays, and rainy days. (People being home on unpredicted peaks) We also engage it at 3am for the benifit of commercial purchasers of bandwidth doing inventory etc.

 

ComCast for example is a big user of Sandvine. There are many other products that address packet spoofing etc at the tier-1 level that other ISPs use as well.

[Roland Collins 800023]

Does anyone know why VRC alows 4 vis settings?

Ross has mentioned very large or unusual shaped sectors and I’d like to expand on that.

 

The basic vis shape is circular; being centred on a point means you can't increase the range in one direction. If the range is increased it increases in radius and often extends into areas that were of no interest. This is inefficient and can result in poor use of bandwidth.

 

There are often situations where a controller has to look after aircraft that are transiting a vast area along a 'track'. This is not unique to oceanic; it happens with many large tracts of land, such as Russia and Africa etc. Medium size areas can be covered with an FSS range and certain overland FSS centres have been approved.

 

FSS on its own doesn't completely solve the problem. Using FSS meant that there had to be more FSS controllers to cover the 'track'; which was inefficient when considering the amount of traffic. Using FSS usually resulted in only a portion of the track being covered.

 

Having 4 vis point in line allows adequate single controller coverage along a track without extending vis range outside of the track. This method is consistent with the VATSIM desire to provide increase ATC presence and at the same time adequately cater for remote areas.

 

An increase in the basic vis range would have automatically given all controller clients extended omnidirectional capability however, multiple vis points provides flexibility for those who really need it and set it up.

 

Roland Collins

VP Regions

[Dennis Whitley 952478]

Agreed.

 

Some parts of the world "might" require more than 1 VIS for grographic consideration. However, as you mentioned, an FSS is operated differently. (Which gets 1500 Miles) and would probably have their hands full with "4" 1500 mile ranges set. If placed end to end, they would have 6000 miles laterally. Even a CTR position could have 2400 miles laterally.

 

I was however referring to the USA. With the exception of one or two areas, 1 VIS setting is sufficient. More times than I can count, I've seen LAX, NY, and ATL, and others have multiple CTR controllers on line with a 600 mile range. Especially during events where bandwidth might become an issue. Each overlapping by many miles. With exception of a few holes, the entire USA can be covered with 4 VIS settings of 600 miles. An OBS can do the same. They can set 4 VIS ranges with 600 miles, and watch the entire US Air System a a glance.

 

The key focus seems to be lack of controllers rather than increased VIS settings.

[David Spektor 948991]

I'm the training administrator in the Anchorage ARTCC. It takes at least three VIS points to cover the entire ARTCC if one is controlling center. The airspace is 1200nm by 1600nm. Even with 3, it's tricky to get every part of the airspace, so I always use 4.

[Keith Smith]

Dennis,

 

I'm a ZLA controller and I set up multiple vis centers so I can see handoffs from surrounding controllers who I otherwise have trouble seeing from time to time. Keep counting if you like, though.

[Dennis Whitley 952478]

Not counting anything! Just observing !

 

As several people have mentioned, "SOME" areas "MIGHT" justify 2, or "Possibly" more VIS Centers. However, 4 VIS centers, with 600 mile ranges, is "More" than sufficient for most areas. To be efficient, and realiistic, a vis center for CTR should be treated as a VIS center for TWR. The closer the CTR controllers are to each other, the less VIS required. Only cover the realistic area you need, not the entire panet!

 

"IF" there is a bandwidth problem, (which no one has really ever proven) then, better management of VIS centers would be instrumental in conservation of resources.

 

The newtwork, with some additional sophistication of resource management, "Could" be managed automatically. Meaning, A CTR controller's vis would change with number of controllers in the area. However, that would not be realistic either.

 

RADAR has physical limitations. RADAR is "Line of Sight" There are powerful RADAR sites that do see three to four hundres miles. HOWEVER...that is line of sight. Meaning, A RADRA center might see 300 NM, but as distance dimimsihes, the controller would only see aircraft at altitude, and at a proportional distance from the RADAER site. They would not be able to see an aircraft on the ground more than about 5 tp 10 miles. Depending on sitel elevation.

 

For the game to be realistic, CTR would not be able to see and taxi an sircraft that is located more than about 10 miles from the originating site (depending on terrian" Yes, there are remote RADAR sites, but that is another topic all together.

 

Basically, any ARTCC with multiple controllers (Possible Event), only needs enough VIS to cover their sector. Not 4 or 5 controllers in the same ARTCC, each using 600 miles vis.