Radar Separation Minima
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Radar Separation Minima
Hello All,
I was just wondering if an Area controller somewhere out there could give me a quick pointer in the right direction.
Because I clearly don't have enough to do, I was looking for something in our Jeppy Text Manual the other day... (skip long and boring bit) ... so in other words, in the Horizontal Separation bit, I could see lots of stuff about longitudinal separation (based on time, DME, MNo etc.) but there were two bits I couldn't find.
1) Ignoring radar for a second, are there any lateral limits (i.e. could I be flying along an airway with someone 'on my wing' 20 miles away.
2) What are the minima for Radar control - how close can I be vectored to another aircraft.
Many thanks for any help,
NW3
I was just wondering if an Area controller somewhere out there could give me a quick pointer in the right direction.
Because I clearly don't have enough to do, I was looking for something in our Jeppy Text Manual the other day... (skip long and boring bit) ... so in other words, in the Horizontal Separation bit, I could see lots of stuff about longitudinal separation (based on time, DME, MNo etc.) but there were two bits I couldn't find.
1) Ignoring radar for a second, are there any lateral limits (i.e. could I be flying along an airway with someone 'on my wing' 20 miles away.
2) What are the minima for Radar control - how close can I be vectored to another aircraft.
Many thanks for any help,
NW3
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Have a look at this document for the UK:
http://www.caa.co.uk/application.asp...=detail&id=222
1) Yes there are.
2) Depends where you are. 5 Miles or 1000 ft is the usual
http://www.caa.co.uk/application.asp...=detail&id=222
1) Yes there are.
2) Depends where you are. 5 Miles or 1000 ft is the usual
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Carbide has pointed you at the UK controller's book of rules. When you read it - or even the bits that are of interest right now - for the first time it might not make much sense! Many bits of it are dependent on other bits to put in into context and this certainly applies to separations. You also need to know that, in the UK but also elsewhere, variations to the national rules can be permitted and are written into documents (MATS Part 2) that are not available on-line. This applies to area as welll as aerodrome ATC units. Some of the local variations that will affect pilots are published in the AIP but quite possibly not everything that that might interest the inquisitive.....or bored.....mind.
Your questions do not have generally applicable answers and sometimes will vary for reasons that are not immediately apparent. Just one example, although 5 miles horizontal separation is the norm, as you go further from a radar head the picture becomes less accurate and suddenly the 5 miles can become 8 miles just because you cross an imaginary line where the calculations of position accuracy exceed a particular value. In most cases there is more than one radar source available and the combined plot accuracy
is OK for normal ops but if one of those sources is out of service....
Hope this helps.
Your questions do not have generally applicable answers and sometimes will vary for reasons that are not immediately apparent. Just one example, although 5 miles horizontal separation is the norm, as you go further from a radar head the picture becomes less accurate and suddenly the 5 miles can become 8 miles just because you cross an imaginary line where the calculations of position accuracy exceed a particular value. In most cases there is more than one radar source available and the combined plot accuracy
is OK for normal ops but if one of those sources is out of service....
Hope this helps.
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Depends where you are. 5 Miles or 1000 ft is the usual
[SWITCH]DEVILS ADVOCATE MODE ON[/SWITCH] One has to ask why is it OK to reduce the separation... and if it is justifiable why eveyone doesn't use that as standard?
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So is it about fair to say that when flying around in the cruise, the horizontal separation (assuming no vertical separation) will be somewhere in the region of 5 - 10 nm (depending on a number of factors), with this decreasing to the normal separations on final that one would find on your bog standard glideslope?
Many thanks for the answers,
NW3
Many thanks for the answers,
NW3
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For convenience (one might argue), some airways are what is called 'deemed separated' which means that aircraft on them at the same level do not have to be on radar headings to prove separation. There are conditions associated with this, one of which is that if they are not on their own navigation exactly on the route they are supposed to be put on a radar heading. But it is inconsistent, for example:
UL602 and UY70 westbound across the North Sea in UK airspace are 12nm apart. Provided traffic at the same level and going in the same direction is following the route on its own navigation, it is deemed separated under radar monitoring. If both of them are, say 1 nm north of the route, they are no longer separated (though still 12nm laterally apart) and they must be on radar headings if at or passing through each other's level. They are also both under the control of the same controller. OK so far?
Now consider the area around LAM. Traffic from the East running into LAM is being controlled by one controller, who may well be using radar headings against his other traffic heading in the same direction. Another controller will be controlling traffic climbing out of the London area heading East which will, in some cases, pass 6 or so miles north of the westbound traffic passing through each other's level with no radar headings, coordination or other contact between the two controllers.
That's Ok too.
No inconsistency there, then!
WRT the original question, there must be some limit set for air routes to be separated without radar (and not the 60nm across the pond). What is it?
UL602 and UY70 westbound across the North Sea in UK airspace are 12nm apart. Provided traffic at the same level and going in the same direction is following the route on its own navigation, it is deemed separated under radar monitoring. If both of them are, say 1 nm north of the route, they are no longer separated (though still 12nm laterally apart) and they must be on radar headings if at or passing through each other's level. They are also both under the control of the same controller. OK so far?
Now consider the area around LAM. Traffic from the East running into LAM is being controlled by one controller, who may well be using radar headings against his other traffic heading in the same direction. Another controller will be controlling traffic climbing out of the London area heading East which will, in some cases, pass 6 or so miles north of the westbound traffic passing through each other's level with no radar headings, coordination or other contact between the two controllers.
That's Ok too.No inconsistency there, then!
WRT the original question, there must be some limit set for air routes to be separated without radar (and not the 60nm across the pond). What is it?
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there must be some limit set for air routes to be separated without radar
BTW UA34 tracks just parallel to the Dutch-London/Scottish UIR boundary. At one time UK radar coverage was minimal, so was this deemed separated from traffic operating to the east of the boundary? Always puzzled me and never got a satisfactory answer
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there must be some limit set for air routes to be separated without radar
Attachment A- Material relating to a method of establishing ATS routes defined by VOR
Attachment B- Method of establishing ATS routes for use by RNAV equipped aircraft
According to attachment B-minimum spacing between parallel tracks or between parallel RNAV route centre lines based on RNP type 5 (in non-radar environment) should be:
-16.5 NM in a unidirectional system
-18 NM in a bi-directional system
cheers
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OK so far most people agree the norm can vary from 3nm or 5nm or 1000'.
What about when A/C are on reciprocal tracks and information is received from radar that the A/c have passed, so a climb or descent can commence before the required 3nm separation is acheived
and before everyone says you're mixing and matching , I use Radar, but levels for inbound and outbound A/C are generally assigned on a procedural basis.
Discuss
What about when A/C are on reciprocal tracks and information is received from radar that the A/c have passed, so a climb or descent can commence before the required 3nm separation is acheived
and before everyone says you're mixing and matching , I use Radar, but levels for inbound and outbound A/C are generally assigned on a procedural basis. Discuss
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Spitoon, you're forgetting window pane separation (frequently used in the tower......not so much in a centre!) and of course frequency separation.
Eh? What do you mean they're not real ones??????
Eh? What do you mean they're not real ones??????
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Gonzo,
On a par with frequency separation is my old mil area radar trick: when separation gets a bit tight just drop the radar down a range scale. Hey presto! The blips suddenly get further apart
On a par with frequency separation is my old mil area radar trick: when separation gets a bit tight just drop the radar down a range scale. Hey presto! The blips suddenly get further apart
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Gonzo, I wasn't forgetting the one where I look out the window - I'm a TWR/APC man so it's daily business.......but you're right it's just one more separation that is available if the circumstances are right.
safety case asks what is the point of radar separation. Well, I'll treat this as a serious question but I'm conscious that I might be being suckered in here!
Each of the different separations has rules and conditions associated with it. Some separation standards are more efficient (i.e. you can put the aircraft closer together whist complying with the rules). As an illustration, and these are paraphrased and simplified, here are some examples.
With nothing but a stopwatch and radio two aircraft at the same level on the same route have to be 10 minutes apart - that's quite a long way if they're 737s. Have both the aircraft on tracks split by 30 degrees outbound from an NDB and they only need to be 4 minutes apart. It's all to do with how much confidence you have in the relative positions of the aircraft. With radar you can put two aircraft as little as 2.5 miles apart given the right radar equipment and circumstances (remember I said these were simplified examples) - because you know far more accurately where the aircraft are. Before I move on from radar though, one more point - don't be misled into thinking that what you might see on a radar is completely accurate, every radar picture suffers inaccuracies for a variety of reasons. Finally there's the window separation - or reduced separation in the vicinity of the aerodrome to give it its proper title. Here if the pilots or the controller can see what's going on and can make sure the two aircraft don't collide then they're separated. I believe this is the origin of the expression "a miss is as good as three miles".
Like I said before, the controller's job is to make sure that one of these separations exists between two IFR aircraft - which one the controller chooses is determined by the circumstances that pertain at the time. There endeth just about everything I know about the black art that pays my mortgage.
PS - safety case, please tell me you're not a controller!!!!
safety case asks what is the point of radar separation. Well, I'll treat this as a serious question but I'm conscious that I might be being suckered in here!
Each of the different separations has rules and conditions associated with it. Some separation standards are more efficient (i.e. you can put the aircraft closer together whist complying with the rules). As an illustration, and these are paraphrased and simplified, here are some examples.
With nothing but a stopwatch and radio two aircraft at the same level on the same route have to be 10 minutes apart - that's quite a long way if they're 737s. Have both the aircraft on tracks split by 30 degrees outbound from an NDB and they only need to be 4 minutes apart. It's all to do with how much confidence you have in the relative positions of the aircraft. With radar you can put two aircraft as little as 2.5 miles apart given the right radar equipment and circumstances (remember I said these were simplified examples) - because you know far more accurately where the aircraft are. Before I move on from radar though, one more point - don't be misled into thinking that what you might see on a radar is completely accurate, every radar picture suffers inaccuracies for a variety of reasons. Finally there's the window separation - or reduced separation in the vicinity of the aerodrome to give it its proper title. Here if the pilots or the controller can see what's going on and can make sure the two aircraft don't collide then they're separated. I believe this is the origin of the expression "a miss is as good as three miles".
Like I said before, the controller's job is to make sure that one of these separations exists between two IFR aircraft - which one the controller chooses is determined by the circumstances that pertain at the time. There endeth just about everything I know about the black art that pays my mortgage.
PS - safety case, please tell me you're not a controller!!!!
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Good point Lon, but, of course, NW3 is from London so I just went into UK mode (believe that and I've got a nice little runner you might be interested in, one lady owner....).
An important point here is that the standards are sometimes varied by different States and some are open to a teensy weensy bit of interpretation.
But if that was the only thing I got wrong I feel chuffed - as I wrote it I felt like I was doing a validation board (and that will give an idea of how long I've been doing ATC - and when I started I used loads of those old fashioned procedural separations!).
An important point here is that the standards are sometimes varied by different States and some are open to a teensy weensy bit of interpretation.
But if that was the only thing I got wrong I feel chuffed - as I wrote it I felt like I was doing a validation board (and that will give an idea of how long I've been doing ATC - and when I started I used loads of those old fashioned procedural separations!).
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safety case asks what is the point of radar separation. Well, I'll treat this as a serious question but I'm conscious that I might be being suckered in here!
Yep
PS - safety case, please tell me you're not a controller!!!!
Why ?
Yep
PS - safety case, please tell me you're not a controller!!!!
Why ?
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safety case, even though an awful lot of controlling these days is done with radar, it doesn't mean that a controller has to use radar separation all the time, there are other forms of separation that can be employed even if radar is available which is more expedicious which is all the answers you have above.
Basically, radar in the UK is normally 5 nm. This is extended to 10 nm where the airspace is deemed this is needed due to the distance from the radar heads. In the TMA's this can be reduced to 3nm if within 40nm of a radar head supplying the radar feed (think that's still correct?). However, we don't always achieve this. Radar separation is much closer than nearly any other form of separation so is used when available to gain the optimum for the a/c concerned. Simple?
Basically, radar in the UK is normally 5 nm. This is extended to 10 nm where the airspace is deemed this is needed due to the distance from the radar heads. In the TMA's this can be reduced to 3nm if within 40nm of a radar head supplying the radar feed (think that's still correct?). However, we don't always achieve this. Radar separation is much closer than nearly any other form of separation so is used when available to gain the optimum for the a/c concerned. Simple?