UK CLASS D & CONTROLLER CAPACITY
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UK CLASS D & CONTROLLER CAPACITY
I realise that this question is bit like asking "how long is a piece of string", but here goes anyway!
In the UK we have Class D CTR/A's with considerably varying levels of activity, and proposals for more to come as well. So let us firstly discount the Gatwicks & Manchesters, and stick to those with fewer fixed wing ATMs. Say those with between 10,000 and 40,000 ATM movements per year, i.e. an average of between 2.0 and 7.8 movements per hour for an 14hr/day operation.
How many simultaneous VFR transiting aircraft should it possible for ATC to handle? Please include as many or as few caveats as you see fit.
Thanks.
In the UK we have Class D CTR/A's with considerably varying levels of activity, and proposals for more to come as well. So let us firstly discount the Gatwicks & Manchesters, and stick to those with fewer fixed wing ATMs. Say those with between 10,000 and 40,000 ATM movements per year, i.e. an average of between 2.0 and 7.8 movements per hour for an 14hr/day operation.
How many simultaneous VFR transiting aircraft should it possible for ATC to handle? Please include as many or as few caveats as you see fit.
Thanks.
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It might help to know who we are dealing with as your profile says nothing. Your question is almost impossible to answer because there are so many variables. You could have 10 VFR transits which would involve little work but you might have half a dozen which would involve much more.
If you only had VFR transits the string is going to be very long for the average ATCO. As soon as you have IFR traffic to integrate the capacity for VFR traffic is limited. To the letter of the law the ATCO is only required to provide traffic information to IFR and VFR alike, unless the IFR requests traffic avoidance, in which case the ATCOs workload can significantly increase.
Problem is that there are no VFR/IFR traffic separation standards published in the UK (case for Class C airspace?). Any ATCO who values his/her licence is going to provide something akin to IFR separation due to the advent of TCAS.
Have seen many cases of traffic information provided to both IFR and VFR, never heard a request for "traffic avoidance" from the IFR, ATCO provides a form of separation to ensure collision avoidance, next thing "TCAS RA!", ATCO suspended pending investigation, then wrapped across the knuckles for doing his/her job as per MATS Part 1, "should have known better" comes to mind as part of the investigation de-brief.
The bottom line, the ATCO restricts the number of VFR transits to keep workload manageable and cover his/her a**e. Don't shoot the ATCO he/she is having to play against loaded dice.
As "traffic avoidance" only appears to be mentioned in MATS Part 1 (not every day reading for most pilots) how many pilots operating IFR know about it, and what they are going to receive, often less than their TCAS is expecting?
Problem is that there are no VFR/IFR traffic separation standards published in the UK (case for Class C airspace?). Any ATCO who values his/her licence is going to provide something akin to IFR separation due to the advent of TCAS.
Have seen many cases of traffic information provided to both IFR and VFR, never heard a request for "traffic avoidance" from the IFR, ATCO provides a form of separation to ensure collision avoidance, next thing "TCAS RA!", ATCO suspended pending investigation, then wrapped across the knuckles for doing his/her job as per MATS Part 1, "should have known better" comes to mind as part of the investigation de-brief.
The bottom line, the ATCO restricts the number of VFR transits to keep workload manageable and cover his/her a**e. Don't shoot the ATCO he/she is having to play against loaded dice.
As "traffic avoidance" only appears to be mentioned in MATS Part 1 (not every day reading for most pilots) how many pilots operating IFR know about it, and what they are going to receive, often less than their TCAS is expecting?
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Originally Posted by TCAS FAN
ATCO provides a form of separation to ensure collision avoidance, next thing "TCAS RA!", ATCO suspended pending investigation, then wrapped across the knuckles for doing his/her job as per MATS Part 1, "should have known better" comes to mind as part of the investigation de-brief
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Many thanks for the replies so far, all very interesting.
So let's narrow down our "string" to the following - and some might say that it looks remarkably like Southend, not true as I'm looking to keep this as hypothetical as possible.
- a currently class G airport gets a "standard" Class D setup (Norwich being a recent example for shape and size)
- let's use round numbers of 10,000 ATM per year, 1,000 air taxi per year, 30,000 total movements per year
- ATMs tending to bunch into 3 waves per day, so there will be times of zero ATM/hour
- lets go summer CAVOK with the non-ATM traffic spread evenly 08:00 to 19:00 i.e. typical average 5 movements per hour, probably peaking at 15+ per hour.
In the replies so far the largest number mentioned is 10 aircraft. That doesn't seem like very many (and it was qualified with "VFR transits which would involve little work") when looking at the number of transits that could be requested were Southend or Farnborough be given the Class D that they are seeking.
As an additional point I understand the bit about controller capacity, but how much can frequency and equipment capacity come into it? Can two controllers work one frequency to increase capacity, or how else can capacity be increased?
Thanks.
So let's narrow down our "string" to the following - and some might say that it looks remarkably like Southend, not true as I'm looking to keep this as hypothetical as possible.
- a currently class G airport gets a "standard" Class D setup (Norwich being a recent example for shape and size)
- let's use round numbers of 10,000 ATM per year, 1,000 air taxi per year, 30,000 total movements per year
- ATMs tending to bunch into 3 waves per day, so there will be times of zero ATM/hour
- lets go summer CAVOK with the non-ATM traffic spread evenly 08:00 to 19:00 i.e. typical average 5 movements per hour, probably peaking at 15+ per hour.
In the replies so far the largest number mentioned is 10 aircraft. That doesn't seem like very many (and it was qualified with "VFR transits which would involve little work") when looking at the number of transits that could be requested were Southend or Farnborough be given the Class D that they are seeking.
As an additional point I understand the bit about controller capacity, but how much can frequency and equipment capacity come into it? Can two controllers work one frequency to increase capacity, or how else can capacity be increased?
Thanks.
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1.
"Can two controllers work one frequency to increase capacity"
possibly, yes.
Why would a unit want to though? Pay for an extra controller to deal with traffic that (if they aren't a LARS unit), they aren't getting any £ for?
My previous unit used to open up 'Radar 2' on occasion to deal with busy periods, sometimes split one ATCO working IFR inbounds and outbounds, the other 'dealing with' VFR (i.e. talking to them, and generally keeping them out of the way of the approach - co-ordinating transits when possible, but more often than not giving them routings through CAS that kept them away from the IFR stuff)
2.
“How many simultaneous VFR transiting aircraft should it possible for ATC to handle?” (qualified with "VFR transits which would involve little work")
X amount! If the transits involved 'little work' (for example crossing a portion of CAS not in the approach or climb out lane, at an altitude not getting 'in the way' of IFR) then quite a considerable number can be handled. All VFR, the ATCO only has to provide traffic info by means of 'separation'.
As someone mentioned above, once you get IFR traffic in the mix, can get more complicated.
Back to the length of your piece of string!
"Can two controllers work one frequency to increase capacity"
possibly, yes.
Why would a unit want to though? Pay for an extra controller to deal with traffic that (if they aren't a LARS unit), they aren't getting any £ for?
My previous unit used to open up 'Radar 2' on occasion to deal with busy periods, sometimes split one ATCO working IFR inbounds and outbounds, the other 'dealing with' VFR (i.e. talking to them, and generally keeping them out of the way of the approach - co-ordinating transits when possible, but more often than not giving them routings through CAS that kept them away from the IFR stuff)
2.
“How many simultaneous VFR transiting aircraft should it possible for ATC to handle?” (qualified with "VFR transits which would involve little work")
X amount! If the transits involved 'little work' (for example crossing a portion of CAS not in the approach or climb out lane, at an altitude not getting 'in the way' of IFR) then quite a considerable number can be handled. All VFR, the ATCO only has to provide traffic info by means of 'separation'.
As someone mentioned above, once you get IFR traffic in the mix, can get more complicated.
Back to the length of your piece of string!
Last edited by dan saaf; 22nd Jul 2013 at 09:01.
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Any application for the establishment or re-establishment of Class D will have to demonstrate the ANSP have the ability to maintain/man that Airspace. Any refusals will have to be logged at least for the first year.
Spliting the freequency would likely be in the form of Director (Approach) and LARS (in SEN case). That instantly creates the added capacity of the controllers to manage the traffic loading during peak periods and on those sunny CAVOK days.
In Southends case, increased staffing and procedures to split the frequency are already being developed whether or not the re-establishment of Class D is approved or not.
Class D provides a known environment. It shouldn't mean that any less traffic will have access if that is what you are getting at hypothetically.
Spliting the freequency would likely be in the form of Director (Approach) and LARS (in SEN case). That instantly creates the added capacity of the controllers to manage the traffic loading during peak periods and on those sunny CAVOK days.
In Southends case, increased staffing and procedures to split the frequency are already being developed whether or not the re-establishment of Class D is approved or not.
Class D provides a known environment. It shouldn't mean that any less traffic will have access if that is what you are getting at hypothetically.
