Point Merge - Dublin
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Believe they have reduced the use of holding in Oslo with 90%.
So yes, the system is very effective when there's a lot of traffic.
Little traffic on the other hand……
So yes, the system is very effective when there's a lot of traffic.
Little traffic on the other hand……
Join Date: Jun 2001
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Point merge is being developed in the UK too for LAMP (London Airspace Management Programme). The Gatwick model does allow for conventional holding, but at stacks further away from the airport, and at higher levels to allow the departures to also climb higher. I think the plan is to allow continuous climb to at least FL100. However, most "holding" is done in a linear fashion along pre-determined arcs closer to the airport, and then at the appropriate time to achieve the desired spacing, aircraft are cleared for an RNAV transition for the approach and fly themselves onto the ILS without much (radar) intervention from ATC.
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<<cleared for an RNAV transition for the approach and fly themselves onto the ILS without much (radar) intervention from ATC.>>
OK K. How is the required spacing achieved if not by ATC?
OK K. How is the required spacing achieved if not by ATC?
Join Date: May 2006
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in dublin's case the area sectors now aim to deliver aircraft to approach 8nm in trail at 230knots (descending to the same level). previously traffic could, and frequently was, just lamped towards the hold vertically separated. more cooperation is also now required from scottish and london to stream traffic in order to make the system work.
dublin's point merge was introduced in the depths of winter and hasn't seen proper summer traffic yet, but the stack has already occasionally been used when surges hit. claims that it has "reduced holding" ignore the fact that delays are now imposed by slowing everyone down, and of course flying the arc.
the arc itself forces less enthusiastic controllers to take aircraft out of the hold sooner than they might like if using vectors, but for controllers who like to maximise use of their airspace it's seen as very inefficient. a plain old lie being flogged by it's backers is that it allows continuous descent approaches, but the fact is that point merge requires aircraft to be level by the hold, and not given descent until turned off the arc for the localiser. again, an approach controller who knows what they're up to can give a fairly accurate distance to touchdown on initial contact or when starting vectors and actually provide a cda.
in brief, cooperation from surrounding units and area sectors in streaming arrivals has been effective and may have been all that was required, rather than the literally millions of euro (allegedly) and number of years poured into something that the actual users (pilots and controllers) aren't particularly impressed with.
dublin's point merge was introduced in the depths of winter and hasn't seen proper summer traffic yet, but the stack has already occasionally been used when surges hit. claims that it has "reduced holding" ignore the fact that delays are now imposed by slowing everyone down, and of course flying the arc.
the arc itself forces less enthusiastic controllers to take aircraft out of the hold sooner than they might like if using vectors, but for controllers who like to maximise use of their airspace it's seen as very inefficient. a plain old lie being flogged by it's backers is that it allows continuous descent approaches, but the fact is that point merge requires aircraft to be level by the hold, and not given descent until turned off the arc for the localiser. again, an approach controller who knows what they're up to can give a fairly accurate distance to touchdown on initial contact or when starting vectors and actually provide a cda.
in brief, cooperation from surrounding units and area sectors in streaming arrivals has been effective and may have been all that was required, rather than the literally millions of euro (allegedly) and number of years poured into something that the actual users (pilots and controllers) aren't particularly impressed with.
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Many years ago, a trial of this sort of thing was conducted an an airport close to the foot of Mt. Belzoni.
One of the locally-based operators went to the ATC Ops department and said "our new 757s have got this spanking-new new RNAV kit and we can get from the holding-fix to the ILS without the help of approach radar".
"Very good" said ATC Ops, "We'll design a procedure for it and organise an operational trial".
Subsequently, ATC Ops were as good as their word and came up with procedures based on 4 intermediate waypoints, MELLA, ETLEY, BUSBY and TRAFA. Somewhere, I still have a copy of the TOI detailing said procedures.
They worked OK, provided that the A/C flying them was the only one around. Several successful profiles were flown 'a la nocturne', sadly, during the day, when other planes were around, very few were accomplished.
ATCO Two, how can holding be linear if it occurs along an arc? Unless you are implying that an arc is composed of an infinite number of linear segments, which of course it is.
One of the locally-based operators went to the ATC Ops department and said "our new 757s have got this spanking-new new RNAV kit and we can get from the holding-fix to the ILS without the help of approach radar".
"Very good" said ATC Ops, "We'll design a procedure for it and organise an operational trial".
Subsequently, ATC Ops were as good as their word and came up with procedures based on 4 intermediate waypoints, MELLA, ETLEY, BUSBY and TRAFA. Somewhere, I still have a copy of the TOI detailing said procedures.
They worked OK, provided that the A/C flying them was the only one around. Several successful profiles were flown 'a la nocturne', sadly, during the day, when other planes were around, very few were accomplished.
ATCO Two, how can holding be linear if it occurs along an arc? Unless you are implying that an arc is composed of an infinite number of linear segments, which of course it is.
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It looks as though 'point-merge' will produce more CO2 than existing ATCO-centric procedures, leading to that much-trumpeted global rise in sea-level.
Then we'll all be dependent on an ark.
Then we'll all be dependent on an ark.
Last edited by ZOOKER; 24th May 2013 at 20:59.
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OMG Zooker, sounds like the Concorde Standard Approaches into Heathrow. They worked as long as nobody else was about because you never knew when it was going to turn. The BA bloke who thought it up got a prize of more money than an ATCO earned. After a while the crews got fed up with it and I recall an old buddy of mine, who went on to become a senior chap in one of the Channel Islands, saying to Concorde one day: "Do you want a standard approach or a hand-job?" There was no contest and we did all the approaches thereafter.
Last edited by HEATHROW DIRECTOR; 24th May 2013 at 21:16.
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Having looked at the theory it would seem that point merge would allow the process to be computerised to some extent.
With arrivals roughly sequenced by Flow Management it would be straightforward for a computer to manage the approach sequence using point merge. A bit of data linking would be needed, of course.
With arrivals roughly sequenced by Flow Management it would be straightforward for a computer to manage the approach sequence using point merge. A bit of data linking would be needed, of course.
point merge
Sounds like another scheme emanating from non-ATCOS, or incompetent (non-operational) ATCOs, or other bodies who know little or nothing about ATC, to take what's left of the fun out of the job & impose another new solution to "problems" which are NOT problems.; or which will not be solved by procedures & systems which cause more problems & delays than the systems they replace.
Echoes of "Tunnels in The Sky".
I'm glad I was in ATC when I was & not in today's technocratic age!
Echoes of "Tunnels in The Sky".
I'm glad I was in ATC when I was & not in today's technocratic age!
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The BA bloke who thought it up got a prize of more money than an ATCO earned.
it would be straightforward for a computer to manage the approach sequence using point merge
aircraft without datalink capability;
non-prnav aircraft;
any other aircraft outside a certain performance window;
go-arounds;
emergencies;
anything else the project team aren't bothered with simulating accurately before implementation.
cooperation from the weather gods in keeping the airspace on this windswept east atlantic rock clear of cb activity would also be useful, but unlikely.
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BTW, what happens if for some reason an aircraft reaches the end of the arc? Is the merging point the next waypoint, so all aircraft in all arcs start to converge? Hopefully without approach clearance and on different levels. 
(yes, I'm aware that such situation should be prevented in normal circumstances.)
(yes, I'm aware that such situation should be prevented in normal circumstances.)
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the next point after the end of the sequence leg is way off on the other side of the localiser. obviously. it's not known as pointless merge / plane merge for nuthin'. looks wonderful in computerfied simulation replays, but if you're the muppet left holding the bag when the sequence legs are getting stuffed you probably don't have time to appreciate the beauty of planes going every which way that you're not really in control of.
Eurocontrol has some interesting video clips of simulations, but I am struggling to see any advantage other than as there are predefined tracks and waypoints then for much of the time the controller is relieved of assigning specific headings. And it assumes that there is sufficient elbow room to stream the aircraft anyway - which, presumably could be done with current techniques?
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