LHR Temporary Midhurst SIDs?
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to get a few percent increase in LHR movements
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A few quick points as I understand them.
Govt policy currently is to concentrate departures.
RNAV overlays of the existing SIDS would change the route as replication isn't possible. Therefore even 'doing nothing' things will change.
Those communities under the routes, if RNAV overlays of the existing SIDS is where this ends up, would experience concentrated overflight.
However by testing PBN track containment and 10' 15, and 21 degree splits, NATS and Heathrow are attempting to add respite to those communities by adding more routes, and sharing the traffic around them in a predictable way. I'd imagine this would be like the current arrival alternation on arrivals. These are the fair flight paths John Stewart refers to in my earlier post.
I find it amazing that HACAN and Heathrow are aligned on this. How times change.
Govt policy currently is to concentrate departures.
RNAV overlays of the existing SIDS would change the route as replication isn't possible. Therefore even 'doing nothing' things will change.
Those communities under the routes, if RNAV overlays of the existing SIDS is where this ends up, would experience concentrated overflight.
However by testing PBN track containment and 10' 15, and 21 degree splits, NATS and Heathrow are attempting to add respite to those communities by adding more routes, and sharing the traffic around them in a predictable way. I'd imagine this would be like the current arrival alternation on arrivals. These are the fair flight paths John Stewart refers to in my earlier post.
I find it amazing that HACAN and Heathrow are aligned on this. How times change.
RNAV overlays of the existing SIDS would change the route as replication isn't possible.
In fact that's exactly what has been done in the case of the easterly Midhurst SIDs (MID3J/3K).
Thread Starter
Anyone know WHY it is Government policy to concentrate departures?
As Zonoma says there is an awfully long way to go on this , and that was underlined at the public meeting I went to last night chaired by local MP. It was stressed many times that this was a performance data gathering trial not a new route trial and that no new routes could come in without Government approval and a lot of consultation and debate
The presenters , two from HAL and one from NATs were not great-one was pretty much Ok and admitted they had badly misjudged the actual impact on the Bagshot -Windlesham area a point reinforced by a succession of heavies droning over the local hall. they were ill prepared to deal with the very informed questions about climb performance, initial clearance altitudes and the fact that many people had almost monitored the whole trial on FR24 as well as Bagshot being about 500 ft higher than LHR .
Overall though I think both sides learned something and LHR said that if and when more trials were planned there would be a lot of upfront consultation and awaress .
The presentation of the issue was generally poor and took no account of the fact that this area includes a lot of airport workers including pilots and ATC types and retired of the same ilk. Equally there were some silly questioners who went on about sleepless nights to the clear bemusement of the HAL people as basically there aren't any and never have been in the last 40 odd years except the very occasional delayed departure.
They never actually explained why they chose to concentrate flights over an area that had a reasonable amount of traffic but which was not the main or dominant path used by the MID departures. There was a lot of talk about reducing angles between initial departure routes and they have certainly brought the MID and SAM routes a lot closer together in this area.
So -on the one hand the residents groups need to keep the extremists in check(complaints about night flights, claims there has never been any noise in Bagshot, how dare the EU mandate these changes etc in order to present a credible set of concerns but also HAL, NATS and the oft referred to as the driving force for this , the CAA need to sell the concept and handle the environmental issues a lot better than they did on this showing.
As Zonoma says there is an awfully long way to go on this , and that was underlined at the public meeting I went to last night chaired by local MP. It was stressed many times that this was a performance data gathering trial not a new route trial and that no new routes could come in without Government approval and a lot of consultation and debate
The presenters , two from HAL and one from NATs were not great-one was pretty much Ok and admitted they had badly misjudged the actual impact on the Bagshot -Windlesham area a point reinforced by a succession of heavies droning over the local hall. they were ill prepared to deal with the very informed questions about climb performance, initial clearance altitudes and the fact that many people had almost monitored the whole trial on FR24 as well as Bagshot being about 500 ft higher than LHR .
Overall though I think both sides learned something and LHR said that if and when more trials were planned there would be a lot of upfront consultation and awaress .
The presentation of the issue was generally poor and took no account of the fact that this area includes a lot of airport workers including pilots and ATC types and retired of the same ilk. Equally there were some silly questioners who went on about sleepless nights to the clear bemusement of the HAL people as basically there aren't any and never have been in the last 40 odd years except the very occasional delayed departure.
They never actually explained why they chose to concentrate flights over an area that had a reasonable amount of traffic but which was not the main or dominant path used by the MID departures. There was a lot of talk about reducing angles between initial departure routes and they have certainly brought the MID and SAM routes a lot closer together in this area.
So -on the one hand the residents groups need to keep the extremists in check(complaints about night flights, claims there has never been any noise in Bagshot, how dare the EU mandate these changes etc in order to present a credible set of concerns but also HAL, NATS and the oft referred to as the driving force for this , the CAA need to sell the concept and handle the environmental issues a lot better than they did on this showing.
Some you can, some you can't. RNAV SIDs are designed to different criteria than conventional SIDs.
But it's hard to imagine a set of manoeuvres involving radials, QDMs and height/climb/speed restrictions (which is a pretty good description of what a SID is) that couldn't equally be defined with fly-by fixes, tracks, level/speed constraints and path terminators (i.e. as an RNAV1 SID).
Which ones did you have in mind that can't ?
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Gonzo is absolutly correct, some conv SIDs can be replicated some can't. As no one in the UK has actually tried to replicate all the conv SIDs I have no idea which are replicable and aren't. It would cost quite alot to do that. I have been told by a procedure designer that it isn't possible and it's down to the actual PANS OPS criteria used to design RNAV procedures. I would bet that any conv SIDs that have sharp large turns would be tricky to replicate without the use of RF for example.
Going back to PBs question: "Why have MID & SAM Easterly SIDs initial tracks been changed to be the same?"
The official departure interval between conv SAM and conv MID SIDs is 3 mins, because the conv easterly MID SID ballons further east of the conv SAM SID track. If you make the initial SID tracks the same, as has been done with the trial RNAV SIDs, the departure interval may be reduced to 2 mins. Basically giving the TWR more flexibilty and decrease delays at the runway holding points.
Going back to PBs question: "Why have MID & SAM Easterly SIDs initial tracks been changed to be the same?"
The official departure interval between conv SAM and conv MID SIDs is 3 mins, because the conv easterly MID SID ballons further east of the conv SAM SID track. If you make the initial SID tracks the same, as has been done with the trial RNAV SIDs, the departure interval may be reduced to 2 mins. Basically giving the TWR more flexibilty and decrease delays at the runway holding points.
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With ref to Pax Brit comment above. When you talk about well informed questions, does that include the one where the questioner asserts that aircraft over Bagshot are closer to 300ft, yes 3 hundred feet, than the 5-7,000ft the panel suggests?
Indeed so.
Note the > 180° turn that forms part of the LAM1X SID (RNAV1 equivalent of the conventional LAM4M SID).
No RFs involved there, only TFs.
No RFs involved there, only TFs.
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I thought (feel free to tell me I'm wrong) that you could replicate conventional SIDs with RNAV, but due to the improvement in track keeping when PBN is used the actual result for residents won't be the same as with conventional SIDs.
For example, if you have a turn on a conventional SID aircraft will natrually disperse over a wider area, due to the "inaccuracy" of conventional navigation compared to RNAV.
With an RNAV SID every aircraft will follow a much narrower corridor (less dispersal) which means that even if you try to replicate the original SID track the new RNAV procedure will concentrate traffic into a smaller area. This in turn will concentrate overfligths (and therefore noise) to a smaller area. Cuasing more respite for some residents but leading to an increase in noise for the ones directly under the new corridor.
Obviously all the above could be a load of rubbish though.
For example, if you have a turn on a conventional SID aircraft will natrually disperse over a wider area, due to the "inaccuracy" of conventional navigation compared to RNAV.
With an RNAV SID every aircraft will follow a much narrower corridor (less dispersal) which means that even if you try to replicate the original SID track the new RNAV procedure will concentrate traffic into a smaller area. This in turn will concentrate overfligths (and therefore noise) to a smaller area. Cuasing more respite for some residents but leading to an increase in noise for the ones directly under the new corridor.
Obviously all the above could be a load of rubbish though.
Obviously all the above could be a load of rubbish though.
, but I'd say it sounds like a pretty reasonable summary of the effective difference between PBN/RNAV navigation and the conventional ground navaid-based equivalent.Those differences aren't specific to SIDs, that's just where they are more apparent.
And of course it's the ability to perform more accurate track-keeping that has been the driver for the recent trials, as previous posts have explained and with the effects on communities that have been noted.
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<<the questioner asserts that aircraft over Bagshot are closer to 300ft, yes 3 hundred feet, than the 5-7,000ft the panel suggests?>>
I've not been following this thread - too complex for an oldie. However, that sentence caught my eye. Back in the 80s(?) it was my misfortune to have to entertain members of a noise group together with their arrogant and stupid leader. He told me that aircraft were flying down Windsor High Street at 500 feet. I showed him the SSR labels on the radar which suggested that they were over 1000 feet higher than that. He announced to his cronies that I had "fixed" the radar!!! That's the sort of idiot one has to deal with.
I've not been following this thread - too complex for an oldie. However, that sentence caught my eye. Back in the 80s(?) it was my misfortune to have to entertain members of a noise group together with their arrogant and stupid leader. He told me that aircraft were flying down Windsor High Street at 500 feet. I showed him the SSR labels on the radar which suggested that they were over 1000 feet higher than that. He announced to his cronies that I had "fixed" the radar!!! That's the sort of idiot one has to deal with.
the questioner asserts that aircraft over Bagshot are closer to 300ft, yes 3 hundred feet, than the 5-7,000ft the panel suggests?
I have no idea where the OP got that idea from - there is a reference to tracking aircraft on FR24, and some having been noted at three thousand feet.
Heathrow Airport Trials Public Meeting ? 10th October 2014 | Surrey Heath Residents Blog
Last edited by DaveReidUK; 14th Oct 2014 at 07:31. Reason: typo
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<<Aren't all the holding stacks due to vanish with the introduction of "Point Merge"?>>
Looking forward to watching that!
Looking forward to watching that!
https://www.gov.uk/government/upload...assessment.pdf
3.34 It is understood that Point Merge will not be taken forward at
Heathrow due to the limitations on the use of vectoring.
Heathrow due to the limitations on the use of vectoring.
Not fair!
Even though the 'trial' has finished, the departures are still passing several miles to the west of us instead of overhead, thus making our evenings quiet and 'empty' except after about 10 pm when they do seem to pass overhead.
Even though the 'trial' has finished, the departures are still passing several miles to the west of us instead of overhead, thus making our evenings quiet and 'empty' except after about 10 pm when they do seem to pass overhead.
Last edited by chevvron; 11th Nov 2014 at 16:08.