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Near miss over East London

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Near miss over East London

Old 16th Aug 2007, 21:59
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slip and turn,

Very much appreciate the trouble you've gone to Roffs but the fact remains that laterally the LHR inbound and LCY outbound tracks overlap all the time, and the adjustments I thought I was seeing weren't much to do with the various joins but all occurred around the final 180 degree turn sector.
The LCY departing traffic follows pretty much the same track all the time because it's on a SID, there will be deviations but only small ones.

The LHR traffic will fly over quite a wide area. Sometimes it will fly directly over LCY departing traffic, sometimes it will fly east of the LCY departure, sometimes it will fly west of the LCY departure. At all times it will be vertically separated from the LCY traffic until such times as it's at least 3nm laterally from either the LCY SID track or from a specific LCY departure if there's one airborne. Only at that point (3nm lateral sepn) will it be descended further.

I'll say it one last time, yes the LCY deps and LHR arrivals overlap but the path that you see the LHR arrival fly has absolutely nothing to do with where any LCY departures are and all to do with sequencing on to final at LHR. There is no interaction or co-ordination between the two sets of controllers required under normal circumstances, it's all taken care of by each set of controllers following specific procedures.

There's little more I can say, that's the way it works. Accept or not as you wish

Sorry, I don't have any more track plots but if you google the various noise monitoring web sites for each airport they might have some on-line.

splitduty and taffy1, thanks
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Old 16th Aug 2007, 22:04
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slip and turn,

Why take potshots at the messenger ? I am sure that's not what Roffa intended when he asked for backup, or do you know better?
You seemed to be questioning my explanation of the way traffic is handled in that area, that is all. I know how it works...

The only contentious opinion I have given (I think?) is that vertical separation alone in this uniquely busy corner seems to push up the chances of an error.
Believe me when I say that this scenario is by no means unique in the London area. Arrivals and departures are crossing each other at minimum vertical separation hundreds if not thousands of times a day.

It doesn't matter how quickly traffic out of LCY reaches 3,000ft as long is it doesn't bust it because there's no guarantee of lateral separation at any time. LCY deps or LHR arrivals level busting in that area are very infrequent.
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Old 16th Aug 2007, 22:08
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Thanks again Roffa

I'll say it one last time, yes the LCY deps and LHR arrivals overlap but the path that you see the LHR arrival fly has absolutely nothing to do with where any LCY deparatures are and all to do with sequencing on to final at LHR.
Got that the first time - if you were reading anything more into it, then I was just toying with the notion of how many occasions the two controllers might need to liaise on a shift, but you've kindly answered that too.
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Old 16th Aug 2007, 23:49
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<<The only contentious opinion I have given (I think?) is that vertical separation alone in this uniquely busy corner seems to push up the chances of an error.>>

Is RVSM a real concern in your life as well? Perhaps you could give us an expert opinion of 1000' vs. 2000' vertical separation in the en-route environment with PRNAV 0.3nm able aircraft.
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Old 17th Aug 2007, 07:45
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Go to http://lhr.webtrak-lochard.com/template/index.html and set the start time as 0940. Set the zoom out to maximum. AC866 (a 767) is in the Bovingdon hold. If you hover over the aircraft it gives various data items. You have to keep moving your mouse off the icon and then back on to refresh the data. You can't see all the altitude for the critical time (the data tag moves off the viewable area) but he does seem to bounce back up to 4k as he turns finals.
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Old 17th Aug 2007, 08:16
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The last readable altitude on the AC is down to about 3300 over Canary Wharf (may have gone even lower off screen) before climbing back up to 4000!
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Old 17th Aug 2007, 09:10
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Originally Posted by tom775257
Is RVSM a real concern in your life as well? Perhaps you could give us an expert opinion of 1000' vs. 2000' vertical separation in the en-route environment with PRNAV 0.3nm able aircraft.
Not especially, no, but if you see some relevance then perhaps you could enlighten us, tom?
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Old 17th Aug 2007, 09:42
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In Summary

1-Vertical separation is the only thing that is enforced between LCY and LHR tracks.
2-There was none in this case.
That leaves me wondering why all the ATC chaps on here did not say
"Yes, we know about that it was a level bust" , instead we seem to have pages of discussion telling us that it did not happen. Scary.
Of course if the LCY pilot had been equally bad at sticking to his assigned level he would have passed above this AC plane with a bigger separation than they had in this case. (3700 , 3300) versus (3000, 3300) .
Actually the tracking SW shows 3369 as the minimum. If you select the tag contents by left clicking on it and dragging the mouse over the data then you continue to see the values even when they go off the side of the screen.

Last edited by paull; 17th Aug 2007 at 10:04. Reason: Added better reading
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Old 17th Aug 2007, 12:53
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Oi, who's using my screen shots?

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Old 17th Aug 2007, 13:15
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<< Go to http://lhr.webtrak-lochard.com/template/index.html and set the start time as 0940. Set the zoom out to maximum. AC866 (a 767) is in the Bovingdon hold. If you hover over the aircraft it gives various data items. You have to keep moving your mouse off the icon and then back on to refresh the data. You can't see all the altitude for the critical time (the data tag moves off the viewable area) but he does seem to bounce back up to 4k as he turns finals.>>

If you RTM, you'll see you can leave the flight detail tags on.
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Old 17th Aug 2007, 13:41
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paull,

1-Vertical separation is the only thing that is enforced between LCY and LHR tracks.
2-There was none in this case.
That leaves me wondering why all the ATC chaps on here did not say
"Yes, we know about that it was a level bust" , instead we seem to have pages of discussion telling us that it did not happen. Scary.
Can you point out where I or anyone else said the incident in question did not happen?

I was responding to (incorrect) assumptions about the way the airspace in the area is managed in order to try and clarify things for at least one contributor to the thread.

I have no first hand knowledge of the incident in question as I wasn't working when it apparently happened so have refrained from commenting on any specifics and if I did have inside knowledge of a specific incident it's unlikely I'd share it here to any great extent anyway.
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Old 17th Aug 2007, 14:19
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From the lhr.... website:

AC866 goes down to 3369 feet displayed on base leg before coming back up to 4232 feet shortly before intercepting.

Taken from the succeeding 747: 3925 feet displayed equals 4000 ft QNH, so the lowest of AC866 was around 3450 ft QNH.

While Mode-S altitude resolution is 25 feet (Mode-C 100 feet), where do these altitude data come from?
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Old 17th Aug 2007, 15:12
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From this thread, in Summary for LHR and LCY pilots
1-Vertical separation is the only thing that is enforced between LCY and LHR tracks.
2-There was none in this case.
3-LHR 27 approach traffic be extremely careful not to sink and bust 4000 in vicinity of LCY
4-LCY 28 departure traffic be extremely careful not to climb above 3000 same vicinity.

...even the BA behind the Air Canada is right on the limit according to Webtrak.

For LHR/Thames ATC
Know of any other major hotspots worth discussing in the interests of safety?

Last edited by slip and turn; 9th Sep 2010 at 19:17. Reason: After 3 years I got sick of looking at the LHR28 typo which now reads LCY28
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Old 17th Aug 2007, 15:12
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....it aint what what you say its the way that you say it..

Roffa
Can you point out where I or anyone else said the incident in question did not happen?
I guess the answer is no, if I look at exactly what was said, perhaps I should have said I was left with the impression that you were saying S&T was not only technically wrong, but you were also dismissive of the point being made which was (to my mind)
Quote:
The only contentious opinion I have given (I think?) is that vertical separation alone in this uniquely busy corner seems to push up the chances of an error.
To which the reply was
Believe me when I say that this scenario is by no means unique in the London area. ....level busting in that area are very infrequent.
I just think that the professionals on this thread are missing the opportunity for a productive discussion here along the lines of:
Is there any way from an ATC standpoint that we can do better in this particularly busy spot?
I would also feel happier if I felt that ATC folk could immediate check on all level busts, that way I would feel happier that they were systematically captured, and then I might feel more confident that they are rare. For example, if your first reply had started
"Yes there was a level bust 8:48am....."
then I for one would say "Good these guys are on the ball" It is difficult when you sell a service, particularly one of which the ultimate end client has little visibility, to reassure people that the service is good. I think ATC needs some PR!
Busts will appear very rare if we only count the ones that get noticed, but I have no idea of the technology implemented so I will just hope that it is comprehensive in its data capture (historically) and effective in its ability to avert disaster (real-time).
As I read the numerous threads on Pprune, I am surprised the significant number of pilots (particularly the less experienced ones) who think they know it all. It is a little worrying, but it seems that most grow out of it. On the ATC side, I see no such equivalent of the over-confident cowboy (thank heavens) I do however sense a significant defensiveness of attitude, and the fact that your pals in the playground ran over and jumped in so quickly, just reinforces for me this sense of "we are being victimised". What you said was correct, but If I were "slip and turn" , I would feel as thought I was getting a hard time.
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Old 17th Aug 2007, 15:57
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paull,

My first reply was unlikely to ever start "yes there was a level bust at time whatever..." as I'm not at work 24hrs a day 365 days a year and so don't know about every single level bust that takes place either in the airspace I work or the wider TMA and I also don't consider it my place to necessarily confirm or deny anything that's reported here from apparently someone listening to a scanner.

S and L was wrong in his assumptions about how traffic is handled in that area... I wasn't looking to give him a hard time, merely trying to get over the correct information which to start with didn't appear to be being accepted. I wasn't offering any opinion on the reported level bust that started the thread, just clarifying basic procedures used in the area.

I'll say this again, the interaction between LCY deps and LHR arrivals is not in any way unique in the TMA. Arrivals and departures are crossing in similar circumstances (minimum vertical separation, no lateral separation) in and out of every London airport.

NATS is very much aware of the level bust issue and spends a great deal of time and effort on the subject, forgive me if I think there are better forums and ways for tackling the wider issues than PPRuNe.

I'm not here to give anyone a hard time, nor do I feel ATC is victimised or overly defensive. I will however do my best to correct anything that I know to be incorrect but not necessarily comment on any particular incident.

Finally, if you want more info on NATS and level busts, have a look here... http://www.levelbust.com/
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Old 17th Aug 2007, 16:11
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@Paull, ATCOs at West Drayton (currently where the TC sectors, and the major London airports Approach Control Service Units are situated) do the best job possible in such a busy piece of airspace. Vertically is the best way to maintain separation and laterally is generally the best way to create separation. Obviously, in such busy airspace like the LTMA this is not always the case, but certainly in inter-TMA aerodrome separation it is. Although you might already understand this, I will give you a specific extract from the current SID charts for the SAM departures from LCY off 28:

SAM4T
LON D23 at 3000' (6.1%)
LON D27 at 3000'
LON D31 at 4000'
DET VOR at 4000'.

As you can see, they climb initially to 3,000ft. Until they are past 27DME from LON (London VOR) they cannot climb any further. Once past 27DME, they can climb to 4,000ft, which they must reach by 31DME from LON. Now, just as a reference for you, in a normal (if that applies in TC) day, at any given time, aircraft inbound LHR would not normally be below MSL there, which is dependant on the QNH, but is no lower than FL70. As you can see, plenty of separation in that part.

At the real ATCOs in TC, correct anything I stated incorrectly, I'm sure there might be something.... because I seem to be one of the only people that recognise I'm not a real ATCO anywhere, let alone in TC and I don't know everything
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Old 17th Aug 2007, 17:16
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As a regular SLF at LCY I'd just like to say thanks to all the contributors as this has been most interesting and I have to say slightly unnerving.

As an aside on the 6th of August I was inbound to LCY and as the aircraft turned onto base I observed a light aircraft pass under the Dornier offset approx 250" and below by slightly more, couldn't comment on the slant range but it was quite alarming, but as they say, what's hit is history what's missed is mystery......won't stop me flying from LCY but something else to ponder of course.

rgds

glad rag

ps what's a "RJ" they sound cool although the Scot Air Dorns don't hangabout either.
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Old 17th Aug 2007, 17:46
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gladrag,

If you were landing on 28 at LCY you'd likely have been at 3,000ft as you joined the ILS.

The base of controlled airspace in that area, before reaching the LCY control area and zone, is 2,500ft so you can have light aircraft operating at 2,499ft there and not talking to anyone as the airways traffic flies over them at 3,000ft.

It's quite common all round the London area where IFR traffic inside CAS descends to 500ft above the base of controlled airspace with unknown traffic operating 501ft below i.e. up to just below the airspace base and not talking to anyone.

If landing on 10, inside the Class D of the LCY control zone or control area there's no actual separation required between IFR (airways) and VFR (light aircraft) assuming both are talking to ATC, just traffic info and visual avoidance according to the rules, though ATC will tend to build in a certain amount of vertical or lateral but not necessarily 1,000ft or 3nm.

RJ is a Regional Jet, BA146 as was.
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Old 17th Aug 2007, 17:47
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Three things happened which I can think of:

1. The aircraft you were on, left CAS, highly unlikely I think on a base to land at LCY.

2. That aircraft entered CAS without clearance, or got clearance, but was just a prat and went disregarding ATC traffic information.

Third, is again highly unlikely, for the fact that I doubt, unless you were on a very long base, there's not any CAS down to the SFC (which would mean your outside definitely outside the CTR) and the ATCO descended the aircraft close, or down to the border of CAS (again, unlikely IMHO - certainly if he is aware there is other aircraft down there outside CAS) and the other guy was operating very near the base of CAS.

My thoughts are no.2 - someone busted the CTR / TMA.

EDIT: Got beaten too it (atleat one of my suggestions is in there as the correct answer )
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Old 17th Aug 2007, 18:19
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Thanks for those replys they sure cleared things up in my mind,

Hmm......

does this controlled airspace height restriction remain at 2500 all the way to the airport boundary or does it follow the glidepath down?

thanks again

glad rag
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