Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Near miss over East London

Tech Log The very best in practical technical discussion on the web

Near miss over East London

Old 18th Aug 2007, 12:31
  #61 (permalink)  
Join Date: Jun 2007
Location: Cardiff, UK
Posts: 51
Likes: 0
Received 0 Likes on 0 Posts
There is still nothing dangerous about that particular part of airspace. You do realise that even at places like Cardiff, they sometimes bring aircraft under / over each other with only a 1,000ft of seperation?

It is more than a safe standard to separate aircraft by - level busts happen, and no matter where they happen, it's dangerous. But that doesn't mean that we shouldn't use 1,000ft sep. Regarding, "tough questions", I don't believe your questions are tough to answer at all - they have been answered by the ATCOs, and they stand by, and still don't see what the problem is - funnily enough because a problem doesn't exist.

If your going to be like that, why don't we have aircraft not lining up on a runway as another departs, why don't we scrap the "land after" clearance, etc... get real. These things are perfectly safe - just like the vertical seperation. In the UK, safety is paramount. If there was a problem, why wouldn't the authorities do something about it? Not everyone in aviation is out there just to make money. In fact, we go beyond ICAO requirements. We are "that safe". For example, our minimum wake vortex seperation is usually greater than ICAO values (category depending), we use modified ICAO RTF and list the modifications in the back of CAP413 with the explanation always being from a safety stand point. Why do they do all these things and more, and yet leave a "hotspot" in LTMA airspace alone? Sure, it maybe a hotspot - but then vertical seperation ensures things are kept safe. At the end of the day - the CAA CANNOT get rid of human factors. Nothing can be done short of absolutely destroying British aviation... because that's what would happen if we start applying massive amounts of seperation both vertically and horizontally. The LTMA would just break down

Now, let me ask you my question. What do you think should be done? Bearing in mind, this new option has to ensure the same expeditious movement of aircraft at the moment. I think you will find that the solution has already been implemented.
gone_fishing is offline  
Old 18th Aug 2007, 13:35
  #62 (permalink)  
Join Date: Mar 2007
Location: In my head
Posts: 694
Likes: 0
Received 0 Likes on 0 Posts
Good afternoon Gone_Fishing ! Hope you slept well, growing lad needs his sleep !

I am sorry about the sharp put down last night but my feeling was that you were allowing your confidence to get in the way of basic good manners.

With your obvious application to your studies so far, you undoubtedly have a career in aviation to look forward to, but do wake up to the fact that people who might not wish to make a thing of it might have "been there done that" eons ago and they have might also have complimented their knowledge by the study of or by working in a completely different field.

Take a look at that TAM/Congonhas thread again. You'll see some real pros at work there biting their tongues so hard that they must hurt, and opening their minds to all kinds of uncomfortable hypotheses and revelations. You'll see for example PBL leading a sizeable chunk of the discussion. In aviation credential terms he was just a PPL when he started offering views on commercial aviation safety, but of course, he developed his interest over many years and steadily built up his credibility so that he is now a world-leading academic on an extremely important subject. You will notice how responsibly most posters are conducting themselves over there. People died and that alone demands reverence.

As Spitoon or Roffa said, this thread here has become obscure in PPRuNe.
Reasons might include:
1. The near miss analysis isn't any where near as baffling as Congonhas, and
2. It simply hasn't generated much interest due perhaps to some irreverence, indifference, some possibly boring denial (on both sides of the argument), veiled insults and perhaps my bad attempts at breathing some life into it.

I do take responsibility for my part in degrading the discussion. I was biting my tongue, but then I yielded to repeated goading. I am weak !

When you study a subject you love as hard as you have G_F, it becomes second nature to recall pages and headings and sentences and bullet points and jargon. Trust me, it really does. And you can get straight As in all your exams that way including all the aviation exams. I remember doing the same. I wouldn't do it differently. You feel very good about it. I always do. Many people actally pass exams but never get the feeling they are completely in command of a subject so far .... in a way they are life's true achievers when they ultimately do get to command very important things.

For those that find exams easy and those that find them hard, the real knowledge will come later when you apply and experiment with what you learned from books, "annotate it in the margins" so to speak with your own observations, and then balance the whole lot of it with other worlds around yours.

My apologies again for the put down. I hope you understand a little of why I weakened and tried it.

Now look what I've done ... the thread is way off topic and perhaps without hope of recovery ...

You ask me what I would do, and suggest that a solution has already been implemented.

Well, a very long time ago I was given a definition of the word "Management". It is not the only definition of course but I suggest it is still good for some problems in ATManagement as well as any other ... it is this "Management is the ceaseless pursuit of small improvements"
One possible foil to that of course is "If it ain't broke don't fix it"

Last edited by slip and turn; 18th Aug 2007 at 14:05.
slip and turn is offline  
Old 18th Aug 2007, 14:08
  #63 (permalink)  
Join Date: Jun 2007
Location: Cardiff, UK
Posts: 51
Likes: 0
Received 0 Likes on 0 Posts
No problem sir. I do also owe you an apology. I over stepped my mark, for which I regret.

Back on topic:

I see some of things you are saying in the fact that you wish for the NATS management and perhaps the CAA to discuss alternate means of providing seperation and a back-up in case seperation degrades (am I sort of along the lines?). The only problem I see is that it's very difficult to implement anything other than is in place, because there must be a balance between safety and expeditious movement of traffic - and I think NATS has that down to a detail.
gone_fishing is offline  
Old 18th Aug 2007, 15:20
  #64 (permalink)  
Join Date: Mar 2007
Location: In my head
Posts: 694
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by G_F
I see some of things you are saying in the fact that you wish for the NATS management and perhaps the CAA to discuss alternate means of providing seperation and a back-up in case seperation degrades (am I sort of along the lines?).
Well yes if you like, that's part of the "ceaseless pursuit of small improvements" in general terms that I guess has yielded initiatives like Level Best and the AP Set Altitude Mode S downlinks for example. But there isn't much evidence that either of these initiatives helped in this case.

You are right, airspace design changes are no doubt hugely problematical and expensive to test and certify, just like introducing new airframes.

For example, simplistically, the STAR procedure that brings LHR traffic in over the LCY SID might be raised 500 feet or more at that point just to build in an extra buffer - in practice such a change might not exclude too many actual paths, but I don't know. Even if it were possible, such a change would have some knock-on effect perhaps in controller workload or cockpit workload whilst LHR traffic establishes on the localiser and extended glidepath whilst simultaneously managing the little "hump" I have just introduced and the slightly now more hurried need to manage speed o the extended glidepath.

I emphasise that my last paragraph is undoubtedly simplistic. But if not overly so, then perhaps the extra workload could in turn be alleviated by special ATC discretion to authorise earlier decent when LCY wasn't moving. But then we are already told that ATC prefer to keep things separate(sic) vis-a-vis LCY and LHR for tried and tested general reasons. LHR are not interested in information about LCY traffic. That's Thames' bag. Or maybe some of the problems couldn't be improved by use of ATC discretion because very often both procedures are simultaneously at peak activity anyway.

I am sure a lot of what ATC have to do is a bit like 100 per cent successfully threading the proverbial camel over and over again several times a minute without blinking, so I do understand their reluctance to wet their thread/camel just because I suggested it !

So then for experts whose job it is to already have considered these things, it might boil down to a question of proceeding with new downlinks / back up systems, plus the more general Level Best awareness campaign, all glued together with the assertion that for the moment the current procedures ain't broke very often at all. That seems to be what we are seeing from the 4 ATCO contributions.

We know it ain't perfect. This incident shows one place where it might be a bit threadbare.
slip and turn is offline  
Old 20th Aug 2007, 17:35
  #65 (permalink)  
Posts: n/a
I flew into LHR that morning.After we landed an Aircanada landed after us.
The controller then on the ground frq informed the AC pilots that a report was going to be filed after their level bust.

I't wasn't that professional to say something like that on an open freq.They should have called thier agents or contacted them by telephone.
Old 20th Aug 2007, 18:48
  #66 (permalink)  
Join Date: Feb 2004
Location: Karup, Denmark
Age: 70
Posts: 175
Likes: 0
Received 0 Likes on 0 Posts
It wasn't that professional to say something like that on an open freq.
Not so fast, Gattaca. Maybe procedures say ATC must deliver this information ASAP, open frequency or not. "They" will find out anyway. I find it fair to the pilots, that they know something happened, that warranted a report. And very sensible to wait till they were on the ground.
normally right blank is offline  
Old 25th Aug 2007, 19:20
  #67 (permalink)  
Posts: n/a
Sorry, I've been having to work for my living the last few days but I've also been thinking about thius thread and, in particular, slip and turn's comments.

Responding to no particular earlier comments, perhaps it's important to remember why we separate aircraft - it's essentially to stop them banging into each other. Separation standards have a 'margin for error' built into them, certainly to take account of the accuracy of the instruments that are used to provide information about the relative position of the aircraft being separated but, I feel fairly sure, to provide a buffer for when us humans make errors. We are conditioned, perhaps more so in the case of controllers than pilots, to achieve separation rather than avoid collisions, but ultimately the latter is the event/situation that all of the rules are designed to avoid.

In the case that we are talking about it looks like some of that buffer was used - but the aircraft did not collide. We now have to learn from the event and see if there is something we can do to prevent recurrence - but, sometimes, it's just human error that is out of character for someone highly trained and competent in what they do and, as yet, we (or the pshrinks) don't understand the causes or how to stop it happening. Of course, if it is part of a series of errors that may indicate a deterioration in competence there are things that can, and should, be done.

Thinking about this, if we increased the vertical separation used in this piece of airspace - and, presumably, all other pieces of airspace which share the same hazards and risks - to 1500ft as suggested, what would the reaction be in the event of a level bust? To suggest increasing the separation to 2000ft??? In all probabaility (because there are lots of other barriers in the system) the outcome of the level bust would be the same - the aircraft do not collide but we use up some of the buffer that is built into the system.

Thinking now specifically of s and t's analogy between airspaces and airframes. Yes, I remember the picture of the 737 with the lid rolled back like a sardine can and I certainly know about the fatigue problems in the DH Comet. In the airframe/airworthiness world things changed after both of those issues were recognised. In very simplistic terms, after the DH Comet crashes we got round windows and after the Aloha Airlines 737 incident the inspection regime for older airframes was substantially. These changes came about because we learned from what had gone wrong - and took actions to prevent recurrence.

Although I have no connection with NATS I feel fairly confident that the organisation is learning from all incidents that occur and taking measures to prevent recurrence. It is important also to recognise that the environment is continually changing. ATC now routinely uses tools to monitor separation achievement far more closely than has happened in the past. As I tried to indicate earlier, this is partly mitigation against increased risk because of higher traffic densities, and to identify any systemic 'hotspots' (that are then 'managed').

So, overall, whilst I understand that an incident may cause concern, I see no reason to be concerned that there is a hotspot that is being ignored in that particular piece of airspace.
Old 16th Apr 2008, 14:04
  #68 (permalink)  
Join Date: Mar 2007
Location: In my head
Posts: 694
Likes: 0
Received 0 Likes on 0 Posts
Apologies in advance if reinstating this thread really is tiresome to those i/c ...

I don't scan this bit of London sky anywhere near as continuously as those in charge, (or anywhere near as often as some of my critics think I do ) but since it is one bit of England's sometimes blue and pleasant sky out of a handful which I often stare into when I am seeking inspiration, I sometimes can't help noticing aircraft movements in it ...

Despite my now infamous typo on 17-Aug-07 I think we established last time that the LHR 27 inbounds when turning and descending south over over Canary Wharf (if that's where they happen to be vectored) were never supposed to decend below 4000 until south of LCY 28 extended RWY centreline?

I saw one recently that looked a bit low, with the proverbial opposite track LCY departure in the same bit of sky albeit below by some margin, and so I in the fullness of time I checked Webtrak. Sure enough I found one at about the right time which seems to have dropped to 3907 or something when abeam LCY. Webtrak doesn't show the LCY traffic unfortunately.

Most on Webtrak if vectored this way seem to be at least 500 above that and often a lot more.

I am sorry it rubs some of you ATC folks the wrong way, but I haven't gone trawling through hours and hours of Webtrak to find this, so surely breaches(?) like this should not still be happening?

Edit: Oh dear, I left Webtrak running while I was typing this and when I went back to it I noticed something else slightly odd ... a different aircraft which I had marked as inbound had apparently reappeared from the West and appeared to be more or less glued to 3914 while it stooged around while (I guess) some poor ATCO was bravely trying to fit it in with the traffic coming off LAM north of the river - maybe it was a Go Around? But the point is that it was stooging around at 3914 (according to Webtrak) in that sensitive bit of airspace we discussed in this thread i.e. north of the LCY 28 extended centreline and finally crossed it at about the same reported sub-4000 altitude...

slip and turn is offline  
Old 16th Apr 2008, 14:32
  #69 (permalink)  
Join Date: Mar 2008
Location: Malvern, UK
Posts: 425
Received 1 Like on 1 Post
QNH corrected?

Don't know much about Webtrak but unless the altitudes are QNH corrected (unlikely I suspect) they can be out by a significant margin (easily a hundred feet and often more). Perhaps you should post an ATC thread rather than a Tech Log one so that those ATC guys can put you straight.
Dont Hang Up is online now  
Old 16th Apr 2008, 14:34
  #70 (permalink)  
Join Date: Oct 2000
Location: Berkshire, UK
Age: 79
Posts: 8,268
Likes: 0
Received 0 Likes on 0 Posts
Aircraft MAY be descended below 4000ft in that area under certain conditions so it is not a rule set in concrete.

Webtrak and SBS do not take account of the relevant QNH setting so the height you see indicated on your screen will almost certainly not be the correct one - in fact it may be many hundreds of feet out when aircraft are below the Transition Level. On "real" radar, into which the current QNH is entered, aircraft may be accepted as being at their cleared level when the height readout is within 200 ft of that level. The Manual of ATC states:

<<a) An aircraft may be considered to be at an assigned level provided that the Mode C readout indicates 200 feet or less from that level>>

So, your examples of 3907 and 3914 could legitimately be assumed by ATC as level at 4000 ft. When aircraft are climbing or descending, they may be assumed to have left a particular level when the altitude readout changes by 400ft in the expected direction..
Old 16th Apr 2008, 14:40
  #71 (permalink)  
Join Date: Mar 2007
Location: In my head
Posts: 694
Likes: 0
Received 0 Likes on 0 Posts
QNH corrected?
Yeah I wondered that, but I'd have thought that it would be corrected because Webtrak was created mostly for the antinoise lobby to check what they think they saw/heard, and it wouldn't surely be a good idea to give them more excuses than they really need for complaining?

I won't bother the ATC folks in their den ... they'll soon spot it here where it always was and they'll soon comment again if they feel the need

Edit: Aha! Told you ... Mr HD beat me to it ... they are sharp those guys, especially some of the oldies Cheers HD.
slip and turn is offline  
Old 16th Apr 2008, 16:02
  #72 (permalink)  
Posts: n/a
QNH corrected?
At the risk of getting dragged back into this resurrected debate, a quick look at the Webtrak site will tell you that that the level data is, in fact, referenced to 'the primary airfield elevation' which I would assume means Heathrow QFE in this case. The aerodrome elevation is 83ft. So, the tracks for the aircraft that concerned s and t so much were flying at altitudes of 3907 + 83ft and 3914 + 83 ft respectively - that is to say at ALT 3990ft and ALT 3997ft. Given that the pressure could change by up to 1 hPa/mB without the QFE being updated, the altitudes could be up to 27ft in 'error'. I'd say that was pretty accurate if the aircraft were assigned ALT 4000ft (which seems to be the assumption).

s and t, how much more accurately do you want the aircraft flown and controlled?

Can't we just drop it now?
Old 16th Apr 2008, 16:26
  #73 (permalink)  
Join Date: Oct 2004
Location: UK
Age: 51
Posts: 171
Likes: 0
Received 0 Likes on 0 Posts
Spitoon is closest.

Worse case, Webtrak can be 127ft out.
Flightman is offline  
Old 16th Apr 2008, 17:38
  #74 (permalink)  
Join Date: Mar 2007
Location: In my head
Posts: 694
Likes: 0
Received 0 Likes on 0 Posts
Drop it if you wish - but the only time I ever had to heed directions in the same bit of sky in a VFR single crossing the zone I was generally given "Not above 2400" and we were taught better make darn sure it was not above 2300' in practice. So then you get LCY traffic ground up to 3000' and LHR vectoring traffic at exactly 4000' it just doesn't leave much margin for error - and with all that climbing and descending going on having one stooging around right on the limit for several minutes including an orbit, and causing another aircraft to orbit right there also (which is what happened I think when it finally got fitted in), it all just looks a bit too concentrated for general consumption.

But as always I am open to all criticism ...
slip and turn is offline  
Old 17th Apr 2008, 01:54
  #75 (permalink)  
Join Date: Jun 2001
Location: britain
Posts: 679
Received 7 Likes on 7 Posts
Report now on UK Airprox Board website.

bean is online now  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.