Mid-Air Collision over Southern Germany (merged)

[OVERTALK]

Whippersnapper

RE: "154's apparent failure to respond to radio or TCAS. "

The UNCTUOUS Post on Page 10 (of this thread) addresses this point quite effectively.

The CHIRP about the Radio Management Panel (RMP) explains it all to me - and quite satisfactorily (and the CVR might amplify this). The Russian pilots possibly got a call from the galley about "what meals they each wanted" (and of course because captain and copilot have to eat different meals, they would have both been on intercom (and off the ATC VHF monitors automatically, courtesy of the glitch in most aircraft's RMP setup - as described in the CHIRP).

The key to the accident is the missed first and second calls and their response to the urgent third ATC call (but by that time the 757 was in urgent TCAS RA avoidance action and the Russian pilots simply followed ATC instructions, negating the 757 TCAS's RA solution). I would suggest that as it would now appear that the Tu-154 is TCAS equipped, it was that cooking off of the initial TA over the cockpit speakers (and in any headsets they had on) that alerted the Russian pilots - and they then went for the radio Tx/Rx buttons because a 90 degree crossing angle is absolutely the worst for visual acquisition, particularly at night, and they couldn't see the conflicting a/c.

Once they'd re-selected their VHF radios they caught that third urgent ATC instruction. AND THEN, not realising that it was the THIRD (not having heard the first two), they quite reasonably followed the ATC urgent instruction to descend (which by that time was so stale as to be useless). A major glitch with TCAS is that, as in this case, you can have ATC and TCAS working in ignorance of each other (and fatally, against each other). As a last minute J.I.T. (just in time) system it leaves much to be desired. There is also a major glitch between TCAS II variant 7 and earlier TCAS II's (that may well have played a part). The TCAS 2000 use of mode S to give lateral avoidance solutions would be an improvement because any turn will also provide a beautiful visible planform to the other crew (instead of a head-on dot or an oblique profile).

[Proceed As Cleared]

TomPierce,

I agree with you absolutely, on one thing:

You better do refrain from making any further comments!:mad:

The same applies to everyone in here who condemn the controllers involved.
Some of you guys behave like those stupid journalists who don't have any idea at all how ATC works.
It's quite simple: If you don't work in ATC you can't have an in depth knowledge of procedures, daily work and problems involved.

Discussing the matter: fine.
Speculating about reasons and blaming someone before the investigation even started: bollocks. That's the above mentioned journos' business.

71 people have died in an absolutely horrific accident.

2 ATCOs have experienced the utter nightmare a controller can possibly encounter. They will have to live with this for the rest of their lives, no matter if guilty or not.

And countless people believe they already have the answers as to why and how it has happened and who is to blame. Unfortunately some of them can be found in here, a forum consisting of aviation professionals.

Well, if you wanna claim to be one of them, then behave like one!

[brockenspectre]

Proceed as Cleared which is why I asked my two questions. What is vital is that the genuine truth here is identified - to have such a tragic accident occur in middle Europe, in what might be considered part of the most sophisticated ATC system in the world means that all branches of the aviation world owe it to all of the aviation world to establish the clean truth, to publish the clean truth and let us all learn from it! Whether it is cultural thinking, regional practice, system failure +/- anything else, it is vital that the clean truth is known here.

Standard Departure excellent post. Thank you!

[PaperTiger]

one aircraft from a country whose understanding of English might not be the best, flying an old airliner
Tupolev 154 built 1995
Boeing 757 built 1990

No preconceptions here, are there now ?

[NorthernSky]

We needed a reminder that air safety, especially in the ATC world, is not something to be taken lightly. We didn't need this reminder, but we have it now.

May I appeal to all colleagues involved in air transport, whether regulation, operation, airline, ATC service provider, from the lowliest tyro to the Chief Pilot, from the ATSA loading strips to the ATC service Director, to remind themselves of this next time they think about cutting a corner, launching an ill-advised initiative, or papering over a crack.

A truly terrible accident. My sympathies and condolences, and those of Mrs NorthernSky and the family, to all concerned.

There are more stars in tonight's northern sky. Let them shine brightly.

[EDDNHopper]

Oh, those wild, wild speculations! Noone has seen the CVR transcripts, the black boxes haven´t even been opened yet, most bodies still haven´t been recovered, and we get, in these posts here, everything from "urgent third call from ATC" to "meals being served, therefore the Russian crew did not respond". I am somewhat disappointed about the unprofessionalism of many of the posts in this thread.
Having said that, I must admit I am not a flying professional. But is there not a difference between "rumour" (this forum!) and mere phantasy?

:confused: EDDNHopper

[DFC]

What people in the UK should remember when they point the finger at Swiss ATC is that London controllers routenely accept aircraft from France northbound at the same level as westbound aircraft when both aircraft will cross Brookmans Park (BPK) beacon at the same time. They do this in "the anticipation" that they can change the level or vector the aircraft at a later time......Does this sound familiar?

Furthermore, the single computer that supplies data to the 4 UK atc centres and the busiest airports is switched off about once per week and when this single computer is off or as in recent cases has failed then the conflict alert system is not available to controllers.

Perhaps a UK ATC person could comment on the above.

DFC

[PAXboy]

I have read the posts in this thread from start to finish and realise that it is pointless to be another voice in the wilderness, asking people to read the thread before posting, repeated information adds nothing.

The Chief Pilot has a very fyne system here and it is being overloaded with repeated detail and whole splurges of text pulled from other sources, rather than a simple link, or a one sentance summary.

On Page 7 of this thread, Capt PPRuNe requested:
Please feel free to start a condolences thread on the Aircrew Notices forum.
I should like to echo Paper Tiger's observation about preconceptions but postulate an answer to a point raised early on. Someone asked why the media were concentrating on the Tu 154, this in the context that the blame was being shoved their way.

In all the photographs, still and video, the single largest piece of a/c was the tail section of the Tupolev. Given that the impact was at FL353 (or therabouts) it is worth noting that the tail section with vertical stab and top fins was almost in one piece and engine pods were nearby. It is said that Tupolevs are still built on the Heavy Metal scale!

Seriously, that was what the journos could see, the Boeing seems to be in smaller bits and so attracted less attention from the camera folks. Also, the tailfin had the company emblem on it, something that editors would say adds greatly to the picture, as it is something that people can understand more than just twisted metal. It is also poignant.

[ferris]

Can everyone stop 'blaming' and apportioning 'responsiblity'. You really are making me sick. It's bad enough that this happened, but to be launching in with fatuous crap about blame........????
Fine, discuss possible 'scenarios', offer 'opinions' etc. Without the facts you are just talking crap. How does anyone yet KNOW that the Russians had received a climb RA? Never heard of TCAS giving conflicting RA's? If the DHL crew had received a TA, where was their situational awareness- not asking for the traffic/ aware the traffic was not responding to descent instruction/knowing the traffic was instructed to descend but blindly following RA to disaster? You can blame the cleaner if you try.
The discussion about TCAS is very important. I have come to realise that it is a double-edged sword: you guys out there relying on it are headed for a fall. And I am not just talking about mis-identifying traffic, either.

[nosefirsteverytime]

Sorry to put this up here, but as there are about 19-odd pages of replies to this thread, there are only three replies to the condolences thread on Misc! :mad:

I think condolence messages are more important than theories and finger-pointing, and I'm sure many of you agree..........

http://www.pprune.org/forums/showthread.php?s=&threadid=58388

[Alpha Leader]

Swiss ATC remains the focus of criticism following the mid-air disaster in Southern Germany. On Wednesday, Skyguide had yet again to correct its own earlier statements. A recent report by the Swiss BFU (Air Accident Investigation Bureau) has also pointed to deficiencies in Skyguide’s radar systems.

According to Skyguide’s latest statement, there is no doubt that their conflict warning system at Zurich Kloten was out of service on the night of the mid-air collision. Anton Maag, the manager of the Air Control Centre, confirmed this on late Tuesday night on Swiss TV. Software modifications were being carried out at the time which necessitated that the system be turned off. But Skyguide spokesman Patrick Herr insists that it is a purely hypothetical question whether this system – if it had been switched on – could have prevented the disaster.

Skyguide has served up confusing information concerning the movements of the second controller on duty that night, and who had been on a break at the time of the mid-air collision. Maag had said on Swiss radio that by taking this break, the second controller had breached internal rules. A few hours later, this statement was rejected by Philipp Seiler, Skyguide’s operations expert. He said that the cited internal rules requiring two controllers to be on duty at all times only applied to day time operations; at night, such breaks may be taken by arrangement between the two duty controllers even if the conflict warning system is inactive.

Skyguide rejected accusations that it was providing information piecemeal and insists it is only releasing continuous updates as new insights become available. “It is absolutely not our intention to apportion blame or to try and absolve ourselves of our responsibilities” said Herr.

Separately, arecent report by the Swiss Air Accident Investigation Bureau (BFU) has raised further questions about Skyguide’s reliability with regard to its radar systems. The report, released on 26 June, points to deficiencies – and in one particular case the BFU experts categorize the problem as “serious” – in comparison with standards at Eurocontrol; the paper contains a number of specific recommendations to raise safety standards. Skyguide’s Philipp Seiler refused to comment on the individual points raised by the report, citing these were technically very complex issues, but he stated that Skyguide would investigate all problems mentioned.


The above based on AP

[foxmoth]

Those that are condemming the speculation need to remember we are not just concerned about THIS incident, but about possible future incidents as well, many of us have seen areas where the system is not perfect (eg since sept11 having to do all coms through the cabin call system) and some of these are being raised as much to avoid this in the future as to suggest a possible cause for the Germany crash.:(

[VisualFlightRules]

I have followed vanman's link to the chart (as posted by Skyguide) regarding the a/c tracks before the collision. As depicted, the DHL a/c was heading on an "eastbound" course. So, am I missing something here? According to RVSM, it should have been cruising at an odd FL at first place, should'n it? Not trying to blame anybody...just trying to understand the situation (neither a pilot, nor an ATCO) .

Regards and my sincere condolencies :(

[3forty]

What puzzles me is the "coordination" of Eurocontrol.How come this two flights ,in a converging route,were not separated long before they entered swiss airspace ? I´m not sure the lone swiss controller is the only culprit,although it seems he still had enough time to correct a dangerous "handover".But the question remains:
Are the different sectors of air traffic control talking to each other?
Can we trust this system or should we go back to "blind" transmissions to protect ourselves and our pax ?

[Alpha Leader]

Investigating near misses in 1998 and 2000, Switzerland's Air Accident Investigation Bureau (BFU) has released a report with a number of findings that in light of this week's mid-air collision are worth considering,

The paper, titled “Final Report on Skyguide Radar Systems” was released on 26 June 2002. Its main finding is the underlying inaccuracy of the radar system used by Skyguide. Radar data acquired in Zurich and Geneva respectively contains significant discrepancies to the extent that serious questions have to be raised about its integrity.

The data did also not conform to Eurocontrol standards which require all radar data to be time-stamped with UTC.

The problem areas uncovered by the report were considered particularly serious in their impact on interaction with ATC systems in neighbouring countries and on military ATC (Switzerland’s Skyguide is unique in Europe as it handles both civilian and military ATC). Even just a few seconds of discrepancy in timing during handovers would be sufficient to falsify the position of a/c by 500 meters or more.

The findings of BFU’s investigation of the near misses of 14 January 2000 and 24 August 2000 also highlight that the flight paths of aircraft may either not show up on a controller’s screen or that aircraft previously shown on a screen can vanish. The BFU report thus recommends augmenting the ATC secondary radar system with primary radar system capable of providing total and around-the-clock coverage of the entire air space. The Swiss government commissioned a study into this on 26 June 2002 (i.e. on the day the report was released).

Finally, a third problem area was identified in that the legal recordings did not concur with the flight paths and data shown on controllers’ screens. This means that the reliability of Skyguide’s recorded data used for accident investigation purposes is inherently compromised. The report urges to upgrade Skyguide’s legal recording capability to Eurocontrol standards, so that any event may be reconstructed at controller level. In particular, data reconstruction must be made available for the display of aircraft position, screen display settings and all control panel settings.

[Capt Pit Bull]

Boulderman

'Climb' and 'Increase Climb' RAs are inhibited based on altitude / config parameters. These inhibitions are gross only, the crew must protect the flight envelope. E.G. lets say you've got some ice on the airframe. TCAS can't account for that, so you might get an unachievable climb.

Crews should be trained to do the best they can. E.G. manoeuvre in the correct sense as much as possible. Even doing nothing (say engine fails as you go to pull up) is safer than thinking 'can't climb! I'll have to dive under him....'.

Incidentally, at low rad alts, 'descend' and 'increase descent' RAs get ihibited as well.


Sponix,

Granted the media are saying b757 descended after the t154, but thats not consistent with the RA alerting time at that altitude versus the report of the t154 leaving at 25 seconds.

The RA alerting time is at that level, if memory serves, 35 seconds, which incuding 5 seconds reaction time put the b757 out of its level just before the t154...



Findo,

No, the message is 'Never manoeuvre opposite to an RA', which is quite different to 'Never choose not to follow an RA'.


Whippersnapper

TCAS does not take precedence to GPWS.
GPWS warnings have higher priority than TCAS. TCAS Aurals are inhibited by GPWS activation.

Rationale - Most potential collision scenarios would be a horizontal near miss even without TCAS. Better to risk that than to hit terrain.


Nigel On Draft

The London Terminal Control trainers have been teaching this for several years (they were kind enough to help us out with ATC procedures for our TCAS course, so that the crew would know what was going on at the other end of the radio).

The intermittent contacts on your traffic display are caused by your TCAS going in and out of 'Interference limiting mode'. It is quite normal - only traffic in full time tracking is shown, which any threat will be. Remember, the traffic display is not really designed to give you SA, but only to get your eyes on the target in the event of a TA. Anything else is a bonus, and must be viewed with caution. If you want more info about Interference limiting mode, drop me an email.


Everyone.

On the topic of the Mk 1 eyeball, can I please draw your attention to this post I have made on Tech Log. I don't claim it is a factor in this terrible accident, but I hope people may find it of interest / use.

http://www.pprune.org/forums/showthread.php?s=&threadid=58559

CPB

[Alpha Leader]

Conflicting and evasive statements by various Skyguide executives are fuelling suspicions about the events that tragically ended in a mid-air collision over Southern Germany on Monday night.

Whilst Skyguide’s Air Control Centre manager Anton Maag had said earlier on Wednesday that the second controller on duty at the time of the disaster had taken an unauthorized break from work, this statement was retracted later in the day by Skyguide’s Operations Manager, Philipp Seiler. He contended that the break taken by the second controller did not contravene internal regulations, thus contradicting head-on his own superior’s statement made only hours earlier during a radio interview. Maag had said that the second controller should not have left his post as the in-house conflict warning system was down at the time.

According to Seiler, Maag’s initial statement was based on the wrong assumption that the internal regulations he was referring to were valid for both day and night duty, whereas at night, according to Seiler, breaks may be taken when mutually agreed between the two controllers on duty. Whilst being adamant that his version was the correct one, he refused to provide hard copies of the internal guidelines, citing this was against company policy.

Above compiled from Swiss agency reports

[14FIVE785]

VFR

An earlier post had the 757 on UN851, which is non-standard ICAO RVSM levels Eastbnd i.e. EVENs, which wud put him at a similar profile as the westbound TU154 on UL856 which is standard ICAO westbnd levels i.e. EVENs !

[Alpha Leader]

Given the amount of back-crawling Skyguide's executives have had to perform, the company's image is taking a battering at a time that could not have come worse.

Last FY: CHF16million loss on CHF275m revenue; this FY: loss of CHF15million forecast.

This could well blow out, as the current impass over a Swiss-German air agreement (which includes ATC sectors) is going to be harder to solve and no German politician can be expected to let Skyguide continue to control air space over German territory.

Skyguide has also committed to spending CHF85million to move its ACC from Zurich-Kloten to nearby Dübendorf Air Base.

[EuroATC]

I wish everyone on this forum would stop speculating and giving bad information.
for example...
UN851 does not use even levels?? All northbound routes are EVEN and southbound routes are ODD get it right guys!!
You guys talk about a dangerous handover and a need to change some sort of procedure blah blah...
well how do you know this??? are you familiar with the procedures at Zurich ACC??
Talk to someone that flies in and out of Munich and they will tell you that there is a change from ODD to EVEN/EVEN to ODD flight levels on the route
I take it most of these posts are from pilots who do not have a fundamental understanding of ATC. Why don't we all as professionals sit and wait for all the facts.

[EuroATC]

Old jet jockey quotes...

"If the system is working as designed the controller should not be faced with a traffic confliction. This should have been resolved during co-ordination prior to handover so no time should be needed. If however the co-ordination was faulty one might expect a wide awake controller to identify the conflict on initial contact."

WOW, when was the last time you worked enroute control? We are handed conflicts at least half a dozen an hour. There are 6 ACC's handing over traffic to us where I work..conflicts are inevitable...
If we had to co-ordinated level changes before handover to avoid conflicts a flight would climb and descend 1000 ft at least a dozen times during his flight...

[Standard_Departure]

Euro ATC.

I understand where you are coming from, and it is understandable that you are concerned that speculation is based on non-factual (pre-investigation) information.

The reality of the matter is as follows.

If you look at the Pprune, the name says it all, RUMOUR NETWORK. People here are speculating, they are discussing possibilities based on experiences, rumours, press releases etc….

Whilst there are some unnecessary comments, and some way out theories, generally the moderators tend to keep things in check.

What we as professional members of the aviation community can do is to shed light on the situation, either from a technical or a procedural perspective, always remembering that even we may not fully understand the specific details or human factors that may or may not affect this specific case.

If you find the concept of speculation unbearable, then you should CHOOSE not to take it seriously, or even CHOOSE not visit the web site.

With regard to this specific accident, there are some concerns that seem to catch my eye (I am an ATC)

Skyguide has made numerous press releases over the past few days that either contradict previous statements, or based on their content, appear to be pretty incriminating in one way or another.

Based on some of the information that is available, there seems to be some glaring questions with respect to the controllers' lack of action immediately after the BTC came onto the frequency. That is to say during the four minutes between initial contact (hand-off) and the first decent instruction (50s prior to impact).

There may have been no requirement based on SOP’s to coordinate an alternate level inbound for the BTC, and that I accept, what I find difficult to understand is why it took so long to initiate a decent instruction to the BTC (or any other means to establish standard separation).

[Standard_Departure]

Can anyone provide some information for me please...

1. What is the name of the (North-South) AWY that the DHL was on?

2. What is the name of the (East-West) AWY that the BTC was on?

3. What is the name of the intersection at which these aircraft collided?

4. What are the names of the respective sector entry positions that these aircraft entered the swiss sector on?

5. What are the respective distances between the sector entry positions and the intersection where they collided?

Thank you in advance

[BL]

I flew through this airspace less than an hour before the crash, blissfully unaware that the Swiss ATC was operating at anything less than full capability.

For you Controllers heres a question:

Would it be feasible to indicate on radar identification that your system is operating at less than 100% (eg conflict warning system not operating)?

This could be done by changing the phrase "radar identified" to some other term which would make pilots aware of what is happenning. Anytime the system was operating with less than full backup we as pilots would know to listen out more attentively and perhaps delay tasks which require one pilot to leave the ATC frequency.

How often does this conflict warning system get turned off?

[eyeinthesky]

The following link provides a very alarming development in UK airspace.


http://www.pprune.org/forums/showthread.php?s=&threadid=58576

[Standard_Departure]

BL,

I appreciate your concern; however there are a few things to consider;

There are many places in the world that do not have STCA or MTCD. There are also different types of conflict detection tools in use at places that are equipped. The differences between these are based in the manufactures formulas and mathematical algorithms used to to determine weather or not a conflict exist. Some are simple and others are complex. It may not be practical to have various specific types of identification based on equipment serviceability status.

You have however raised am interesting point. It may be worth having various sectors graded according to their respective conflict detection abilities and serviceability levels of that equipment (including levels of redundancy). Such grading could be agreed on and established by the appropriate authorities (ICAO, JAA, FAA, CAA etc) and published in the respective AIP’s, with downgrades due to maintenance promulgated in NOTAM format.

Regarding to the switching off of Conflict Detection Equipment.

I am not very clued up in this regard and will await a response from a more qualified source, along with you.

PS: Ice Pack, It's "Hear Hear"

[vanman]

Whilst doing a bit of research in an attempt to answer some of Standard Departure's questions above (sorry - no luck as yet) I came across this quote on the Skyguide www site. For the record it's buried in http://www.skyguide.ch/flash/anim1.htm. But it reads:-


quote:
--------------------------------------------------------------------------------
"Switzerland being a small territory, the controllers are given very little time to react. Due to high density, climbing and descending traffic air navigation services in Switzerland are complex and difficult to handle."
--------------------------------------------------------------------------------



This to me sounds like a clear admission of the problems associated with the lack of a pan European ATC structure. Clearly such a restructuring would allow sector boundaries to be constructed so as to maximise aircraft throughput and safety, rather than to (broadly) align with national boundaries.

I am aware that this latest accident occurred over German territory in Swiss controlled airspace, but clearly, by there own admission, it is still of insufficient size to allow effective ATC to take place.

Please also spare a thought for the occupants of the Crossair Bae RJ which recently crashed on hills East of ZRH whilst performing a non-precision approach to RWY 28 as they were procluded from flying the serviceable ILS onto RWY 14 at that time of the evening as it generates noise on the ground below in what is German territory.

If we wish to push more and more aircraft into the same infrastructure safely, then national boundaries have got to go...

[410]

Anyone who’d care to take a look at my posting history will see that I’m an unabashed ‘single issue’ poster, and that my as yet totally unsuccessful crusade touches closely on this tragic event.

There have been some gems among the dross of what must be one of the longest threads I’ve ever seen on Pprune.
Fox3snapshot: Additionally my fear is that amongst Aircrew and ATC alike, too much emphasis and reliance is being placed on the TCAS system… I liken TCAS to a safety catch on a loaded weapon – and how many people have blown themselves (or a colleague) away after pointing a weapon at themselves or their colleague saying those famous last words, “Don’t worry, it’s not loaded” or “Don’t worry, the safety’s on”? I’m very glad we have TCAS, but I can’t for the life of me understand the way so many of my colleagues seem to think they can totally dispense with other pre-emptive measures to avoid collision because “TCAS will save them”.
willadvise: Without preempting official investigations and if the information provided in Alpha Leader's post is correct, I would suggest that 50-90s prior to conflict time is far too late to initiate a level change.
Standard_Departure: Surely it is not normal to leave a separation instruction so late that a non-compliance immediately causes a bad situation to turn into a desperate disaster..
Don’tPanic_Don’tPanic: I also feel very uncomfortable about the ATCO waiting approx. 1 min. prior to "loss of separation" before instructing an aircraft to change level. Compounded by the fact the pilot did not immediately respond/comply. It's a sad reality that pilots do not always do what we tell them to do immediately.
vertigo: I have been involved in an incident when TCAS instructed a climb to resolve one conflict, only for a TCAS descent instruction immediately after the climb was commenced as there was further traffic descending 1000' on top. The pilot was left with little option but to take a 500' level and try his best to steer between them. That’s exactly what TCAS is designed to do when confronted by multiple ‘above and below’ conflicting traffic.
vertigo (again): I offer no speculation on this tragic accident, merely stating TCAS is not perfect and all of us should endeavour to understand its limitations. Wise words, but as I’ve stated on this site a very long time ago, the major limitation of TCAS is that it relies on both pilots doing exactly the right thing, sometimes immediately – and in some cases, (not, I stress, in this case), that immediate, correct action might be demanded of a very junior, inexperienced second officer occupying the Pilot Flying seat as cruise pilot.

The other shortcoming, as mentioned in another post, was highlighted in the BA/KAL very near miss over China some years ago – which involved two 747’s full of passengers. Trusting in TCAS, you’re trusting that some unknown technician from some unknown other company hasn’t mangled the canon plug in the other aircraft’s TCAS system so that it is providing inaccurate altitude information – as happened in that case.
vertigo (yet again): I'm sure there will be lots of lessons for all of us from this tragedy. Amen to that – and let’s hope someone in authority has the foresight – and guts – to slam the stable door before the proverbial horse has bolted on what to me is an obvious glaring potential for disaster. The extreme accuracy of GPS/IRS makes the possibility of something like this occurring again less than remote. It is no slur on the professionalism of Air Traffic Controllers for us, the line pilots, to insist that a system be put in place that does not demand instant, absolutely correct reactions from a Duty Controller should one solitary mistake be made by him one of the many pilots he deals with or the controller in a neighbouring sector. Offsetting would provide that extra buffer in many, if not most enroute conflicts – although I accept, not in this case. But do we have to wait until such a head-to-head mid-air occurs to prove it might help prevent one occurring?
Captain PPruNe: How many times, especially at night have any of us missed an initial call? Guilty as charged – as recently as last night, on a flight duty that was all of ten minutes under the maximum allowed.
shakespeare: know we have flogged this one to death before, but this possibly would not have happened had BOTH a/c been cruising at STANDARD cruising levels. Both aircraft were at the correct standard flight level – FL360 is a correct cruising level for a westerly track under RVSM.

I live in hope that there’s one journalist out there who might look beyond the ‘blame game’ so many in the media seem to be playing after this tragic incident. Maybe he or she could do some research – (much information is available on this site) - and demand a few answers from ICAO and ATC over the well-documented and (by far too few, it would seem) acknowledged problem that ultra accurate GPS/IRS navigation systems have brought up in ensuring that opposing traffic occupies exactly the same piece of sky in azimuth. Start with
http://www.pprune.org/go.php?go=/pub/tech/MidAir.html
and
http://www.pprune.org/go.php?go=/pub/tech/MidAir2.html
and then just check out my many posts on this subject on this site.

[Volume]

There will be a press conferece held at the BFU (http://www.bfu-web.de) at 13:00 UTC with the german minister of transportation and the director of the BFU speaking.

First RUMOURS indicate that a first glance at the 154 CVR is performed showing that the first radio contact was about 90 s before the crash (as skyguard initially stated), BUT this contact was the 154 asking ATC how they should avoid the traffic ahead ....

confirmation in about 1 hour (maybe)

[atc_ring]

....of the investigations, one thing should be emphasised (as it permeates from the euro_atcontrollers email group):

it will be very unfortunate (looking for a stronger word here) if a 1976 Zagreb (during Tito's heyday) type of trial is to be repeated in Switzerland.

ATCO's all over Europe are standing by their Swiss colleagues!

[EuroATC]

Some very good posts indeed...
About STCA conflict alert, this is a very new device to the ATC world and is not utlised everywhere, for example in Canada where I used to work... NO CONFLICT ALERT. Just because there is not conflict alert does not mean that a sector/ACC is running at a reduced capacity.
We talk about small sectors because Swiss territory is so small, well it's not much different here than what it was in Toronto Canada where I was before and of course in Canada we have all that immense airspace :)
There is alot of talk about a single sky in Europe avoiding this type of problem. The reality is that Switzerland is right in the middle of most crossing traffic to major Euro destinations. Just look at last summer, Geneva and Zurich were the cause of a big portion of delays throughout Europe due to staff shortages.

Standard Departure, if you want to know what it's like here, talk to your collegue in Dubai that used to be here. He knows me very well.

[Standard_Departure]

Euro ATC,

You could be talking about one of two guys, RB and JE, to which do you refer ?

..

[Alpha Leader]

According to gazeta.ru, Capt. Alexander Gross who was in command of the doomed TU-154 airliner had actually radioed Swiss ATC 90 seconds before impact to alert them to information from his own onboard TCAS, asking whether he should really follow TCAS instructions to descend (whilst the other a/c, the DHL B-757, began descending as well). Skyguide apparently confirmed instructions to descend.

Gazeta.ru cites sources within the Russian investigation unit set up for this mid-air collision.

Swiss ATC company Skyguide says it is aware of the Russian reports but does not wish to comment prior to a statement by the German BFU (Air Accident Investigation Bureau) which is planning a media briefing this afternoon GMT.

Rumours out of Germany suggest that the Skyguide controller might have been asleep.

[Low-Pass]

To follow or no to follow?, that is the question. Do you follow the instruction of TCAS or the controller when they are telling you different things? Common opinion seems to be to follow TCAS. But then questions are raised about it's reliability.

So is it possible for ATC to know what a TCAS instruction is? Please bear in mind that I'm not a controller and not an engineer so I don't know what's practical or possible from these points of view. However, it occurs to me that if a controller knew wht a TCAS message was, s/he might issue compatable instructions. If not, it might also give a pilot more faith in folloing ATC instructions should the differ from TCAS.

I'm not making comment on the cause of the crash, this just seems like an area for misunderstanding. Can it be solved?:confused:

[Standard_Departure]

Low Pass-

In a nutshell, no there is no automatic means for the ATC to know what the TCAS is telling the pilot (but that would be a usefull tool). Pilots may actually tell ATC what is happening if they have the time or the presence of mind.

My understanding is that pilots MUST follow TCAS RA's (Resolution Advisories) even if they contradict ATC instructions. It may of course not be easy if the ATC is "shouting" an instruction to climb/descend for "Traffic Avoidance".

[Konkordski]

My understanding is that TCAS takes priority unless the pilot considers that an alternative evasion manoeuvre would be less risky.

[EuroATC]

JE of course... we are both Canadian, I don't know the guy from ZH

[AEROVISION]

Alpha Leader

I just saw the press conference on tv and they showed both CVR's. They are substantially damaged and are not yet listened to.
Also a statement from swiss ATC there was nothing on their tapes indicating a TU154 warning as to the position of the 757.
BFU also not mentioned anything of the sort.
They warned for speculation in the press.
Best regards
A.V.

[Proceed As Cleared]

Facts and statements from the latest BFU press conference (14.30 UTC):

STCA was turned off at 21.00 UTC for maintenance

Required minimum lateral sep therefore increased from 5NM to 7NM

Assuming a speed of 450kts and a rate of descent of 1000 ft/min.,
time of clearance required before crossing to achieve 7NM: 90 secs

Actual time of descent clearance given before crossing: 44 secs

No reply

Time of second attempt to give clearance (after no reply from pilot) before crossing: 30 secs

Descent commenced by TU crew

Transmission on frequency 14 secs before impact:"TCAS desent".
Although not yet confirmed, it is assumed that this transmission came from the DHL crew.

Both aircraft were, according to Eurocontrol, equipped with the latest generation of TCAS systems.

Magnetic tape of flight recorders are damaged and have not yet been analysed.

There is, according to the BFU representatives investigating skyguide's role in Zurich who listened to the ATC transcripts, no transmission of the TU crew 90 secs before impact mentioning Traffic Advisory shown on TCAS.



Note: Theses are all statements made by BFU representatives.

[Capt Pit Bull]

Low Pass, Standard Departure.

There is, within the TCAS / Mode S system architecture, a downlink format for passing RA information to a ground station.

It just isn't implemented yet, AFAIK.

I have a recollection, though I couldn't swear to it, last time I looked at this side of things (about 2 1/2 years ago), this ATC downlink was being trialled at a couple of ATC unit in the USA.

CPB

[Oldjet Jockey]

DFC

I note your comment that Northbound a/c are handed over from France to the U.K. at the same level as crossing traffic at BPK.

From ABB to BPK is 15 to 17 minutes depending on cruising TAS or G/S. This is three times as long as the time available in the German/Swiss handover and involves(or at least did in my days) two UK sectors, names now changed to numbers, but used to be Lydd and Clacton, so the Lydd sector would not have information on the BPK traffic until co-ordination was commenced between the two sectors and this would be well before the traffic left the Lydd sector. Not at all the same situation as in this tragic accident.

I hope this answers you question:rolleyes:

[Oldjet Jockey]

Euro ATC

Since you ask I retired 6years ago, and have certainly controlled traffic under the conditions you describe, but that is surely in very busy periods with heavy traffic much of which is climbing or descending. This incident took place during a night duty when there were only 5 a/c on the sector (if reports are correct). I stand by my belief that in all the conditions at the time the a/c should not have been accepted at a conflicting level with only 5 minutes to crossing point. It leaves no margin for frequency change problems or the possibility as some one else has mentioned of a stuck transmitter, or for that matter any other communication difficulty. I do'nt know what the co-ordination SOPs are but merely point out that this is an area that has to be seriously examined during the investigation.

I feel very sorry for the two controllers concerned and hope that all turns out well for them, but lets not sweep the problems under the carpet in support of our colleagues. Our main sympathies should lie with the families of the victims and our hopes should be that all of the factors that led to the tragedy are thoroughly investigated without fear or favour to ensure as far as possible that ANY inadequacies in the system are swiftly dealt with. I rest my case!

[Celtic Emerald]

Talking about midair collisions I feel I must quote an experience my brother (& he's not prone to exaggeration :eek: ) had over Portugal while flying from Tenerife to London some years ago. He was in a window seat staring nonchantly out the window when much to his shock & that of other pax another plane passed so close he was able to "distinguish the faces of the pax on the other plane" yet funny it never made the headlines. I wonder how many near misses like this occur which because they never turn into a full blown tragedy/collision go unreported? :mad:

Emerald

[Algy]

excerpt from Flight International TCAS feature, 18 Jan 1995



...All TCAS 2 units have the capability to downlink RAs to Mode S ground stations and the FAA has experimented with implementation of the TCAS RA-downlink feature. Controllers could thus be notified automatically of RAs displayed in aircraft under their control.

"There might be some benefit in bringing the controller into the loop. Overall ATC system-management may be improved by letting controllers immediately see the RAs generated in the aircraft cockpit, rather than having the controller wait to be notified by a pilot after the fact," says Williamson.

Up to now, no provision has been made to transmit the RAs to ATC sites from Mode S ground stations for display.

In 1994, the FAA conducted a test at Baltimore/Washington International Airport, in which ten controllers participated in a simulation experiment designed to define the human-factors interface requirements for the displayed RA information.

Initial indications are that RA downlink is useful to controllers in some RA situations and the FAA will demonstrate the RA downlink in a six-month field evaluation at Boston's Logan International Airport, beginning late this year, says Williamson. ...





Personally I'd say be careful what you wish for. Seems reasonable to tell the guys in the cockpit in effect 'obey TCAS over ATC', but a lot harder to tell controllers in effect 'don't give an instruction if you get a message saying TCAS has it under control'.

[volare]

Oldjet Jockey,

I agree that accepting traffic at conflicting levels with only 5 minutes to the crossing point is asking for trouble, sooner or later. But having spoken with an ex-SkyGuide controller that used to work in this sector, this is the norm in their system. Literally last minute level changes some 50 to 60 seconds prior to crossing are not unheard of, so from this point of view the SkyGuide spokespersons are accurate.

Trouble is, if these flaws are rectified, capacity will decrease, and the airlines and politicians will start screaming about increased ATC delays, and the ATM providers will go belly-up financially.

It's a sad state of affairs.................

[HOVIS]

Celtic E.

I had a very similar experience as a passenger on a shuttle flight in the UK a couple of years ago.
The a/c was in a holding pattern for about 15 minutes when suddenly the engines wound up and the 180 degree turn we were in suddenly became a straight and level climb.
I looked out of the port side window and gasped in shock as a BA 747 barrelled over the top of us at about 400ft distance.
I kid you not, I could read the reg!!
As we disembarked the captain was stood by the exit grim faced. I spoke to him as I passed "TCAS works then?" He give me what can only be described as an "old fashioned" look but said nothing.
God knows why we were climbing when an a/c was above us but that's what happened.

I checked all that year to see if any mention was made of this incident, nothing.

[Standard_Departure]

Volare.

If the a 50-60 second prior to impact (or crossing) instruction is considered normal in a cruise (Area) environment, then I find that in itself to be a critically dangerous situation.

If that standard is an operational thing because of traffic, then I pity the ATC's working there. HOWEVER, waiting for 4 minutes so that they can get that close (60 seconds) and then giving the instruction, when there are no other aircraft in the vicinity ???? that has got to be considered as negligent.... there must have been something else distracting the ATC, I just cannot believe that that is the way it is....

[volare]

Standard_Departure,

Indeed, a four-minute delay at night in correcting a conflicting level appears strange to me too. Something else must have caused a distraction. I guess the enquiry will reveal the circumstances.

But during peak hours, ATCOs in this area don't have the luxury of substantial advance planning of their traffic, not even in enroute control; there are just too many aeroplanes in each sector for that to be possible. It becomes an exercise from hand to mouth............

My expatriate ex-SkyGuide controller colleague took the consequences of this and declined a renewal of his contract, fearing the worst.

I pity our colleagues who must accept such conditions. Can't be possible for them to work under such pressure until normal retirement age.

From CNN I now understand that homicide charges are being considered against the two controllers on duty. As so many others have said: "There, but for the Grace of God, go I."

[120.4]

Volare

If you are correct in saying that 60 secs is in any way considered to be okay then I say that is totally unacceptable. If it has been permitted in order to increase the sector's capacity, then doubley so.

I keep hearing politicians and ATC managers saying to the public that safety is paramount. If these are the limits in use it clearly isn't. And let's not kid ourselves that it couldn't happen in the UK. I regularly (daily) see people pointing traffic at each other on the basis that they are going to something about it before it gets critical.

"I have always done it like that and not had a problem so far" is the answer I usually get. Folly. Communications can never be guaranteed.

NOW perhaps things will change.

Point 4
:(

[Devils Advocate]

In answer to Celtic Emerald (posting on page 20) whose bruv is ‘apparently’ not prone to exaggeration …..

Now I did a flight the other week, where somewhere west of the Iberian peninsular an aircraft appeared on our TCAS 1000’ below us it ( turned out to be a transatlantic bound Iberia B747 at FL330 ) was on a 90 degree intercept heading and the ‘Line of Constant Bearing’ was indeed constant. I.e. ( and to the layman ) the risk of collision might seemingly be high – whereas this other aircraft ( whilst it might of looked close – to the layman ) was actually 1000’ below us – indeed perhaps the bigger risk was from us (the pilots) burning ourselves (from our hot Tea) as we made a frantic dash into our flight bags for our DigiCams – and it would have made a lovely photo too !!

However on landing at our destination and as the pax were leaving the aircraft one gentleman let it be known to the cabincrew that he would be writing-in to ‘complain in the strongest possible terms’ about the near-miss that we had subjected the passengers too – and having done so how we had then failed to allay their fears and feelings about this ‘AirMisss’.

So CelticE, and with the above in mind, it rather sounds to me like your brother is a bit of a DH and that he should accordingly keep his ill-informed (layman) opinions to himself.

I.e. When he’s spent £50,000 of his own money in training to be an airline pilot, and when he’s passed all the written and flying exams to allow him to hold an Airline Transport Pilots License, and when (after years of trying) he’s managed to get a job with an airline that operates jets, and when after several years he has the relevant experience (i.e. several thousand hours) at the controls of a jet airliner (coz that’s what you need to sit in the Captains seat), then - and not till then - is you bruv (or indeed any other layman / pax ) suitably qualified to comment on matters aeronautical – till then, I suggest that he ( and or any others of his ilk ) keep his/their ill-informed layman’s opinions to themselves !

[Capt Pit Bull]

Devils Advocate,

bit stong there perhaps.

I'm reminded of the pax on the Kegworth aircraft.....

CPB

[Wedge]

"then - and not till then - is you bruv (or indeed any other layman / pax ) suitably qualified to comment on matters aeronautical"

Devil's Advocate, maybe you are playing the role of your name but that is utter nonsense.

I am not an airline pilot (an ex-wannabe), but I consider myself very well informed on matters aeronautical thankyou very much.

And besides, what about ATCOs, engineers, and even cabin crew. They are all entitled to their opinions on aviation matters as indeed are those who don't work in the industry.

Sort yourself out!

And what an excellent point Captain Pit Bull. I hope I'm never flying as pax with Devil's Advocate when there is an engine failure.

"There's a passenger who thinks that you have powered down the wrong engine"

"Oh what does he know! Tell him to shut up!"

It's 'I'm a pilot so I can't be wrong' complacency like that that leads to accidents in the first place!
:mad:

[BIK_116.80]

"I paid fifty-thou for my pilot licence - so I know what's goin' on!"

No, it shows that you are not very good at shopping and that you paid too much.

[Captain Stable]

I concur. It is not good CRM to eliminate what might possibly be an excellent source of information.

Under no circumstances whatsoever can 50 secs be considered safe. Even assuming that the Tu154 had commenced descent immediately, in 50 seconds they could quite conceivably (at 800 fpm = 1 degree) have descended less than 700 feet. This does not provide legal separation.

Whatever the various causes of this awful accident, I rather suspect that many systems will require major inspection and overhaul, and some very dearly-held preconceptions torn away from people's security blankets.

[411A]

Indeed....waaaay toooo much! (should have trained in the good 'ole USA, silly boy):p

Capt'n Stable...right on the money IMHO.

[FL600]

My heartfelt condolences to the families involved. I cannot imagine what the controller must be feeling. I hope that first and foremost a CSIM support group does exist in Zurich.

This event will have far reaching consequences in the aviation industry, both political and operational. Of course many questions remain, but I am Angry but not too surprised at the stupidity of the management press releases.

My personal thought... The accident occured at FL353. It seems clear that one aircraft was under an ATC clearance and one was under computer guidance... Whether the controller had made a mistake and was taking avoiding action or whether it was a preplanned conflict resolution level change, the sad truth is that nothing would had happened if the controller had not intervened and that is what makes it that much more painful.

[Alpha Leader]

As mentioned by others in earlier postings, no confirmation of Russian claims that TU-154 crew alerted Swiss ATC.

However, point made by German BFU official Schlegel about the controller violating Swiss ATC regulations which demand that aircraft have to be redirected to other flight levels at least 1 1/2 minutes prior to reaching the projected intersecting point.

[3forty]

concerning Tcas orders,they take priority over ATC.Period.
If the two planes were to follow their respective Tcas instructions,the accident would be avoided.Of course,the controller had to do something and tried to separate the flights "manualy".It would take tons of guts and cold blood to remain quiet and let technology do its job.

[arcniz]

Well, Devil, your horns are certainly showing.

Now that you're making the big money, another 500 on some sim time at Charm School might be a career plus.

Aviation is still small enough that each player affects future opportunities for all the others - positively or negatively.

More than a few folks with the price of a ticket - including seasoned travelers - are somewhat anxious about being accidentally damaged while whooshing about at the speed of a pistol bullet.

To them, crossing a thousand feet apart may seem like inches - if they perceive it as a brush with eternity. Tragic events like this one are amplified by thousands of media channels and propogated worldwide at light speed. While marching through the press reporting cycle from the tragic event to the final analysis, the story appears in various forms at least several hundred times in view of many of your future customers.

Telling the pax to sit down and shut up resolves some near-term annoyance, but it is really bad for repeat business. A little compassion for their actual concerns goes a long way. Combined with some guidance from aviation professionals, it can motivate useful infrastructure enhancements to prevent future situations of this nature.

[boofhead]

Harking back to the possible delay in response to an ATC instruction to descend... I fly an airplane with imperial measurements, and a metric backup in a metric area. When I am instructed to climb/descend I need to look up the appropriate imperial value of the new altitude in order to set it on the altitude counter of the autopilot, before I can initiate the descent, whether using Vert Speed or VNAV. It matters not that I have a display of the metric altitude in front of me, since I am required to set the altitude counter (in feet) in order for the altitude alert to operate (another RVSM requirement).
So I would imagine the Russian pilots had an auto pilot panel marked in metres, and would have to go through a similar procedure before they could start the required descent, since they were operating in an imperial FIR.
50 seconds sounds a little too short a time to me..

[320DRIVER]

Excellent point Boofhead... we fly (occasionally) into "metric" airspace and each time we get a level change, we have to take our quick reference chart and convert the value to feet to set in our FCU. Airbus makes it a bit easier because there is an option to see the selected FCU altitude equivalent in metres on the lower ECAM system display.

[AA SLF]

Wedge and arcniz -

A just a humble pax/slf that does over 100k airmiles a year, I want to say THNAK YOU for your responses. Y'all are dead on regards how the pax might feel getting off of a particular flight. Several flights on American Airlines (AA) in the past couple of years I have had the flight deck come on the PA system to advise that we had "passing/crossing" traffic coming up and to not worry about it as BOTH flight decks we talking to each other on freq (actually thru ATC contacts).

Thus, when the event did occur all (at least as far as I could determine) of the pax were "excited" about the event in a positive manner (they got to see another a/c in flight) and nobody from the pax side seemed upset/nervous at all. Lots of comments like "did you see it" ; "did you get a picture of it", etc.

Very good PR points in mind for "my" airline and pax going home with a "story" to tell their friends about their trip on AA.

If one (1) pax stops to talk to a pilot at the exit you can be sure that there were others who felt the same way who just did not speak up!! There goes all of the "good will" in a flash.

-dAAvid

[3forty]

Boofhead,you may have a good point,but I fear the clearance to descent included something like "immedeatly" because of the collision threat.In that case,you just switch the bloody autopilot off and dive.

[vanman]

If as we're lead to believe there was only one ATCO on duty, as the other had left the building and was presumably therefore not readily available, then what cover would likely be available and for what likely period of time after this tragic event took place?

I'm haunted by this horrible image of a controller having to 'keep it together' for what must be an eternity whilst a relief colleague presents him/herself. Clearly, in such circumstances, their concentration might not be completely assured thereafter.

I'm sure it's all a lot more scientific??? ....... but then I'm not to sure about anything at the moment .... I freely admit to being one of those pilots who, whilst turning on all the lights and keeping 'em peeled at lower altitudes, fully believed that the combination of RCS and TCAS meant that we had never been safer at FL360. Certainly sharpen my look in the cruise now.

BTB, When I last did TCAS sim training I was being asked to generate a vertical deflection of about 3 or 4 hundred feet to successfully 'resolve' a TCAS RA. We were given demos of the likely outcome of exceeding this, ie a further conflict at the next level.

Would a 700' descent for an RA be considered excessive? My first thought is that it is..... but then I don't fly 757s.

Lastly, after reading (days ago now) earlier portions of this never ending thread, I am a bit unclear as to whether and if so how long before the impact, a reversed RA would have been received in the two flight decks?

Thanks in anticipation of any clarification (where appropriate ;) )

PS: Devil's - I agree. Ignore, or worse, insult the punters at your peril. CPB's point is of course, absolutely correct, but also remember that the pax you p1ssed off last week is the one in the aircraft at the other end of next weeks RA!

[Alpha Leader]

German BFU (Air Accident Investigation Bureau) provides first official summary of events leading to Monday night’s mid-air collision:

Skyguide controller appears to have been at task saturation point. Between the handover of the TU-154 from Munich Control to Zurich Control at 23.30.11 and the time of the collision at 23.35.33, the Zurich controller was responsible for four flights on one frequency and another flight on a second frequency. He was responsible for coordinating flights on two separate screens. One of the flights was on approach to Friedrichshafen airport.

All this was taking place as Skyguide was carrying out software maintenance to its radar systems, for which reason these were in fall-back mode and had been so since 2300. Given this scenario, increased separation of 7nm horizontal and 1000ft vertical was prescribed.

Both the B-757 and the TU-154 were progressing at a normal speed of 450 knots. The descent initiated by the TU-154 pilot (1000 ft/min) was also routine. However, this descent should have been initiated by ATC 90 seconds prior to the projected intersection point, whereas it is now evident that the duty controller released such instructions only 44 seconds prior to the eventual collision. The situation was further exacerbated by the fact that the TU-154 crew only reacted to ATC instructions when they were repeated to them 30 seconds before collision point.

Immediately prior to the collision just below FL360 the TCAS on one of the two planes involved released dive instructions which were monitored by ATC. There is no confirmation yet as to which a/c this emanated from, but it is currently considered likely that it was the TCAS on the B-757, as it had already initiated its descent.

Investigators confirmed again that the TU-154 was equipped with TCAS, but there are questions as to whether this was operative at the time.

With both FDR and CVR retrieved, it is now evident that the tapes are in very bad condition, being both torn and deformed. It is likely that some data will be unretrievable.

Russian media reports referring to an alleged warning by Capt. Alexander Gross radioed to Zurich control about the looming collision have not been confirmed by the German investigators.

[Wiley]

It’s time to introduce offset tracking

I have to agree with 410 (page 19) – although offset tracking would not have prevented this particular tragedy, the fact that the accident did occur in a so-called ‘First World’ RNP5 radar ATC environment clearly illustrates his point: - even in the best high tech, safety-redundant environment, the ‘error chain’ can still go unbroken right up to and, it would seem, including the last vital link, TCAS.

It’s time we all started insisting something be done about a potential problem many of us acknowledge is an accident waiting to happen - the decrease in flight safety that highly accurate GPS navigation systems have brought into the equation.

Danny, this site, your creation, has come a very long way since 1996. Can I suggest that you, with the undoubted clout you now have through this site, start a loud campaign to really hammer home the concerns I think you share with 410 and many others, including me. It’s time offset tracking was introduced, RIGHT NOW, without further delay, even in RNP5 airspace, before another accident occurs with possibly far greater loss of life.

I agree that it should be embedded, but I know that will take years to implement, so let’s make it mandatory that everyone with an FMS employs it manually above 10,000’ until the embedded offset is introduced. Bureaucracy being what it is, it’s simply not going to happen unless we insist on it – or another 800 people die in circumstances that this simple fix would so easily avoid.

It’s been said before, but it’s worth repeating yet again. Imagine the meal the lawyers are going to make of it if we ever do have a head-to-head midair (like Delhi and like the one off the west African coast) when it comes out that the many calls for offset tracking have been ignored by the authorities for years. They’ll be suing everyone right down to the assistant cleaner at ICAO HQ.

[Standard_Departure]

As an ATC I feel a little bit stunned by the report issued by BFU.

He was responsible for coordinating flights on two separate screens. One of the flights was on approach to Friedrichshafen airport.

Even though they (BFU) mentioned task saturation earlier in the statement, this should not be confused with traffic numbers, there were only five.

The important part of that statement is the fact that he was working 2 different "screens". Now if that means what I think it does, then this controller was sliding from one position to another, and doing what would normally require two controllers working two radar displays, two frequencies and two of whatever else there was at each workstation.

The implication that he was working two frequencies, and was;

Firstly - running the risk of having different aircraft transmit on different frequencies simultaneously and have one or the other get lost in the ether,

or Secondly, issue an instruction to one aircraft at one position, and start "sliding" over to the other position to monitor a manoeuvre, possibly without hanging around long enough to ensure that the previous instruction was either read-back or complied to, this is shocking.

And Skyguide, please don't tell me that this is also within your tolerance limits or acceptable standard operating procedures !!!!!

The rest of the report is insignificant to me, because, for what I can see, the bulk of the damage was done when they removed TWO vital safety nets, #1 the other controller & #2, the conflict detection equipment.

I am sorry if I sound a little upset, I am.

PS: As a sidethought, was the aircraft arriving at Friedrichshafen Airport being provided with any sort of Controlled Service, in other words being vectored to an ILS or something like that, and if so, was the ATC both Approach rated and Area rated ?

[Alpha Leader]

Standard_Departure:

Re your sidethought: 'Yes' to your question about Controlled Service - 'don't know' about the controller's rating(s).

[Standard_Departure]

Hi there,

There has been some discussion now regarding the "apparent" lack of compliance to TCAS RA by the pilot of the T154.

My question is;

After following ATC instructions for up to 20 years, turning when they say turn, climbing when they say climb, adjusting your speed when they instruct you to do so .... is it not going to be extremely difficult to comply to a TCAS RA when you have an ATC instructing you (possibly including the words "FOR TRAFFIC AVOIDANCE" or "IMMEDIATELY, TRAFFIC, TRAFFIC") to do the exactly opposite of what the TCAS is saying?

I know the book (reg’s) say that except for GPWS, TCAS RA's take precedence over all other instructions, but what I am asking about is the practicality of that compliance under certain circumstances....

Thank you in advance

[Devils Advocate]

The point I was 'trying to make' ( though obviously not very well - i.e. I'll admit that in my previous post I used the term 'pax' too loosely, in as much that there are indeed occasionally people in the cabin with experience which is pertinent and we're all the better for them being there too ) is that just because some 'laymen' ( n: A person without professional or specialised knowledge in a particular subject ) perceives that it's unsafe doesn't mean that it is; Though, conceptually, whizzing about at the speed of a bullet, several miles above the Earth, in a pressurised aluminium tube, is seemingly a ridiculously dangerous way to travel.

Nb. W.r.t. to the psychology and flying, I was once told that aircraft manufacturers try very hard to make the pax forget the above by hiding all the control cables, etc., from view behind nice plastic panelling, i.e. sanitising the raw machine, whereas submarine manufacturers try their hardest to remind submariners at every moment that they're operating in a dangerous environment by leaving all the pipe work on view - interesting huh ?

That said, just because somebody in the cabin sees another aircraft in the sky, and that to them it might seem close, does not mean from the professional / aeronautical view point that it is.
Also if we were to broadcast a PA to the cabin every time we passed another aircraft it'd actually (imho) become bloomin' irritating, e.g "yep folks, out on the left there's another one heading our way"..... a short while later ..... "and there's another one, looks close but no need to worry"..... ditto ..... "and here comes another one" - gimme a break ! - and what if you then pass one close-by but didn't say anything (eating your dinner, or whatever) you'll almost certainly then have Johnny pax saying "Uhm, guess they didn't see that one coming, just what are they doing up there, it looked real close to me, I'm gonna write in and complain that they obviously aren't paying attention !".
Indeed, sometimes you're so busy in the flight deck ( reading the paper, doing the crossword ? ) that other aircraft just whoosh by and your none the wiser, and also some TCAS systems only go out to 5Nm so by the time you locate your target, in time to make a nice PA, it's gone past - but there's bound to be some eagle-eyed pax in the back who sees it and believes you were dead-on a collision course, and that it was only 'luck' that kept you both apart - despite the fact that ATC didn't feel the need to say anything to you about another aircraft and that the TCAS didn't even squeak.

As per my previous addition, it typically takes years to become an airline pilot, and we then similarly spend years in the air plying our trade, so it just seems a bit temeritous(?) to have somebody who maybe only flies a few times a year ( possibly doing less airmiles and flights than we do in a busy summer week ) suggest that you risked their lives by flying 'too close' to another aircraft and that they're going to write to your company to complain about you - err, run that by me again ?! :rolleyes:

Now w.r.t. Kegworth, yes the pax might have noticed that the left ( or was it the right, or number 1 or number 2 ? ) engine was chucking out flames / sparks, but the bigger problem ( as we all know - if you've done the CRM courses ) was the mix of experience levels on the flight deck, their characters, and how they handled their emergency.
That said, it did not help that ' They were not informed of the flames which had emanated from the No.1 engine and which had been observed by many on board, including 3 cabin attendants in the aft cabin.' (http://www.aaib.dft.gov.uk/formal/gobme/gobmerep.htm)
Veritably you or I could have been sitting in that cabin, looking out at the left donk, and it'd have made very little difference to the outcome ( which in part is why CRM's now so popular & required ).

W.r.t. flight training costs, if ones adds up the cost of the flying training and combines that with the loss of earnings during the for one year, study period (http://www.oxfordaviation.net/oxford/fulltime/key_features.htm) (i.e. you'll need money to live on) then I'll stand by the cost of £50k - and fyi I've got both UK & USA professional pilot licenses, and yes it is a lot cheaper in the USA, though it does also seem to be getting cheaper to get a license in Europe too.

[stator vane]

all this puts new meaning into those often mistakes in frequency changes that have happened to me so many times and i hear happen to others as well.

just a few seconds trying to talk to ATC on a wrong frequency suddenly has more meaning to me now.

at times the wrong frequency is given, often the freq is mis-heard, sometimes mis-dailed, or the radio not switched over to new frequency.

let's all be more careful out there.

it could have happened to anyone.

[Seriph]

What's this hangup with offset routings Wiley. Who follows the routes anyway? As in the States direct routings are becoming the norm, the 'traditional' airways system's days are doubtless numbered. In any case how many Russian and other third world outfits have sat nav. Ever been on the flight deck of a 154? Out of the dark ages.

[Oldjet Jockey]

Volare and Standard-departure

Good posts, if the SOPs are based on the bean counters considerations and ignore the basic safety considerations then it is the bean counters and those responsible for the co-ordination SOPs that put the controllers in an impossible situation, and it is these people rather than the controllers who should face the music.

I make no comment about the absence of one of the controllers and the extent to which this added to the problem as I dont know the facts. To me this was an accident waiting to happen and unless the co-ordination procedures are urgently reassessd there will be more accidents in the future.

[Seriph]

As mentioned earlier and perhaps most pertinent here is the number of frequency changes required to transit this area of Europe. 50 seconds is nothing copmpare to the delays and 'blank spots' inherent in these procedures, I guess though that any attempt to streamline the system will meet with industrial action as we have recenrly seen.

[Seriph]

P.S wondered how long it would be before the 'beancounters' would be held responsible. What in the hell have they got to do with SOP's ???

[Standard_Departure]

To Devils Advocate: Hear Hear !!

To Seriph: The reference to Off-set routings refers not to taking a traingular route to a destination, but rather to a 1/2 nautical mile left or right offset to an established airway or even direct routing between two positions.

The reason for this is (and I have first-hand jump seat experience) that navigational systems are now so accurate, that two aircraft routing in opposite directions between the same two positions actually (often) cross EXACTLY (as in wingtips virtually aligned) over and under each other. BY off-setting from the direct track or airway by 1/2 a nautical mile, both left or both right, there will be a natural 1 nautical mile separation between aircraft on opposite direction routings. This would provide a lateral (horizonatal) safety if the vertical seperation were compromised. (This would not have helped in the swiss incident however)

To Seriph: (again) The beancounters may not write the SOP's, but their decisions regarding the procurement of equipment (safety and otherwise), (dis)approving operational requests for additional staff, etc.. can often (and do often) limit the options available to operational managements scope when it comes to making SOP's.

Beancounters often go for financially viable options, operators making the same call would go for the operationally safer options.

[Devils Advocate]

Gotta say that I've never felt too confident about the 'handovers' from Padua(?) into Swiss controlled airspace and vice-versa ( e.g. when operating in / out of Milan ) it just seems that sometimes, even if only for a short minute ( usually whilst trying to get a word in edgeways ! ) you're kind of 'on your own', i.e seemingly not talking to anybody and / or not under positive control by ATC - it 's probably just a (wrong) perception but it might sometimes seem that the coordination between the Italian and Swiss ATC units is not quite as slick as one might hope for - and it's busy bit of airspace too.

Uhm, like I say, I'm not sure if the above's true, but it's just a feeling I sometimes get about it - anybody else know what I mean ? :confused:

[Konkordski]

At the end of the day Switzerland is probably too small to justify having its own ATC service, especially smack in the middle of the European core area.

They're already having to cobble together a civil/military mix 'n' match system because the Air Force and airlines are having trouble sharing out the sky between them.

Isn't it about time the airspace was carved up between the surrounding nations? Sorry, Switzerland, no offence.

[foxmoth]

3fourty and someone else made points about the Russian not following TCAS, my understanding is we don't yet know if his TCAS operated, so how can we say that if they had both followed TCAS the accident would not have happened? When the tapes are sorted we will hopefully THEN be able to comment on this, at the momment there are just too many possibles:- both TCAS's went off correctly but the Russian followed ATC, the 757s called wrong, the Russian's did not work, the 757 called down then reversed/did not reverse/called for increased descent etc. etc.

Another point has been made about frequency changes, since the extra digit was added this has certainly got worse, maybe if we dropped the 1 off the front it would mean less to retain in your head while reading it back so better retention, ALL vhf frequencies start with 1 so it is not really needed - ie 132.475 becomes 32.475 etc.

[Standard_Departure]

Hi Foxmoth,

I appreciate and respect the TCAS debate.

The way I see it, when the sequence of events reached the point that TCAS reactions were required, the system had already failed. Reacting to RA's is tant-amount (?) to clutching at straws.

[Martin A]

Just a quickie, Real issue is the the interaction of ATC instructions and TCAS, time is so tight when the TCAS goes off, there is no time for debate about which you do and if the decison is the wrong one !!! TCAS is not infallible, close calls induced by TCAS limitations, mode C encoding have happened before. As with all automated systems with only limited logic and no reasoning, most times it does a good job, but once in a while you discover the weak points.As to ATC, the debate over Swiss size is irrelevant, the average ATc sector size is not constrained by ploitical or geographical boundaries, merely workload considerations,which will of course be determined by goegraphical aspects, e.g LGW LHR interaction. No amount of open skies will change that.
As to offsets, as has been said, with direct routes, offset where ? As to the Russian aircraft's reaction, , we can only wait and see. We all know that a lot of what is speculated is just that. Probably the best thing we can do as a group is keep reporting what happens to us, TCAS RAs etc so as to get a handle on what really happens. Without hard evidence of problems in any area, we will get nothing done no matter how much we write here, so if you have issues, MOR, company reports, BALPA or whoever your union or professional association is.
A sad event which like others before it will cause some to say"ther but for the grace of God go I" or similar words
Regards
MArtin A

[vanman]

Martin A,

1) If Swiss size is irrelevant then why does the Skyguide web site state the opposite? (Pls see my previous post on this thread)

2) I agree about conflicting instructions when normal seperation has broken down. If controllers limited there input to lateral avoidance advice, allowing TCAS to control the vertical, then no conflicting instructions would be received in either aircraft (also mentioned in previous post). Maybe some ATCO will tell me the down side of this - but as yet I can't see the problem.

[Cpt. Timbo]

Here some facts from the BFU, you can also check http://www.bfu-web.de/aktuinfo-e28.htm



2002-07-05 11:00 MESZ
08:00 UTC

Findings of the Air Traffic Service Group for investigation of the accident on July 01st. 2002 with the aircraft Boeing 757 and Tupolev 154

As of: July 04th, 2002 at 14:00 LT

In the accident night, from 23:00 L the configuration of the radar data processing of Skyguide was modified. Thus the system was operating in FALLBACK modus. This requires among other facts, that radar separation values were increased from 5 NM to 7 NM.

The STCA (short term conflict alert) was not available at that time. In other words, the warning system, that indicates dangerous approaches of two aircrafts in same altitudes optically and acoustically to the air traffic controller, was not available.

At the time of the accident only one controller was responsible for the entire traffic in the Zurich airspace. He was monitoring two frequencies and two radar scopes. On one frequency (119,925 MHz) he was guiding one traffic for an approach into FDH and on the other frequency (128,050 MHz) he had to control both accident aircrafts.

A second controller was outside of the control room taking a rest.

During the work on the radar system there was also some working on the telephone net of Skyguide. Therefore the main telephone line war switched off. For the radar controllers work a backup (bypass) line was available. When trying to establish contact for coordination with FDH technical problems occurred. Between 23:25:43 and 23:33:11 LT the controller tried serveral times to establish contact with FDH. He was not successful.

At 23:34:49, 44sec prior collision, the radar controller issued the first descent clearance to BTC2937 to FL350. As the crew did not react to this clearance he repeated the clearance 14sec later. Now the crew of the TU-154 confirmed the clearance and initiated the descent.

At about the same time the crew of flight DHX611 started a descent as well. This happened without instruction from the radar controller. At the same time there was a statement on the radio that a TCAS descent was initiated. This transmission most probably came from DHX611.

From 23:30:11 until the collision at 23:35:33 the controller was responsible for 4 aircrafts on 128,050 MHz and 1 aircraft on 119.925 MHz. At 23:35:31, 2sec prior impact, another aircraft checked in.

[STCA]

SKYGUIDE WILL FRY FOR THIS !!!

The system has failed the controller, the airlines and the flying pax.

How can they possibly be allowed to manage an ATC system if they are so blatently negligent.

To the ATC(s) involved: Keep the faith man !!

[garp]

Fully agree with Martin. Talking heads on TV and radio are complaining about the amount of frequency changes due to the many different control centres where this is completely irrelevant. Sectors are sometimes so small because the traffic just wouldn't permit to make them bigger or do they expect that having one large sector with 80 a/c on the frequency will make things safer??? Take the example of the belgian airspace which can be compared to the swiss airspace both in size and complexity. Almost 2.000 flights a day (above FL245) with 6 sectors (again only above FL245) with delegated areas well into the french and german airspace and military areas all over the place. Let's put all of that on one frequency. Blaming the different computersystems operated by the different ATC units is also ridiculous. They're different but the transmission of flightdata hasn't been a problem since many years.
I am behind the radar since the mid-eighties but now is the first time that I'm thinking about my job when I'm at home. The idea that something like this could have happened to me or any other colleague is devastating. I really hope that all of the guys who were on duty at Zurich will get proper psychological help.

[LUM]

Garp, are you really an ATC controller?
The upper airspace over Belgium is controlled by Maastricht, 1 single control extending well beyond the belgian borders.
The lower airspace is controlled by Belgocontrol and is devided in several sectors.:(

[Ruslan]

Foxmoth,
If TCAS was not working or properly functioning on RA65816, then I believe no RA conclusion on board of 757 occurred considering the way TCAS II works. It could only receive traffic warning in that case, in other hands considering you’re listening comm. frequency you won’t be dive beeing aware there is another instructed for immediate descend. We should wait for tapes, fully agree here, but it really looks like Russian pilot has failed to follow RA command and commenced ATC instruction.

[garp]

Lum,
I just to took the belgian example to illustrate that fewer control centres wouldn't mean less sectors and thus less frequency changes.
Garp

[sky9]

What this accident is showing is that they are very rarely caused by a single fact but rather than a number of factors coming together.
As a pilot I am horrified that a controller is working two different types of airspace, overflights and approaches into FDH at the same time. When Conflict Alert was turned off it is nonsense to suggest that increased separation is the answer. The answer must surely be an extra pair of eyes and brains.
With regard to late ATC calls to take avoiding action it must surely be better either to say nothing and allow TCAS to work or restrict instructions to heading changes.

[ferris]

No, turning aircraft wouldn't suffice.
I'm sorry, I couldn't sit there and pray that TCAS was doing it's thing. As I have previously stated, experience has led me to have no faith whatsoever in TCAS. I would be talking a hundred to the dozen giving traffic, avoidance instructions which would include both level changes and turns, and standing on my head if I thought it would help. The fastest way to avoid a conflict is with a level change. At those altitudes, turns are fairly slow.
In most cases, I would hope that level change instructions had been issued before an RA occurs (as was the case here).
Also, importantly, I don't know you have an RA unless you tell me.

[lukewarmskywa*ker]

Hey Lum....

airspace over Belgium is controlled by Maastricht, 1 single control

What?
It may be one single control center. Even one single control sector suite. One sector it most certainly is not! The Brussels sectors at Maastricht, as Garp said, are all relatively small by necessity because of the complexity and sheer volume of traffic.

If you can think of a solution in this area, please notify Eurocontrol immediately. You'll be an instant star.

[Standard_Departure]

Ferris,

I am afraid that you don't (should not) have a choice, once an aircraft declares that it is following a TCAS RA, it is advised that you DO NOT give any contra instructions.

I suggest (as you said) that you give Essential Traffic Information (but) to the other (conflicting) aircraft.

An important thing to remember, is that as ATC's, we get a reduced re-fresh rate (sweep update) on the SSR, that is to say relative to the aircraft equipment, and it may well transpire that what you and I see on the Mode C readout is out of date by 5 seconds, and could imply that aircraft have already crossed levels and cleared each other.

Zagreb is a classic example of 2 aircraft that had actually cleared each other, but due to the ATC instruction, the climbing aircraft actually descended back into the collision path - A tragedy that you and I would rather avoid I am sure.

As difficult as it may sound, if the situation has reached the point that aircraft are saying "GFA231 IS TCAS DECENT !!" The best we can do is close our eyes and say a silent prayer.

Cya

[Alpha Leader]

From AP today at 13:32 CET:

Not only was maintenance work being carried out on the software of the Skyguide radar systems at Zurich ACC, but also on their telephone system. This latest insight comes from the German BFU (Air Accident Investigation Bureau).

The duty controller was thus working two radar screens and two radio frequencies on the night of the mid-air collision. On one frequency, he was handling an ILS approach to Friedrichshafen airport, on the other he was coordinating the two doomed aircraft.

Between 23.25.43 and 23.33.11 the duty controller tried in vain to contact Friedrichshafen airport by phone. Immediately after this (at 23.34.49, and 44 seconds before the mid-air collision) he radioed his first set of instructions to the TU-154 crew to descend.

[foxmoth]

Ruslan
I think you will find that if the Russian TCAS was not working the 757 would STILL get a TCAS RA provided the transponder was OK on both a/c, what would NOT happen is the aircraft co-ordinating with each others TCAS so that they did not BOTH call a descent, but as I said, at the momment we only know that there was ONE (757?) TCAS warning, ANYTHING else is pure conjecture (don't mind the what ifs, but some people have been STATING, if they had done this they would not have collided, far to definate a statement at this stage).

[GlueBall]

When responding to a TCAS Resolution Advisory such as "descend, crossing traffic..." it is well to do not only to descend, but also to initiate an immediate steep turn away from the target highlighted on the TCAS screen. It's the last chance of stay'n alive.
:(

[Ruslan]

Foxmoth,
I'm not sure you did get it right, if the one didn't receive step-confirmation from other (e.g not working TCAS at all) no RA provided, TA only mode available (any TCAS guru around, correct me if I wrong). And my last note remains: you should LISTEN other traffic commands too.

TCAS2000 Brochure (PDF) (http://www.l-3com.com/acss/products/pdf/tcas2000.pdf)

but not in full details, sorry
(please don't take it as advertising)

[Alpha Leader]

The district attorney in Bülach (whose territory includes Zurich Airport) has opened an investigation into Skyguide. Charges are involuntary manslaughter and negligent interference with public transport.

As the mid-air crash physically occurred in Germany, Skyguide is the only Swiss target for any criminal investigation.

In addition, one of the serious deficiencies outlined in the recently published report by BFU, the Swiss Air Accident Investigation Bureau, is coming back to haunt Skyguide in the context of Monday’s mid-air collision, an issue confirmed by Jean Overney, the bureau’s top manager.

The report, released on 26 June 2002, had – among other points – highlighted shortcomings in Skyguide's time stamping and legal recording of events. The report says that “our investigations have revealed that the recording of flight paths by the legal recording system and their representation on controllers’ screens can differ”.

Investigations carried out by the Swiss Air Accident Investigation Bureau following Monday’s mid-air collision have confirmed that the available legal recordings do not “in every aspect” concur with the situation as described by the duty controller.

[vertigo]

So, it now looks like the controller was very busy. Does anyone know the manning at Zurich centre on a night shift ? Were they working all the Zurich sectors 'band-boxed' or were there other sectors open ?
If the 'standby' controller had come back and plugged-in would there have been any other cover available ?

At the London Terminal CC, the availability of staff has a definite influence on whether I ask for a sector to be split. I know it shouldn't, but with present levels of staffing there is little option.

Standard Departure,
You seem very quick to critise our Swiss colleague by jumping to conclussions. Your description of someone hopping from chair to chair, making R/T calls without waiting for a readback would be laughable if the circumstances were not so tragic.

Have you never worked with two radar sreens side by side, frequencies Cross-coupled ? One screen set to long range, the other short range. All transmissions (A/C or ATC) are broadcast on BOTH frequencies and no, you don't even have to get out of your chair.

Speculation is healthy, it makes us think what we might do in a similar situation but please don't be so quick to condem someone who must be suffering terribly without at least THINKING of ALL the likely scenarios

[Standard_Departure]

Vertigo, if you took the time to read my posting properly, you would find that the focus of my critisism is directed at the ATC system, in this case skyguide;

And Skyguide, please don't tell me that this is also within your tolerance limits or acceptable standard operating procedures !!!!!
the bulk of the damage was done when they removed TWO vital safety nets, #1 the other controller & #2, the conflict detection equipment.

I am familiar with cross-coupling (of frequencies), also with long and short range screens in close proximity, but what seems to point away from this though, is the fact that the T154 was on frequency and in conflict with the DHL for 4 minutes before a decent instruction was given, what other reason could there be for the delay if all the functions were within arm's reach? I cannot be convinced that any ATC would consider vectoring an a/c to an ILS as a priority over an iminent mid-air.

Where were the coordination telephones for Friedrichshafen? at his own sector, or at another sector? (I am talking about the stand-by phones)

During the work on the radar system there was also some working on the telephone net of Skyguide. Therefore the main telephone line war switched off. For the radar controllers work a backup (bypass) line was available. When trying to establish contact for coordination with FDH technical problems occurred. Between 23:25:43 and 23:33:11 LT the controller tried serveral times to establish contact with FDH. He was not successful
Ref: Click here for the reference (http://www.bfu-web.de/aktuinfo-e28.htm)

Vertigo, I truly have sympathy for the ATC, I believe that even with the limited information available, it is clear that, the SYSTEM failed, not the ATC. All that remains to be seen is to what extent.

[TwinCat]

Sorry to intrude as I'm not in any way connected with your noble trade, but it so happens I have a few acqaintances in Ufa, Bashkiria, so I guess I have a right for a question or two.
1. Concerning the BFU report. My English is not so good as, say, Ruslan's, so I never realized that "immediately" means 90 sec. I can stroll 100m in 90 sec, let alone a plane. I mean the time between the last call to FDH and the first call to Tupolev.
2. As I see, there was a small but measurable time between the "TCAS descent" from DHL and actual collision. Was it possible to prevent the collision in this time or Russian pilots only are forbidden 14sec delay?
Thank you for answers in advance and please be certain I've read all the twenty-four pages of this thread (meaning some extra questions will certainly arise if people here allow).

[Martin A]

Thought I wpould take a look back at this later. Glad I did. Normal USSr transponder does not show on TCAS (many hours on LHR to NRT confirms this!) ANY mode A transponder shows on TCAS. If mode C available, then TA and RA available to a TCAS equiped aircraft. If target has TCAS, thne co-ordinated manoeuvres are possible Hence all that TA only when you go engine out, it lets you look at TCAS targets, but the TCAS equiped other aircraft now knows that you will not manoeuvre, i.e you are in a sort of listen only mode.
as to the ATC, the bandboxing has gone on for years, the increase in separation due to equipment limitations has also gone on for years and is quite normal and acceptable. What happened is what always seems to happen in the middle of the night. Only two blips on the tube and you just know they are going to meet, usually witha few thousand or so between them, but it really isa case of S**s law applying whe you least expect it. As to not noticing what was happening, possibly so, but bear in mind that with a near head on cross, 5 minutes before the crosss, the aircraft would have been about 80nm miles apart. Even at 1 minute it was around 15 or 16 miles, not overly generous, but not a hit. From the little I saw, they were on near head on crossing tracks, so with very little difference in timing, they could have passed harmlessly 7nm apart. That would have been hard to tell at 80nm, but probably a bit more certain at say 20 to 30. From my own experience (a long time ago !) one would try not to climb or descend cruising aircraft at altitude, mainly because the option of climb may not be available. If you could keep everyone in level flight it would seem to be a better service.
This has indications of a combination of technical and human factors which will not be half as easy to solve as we may think.
As to TCAS manoeuvres, they are only vertical, bearing accuracy is low (+/- 5 degrees), but with refresh rates better than ATC radar. All to be done in vertical no GPWS pull ups, as you normally only need about 3 to 400 ft change of relative flight path. Turns not always a good idea. A 747-400 tried this at near maximum altitude, lost a couple of thousand ft in in over enthusiatic attempt and did not help anyones adrenalin level ! With the bearing inaccuracy, you could actually turn into the traffic. Possibly OK if you also keep the VSI where it should be whilst doing it, i.e. follow TCAS basic but add lateral. As someone said though, lateral is hard to achieve in a short time with risk of control problems at near max altitude, vertical much better.
Moral, stick to TCAS manoeuvres as they are published now. Maybe they will change maybe not.
As to what was happeing in the control room, maybe someone familiar with the set up in ZRH can speak, but with all respect to my fellow pilots, unless you have been there (working or with a lot of familiarity of an ATC unit) it is difficult to comment in specific terms as to what and how things should be done in a particular unit at a particular time. What was happening as described earlier seems quite reasonablt to me, no different than ony other unit operating at those kind of traffic levels.

Regards
MArtin A

[Standard_Departure]

Martin,

Good posting, very considerate too.

There are some (many) things that remain un-asked and/or un-answered. As an egsample;

Assuming that the aircraft collided at an intersection of two airways, that intersection probably has a name or a fix associatedwith it. Were there any estimates passed for that position, and if so, how far apart were the estimates?

Was the ATC on duty starting a night shift, or ending an afternoon shift? How many continuous hours had he been on duty? In fact, how are the shifts arranged at Zurich ACC?

Statements made to the press seem to imply that these 2 ATC's were the only guys on duty at the Entire Zurich ACC, and one of them was on a break. Is this accurate? The entire Zurich ACC, ONE CONTROLLER ??

If there are any Zurich ATC's out there, could you (without incriminating yourselves) fill in any of these type of "Procedural" details.

Cya

[sky9]

Ferris,

Of course as a Controller you want to do something however I suspect that one of the Accident Report findings will be that having allowed the aircraft to get too close the controller would have been better to have done nothing. The DHL 611had already left its cruise altitude and was descending. If the BTC 2937 had done nothing (or followed TCAS) there would have been a very close Near Miss however there should not have been an accident.

In the past there was a theory that mid-air collisions during the cruise normally involved the same type of aircraft because of the instrument error in the altimeters was the same. I suspect that one of the side effects of RVSM is less instrument error, more accurate altimeters and more aircraft at exactly the same level.; the same way that more accurate lateral navigation has reduced the scatter of aircraft down airways.

Standard_Departure.

Estimates have not generally been given in Europe of some years. "Radar Contact" is normally the answer to the initial call.

[twistedenginestarter]

I've said it before, but how many more innocent children are going to die before someone gets rid of this World War 2 CB radio ATC nonsense that is so completely,..... completely,...... completely ridiculous???

TCAS is just a pathetic attempt to scratch at the edge of a simple fact. - WE ARE IN THE DIGITAL AGE

We all know it would take about 10 mins to specify what a computer controlled digital system would be like, and any IT supplier could deliver the thing by next year. Don't talk to me about Swanick - that was like someone trying to design an electric razor that looked like a human being with arms etc to manipulate a cut-throat. I couldn't do it so I'm not surpised they didn't manage to either. Note I'm not saying you have to do away with pilots, but perlease there is absolutely no point in a person trying to work out airliner ballistics in real time and then try to relay that at human speech speed/error rate across a crackly voice channel.

All we get is pilot studies, pilot studies and pilot studies.

And dead bodies...

[Pilot Pete]

If there is only one controller in the room, what is the contingency if that controller is in some way incapacitated? Surely this cannot be normal practice?

PP

[atakacs]

If there is only one controller in the room, what is the contingency if that controller is in some way incapacitated? Surely this cannot be normal practice?
Was about to ask myself.

Sounds wied, at best

[410]

A number of comments here from people who perhaps would do better to read the posts of those who actually know what they’re talking about. I’m referring in particularly to those who’ve suggested lateral manoeuvring in response to a TCAS resolution alert. (A seriously not good idea.) As for the person who suggested a 60 degree turn… I can only surmise he has never been on a flight deck of a passenger jet above 20,000’ – or sincerely hope he hasn’t.

From the number of ‘hits’ I see this thread has had, I’m guessing that a lot of people outside the industry are visiting this site hoping to learn what went wrong. To them, may I say please don’t take everything you read here as ‘Gospel’.

No single mistake ever causes an accident like this to occur, but a series of small errors, (many of which would be insignificant in isolation). People die when all those insignificant errors form an unbroken chain, the so-called ‘error chain’. That’s what happened on this occasion. Let’s hope the investigation concentrates on breaking any future error chain rather that playing the blame game – and breaking it far earlier than 90 seconds before a cataclysm.

[nippa]

We are getting quite tied up with timings in this thread.

Already it's been shown that SwissGuide's system has some inaccuracies and I've seen this within our own system ; where RT times are not the same as the Radar Recordings.

Because of the critical nature of these events , I trust that Swiss timings will be co related to timings of the German and French Radar recordings.

[Orca strait]

I've always viewed TCAS as another tool, much the same as Wx Radar. Equipment knowledge, interpretation and situational awareness by the operator is required with Wx Radar, it is then up to the operator to maneuver the A/C to avoid the "lumpy stuff".

Experiencing an RA in real life or in the sim while IMC, leaves you charging after a computer generated solution (escape maneuver) without visual / oral confirmation of some sort, and is disconcerting to say the least. Upon receiving a TA/RA, my first reactions are; check my altitude, eyeballs outside - then lights on, day, night, VMC or IMC. The gee whiz marvels of today’s technology are tools that still need old fashioned airmanship for backup.

Missing radio calls is nothing new, we've all done it, as our undivided attention is not always placed on that com box (aviate, navigate, communicate). A disturbing trend that I have noticed amongst aircrew is both pilots switching to I/C to communicate with the cabin, or both monitoring the ATIS while simultaneously monitoring ATC - seems simple enough - but maintain the S.O.P.

My above comments are in no way meant to speculate on the cause of this particular accident, only to bring forth some basic fundamentals that we should all look at as means of additional preventive measures as we continue to fly safely.

[Sagittarius Rising]

4 years ago I spent a wonderful few days with my old man out in Bahrain when he was one of the Skippers on the DHL 757.My thoughts are with the families and all the staff of such a friendly and professional base. I know that my father who recently passed away would have been devasted at such an unnecessary loss.

S.Lewis.

[Seriph]

Yes Vertigo I worry about Standard Departure as well. His ideas about lateral spacing from 'first hand jump seat experience' are bizare. Some of us are up there 900+ hrs a year and might know what we are talking about. Standard airways routings are frequently discarded, I've crossed the whole of Europe on a single direct many times.

[FL600]

The controller made a mistake like we all did at one point or another, whether it was forgetting an aircraft requesting a pushback or a late vector to final...This time Tcas was involved in a way it was never designed to be. Scary and so so sad. My understanding is that Skyguide is standing by the controller as to prevent a 72nd victim of this tragedy.

Yes one man operation in zurich ACC at night is normal staffing.

Many would love to manipulate this event for political gains and some might succeed. For me this is and will remain a tragedy that hits very close to home. It has been a difficult week.

[GearUp CheerUp]

The coverage in the newspapers of this accident have plumbed the depths of cheap sensationalism.

I was reading the Daily Express a couple of days ago where some **** had written an article in which he/she made the point that RVSM was putting everyones lives at risk by cramming traffic closer together in search of extra capacity / profit at the expense of safety.

Correct me if I'm wrong but in the days before RVSM altimeters were good enough for 1000' separation up to 29 000 feet and above that the separation had to be 2000'. RVSM approval is only granted to operators who can demonstrate that their equipment can give the same accuracy above 29 as at lower levels.

I wouldn't insult my backside by using this sort of 'newspaper' (I use the term generally) as wiping material.

[St_Paul_Island]

Regarding radio frequencies in Europe, I have often wondered about the logic of having to memorise 6 digits. As I recall, short term memory is only good for 5 (?) or so items, so one has forgotten the first few digits by the time the last ones arrive in the queue. At least that is the way it works for me and my grey cells.

Why didn't they change the last 2 digits into a letter code? A (alpha) could be 00, etc. This would provide 26 "spaces" within each 100, more than enough for now and also any future frequency splits.

Easier to say and remember "123.4romeo" than "123.456".

Of course all the boxes would have to change yet again. I'm foolish to think that anything would change based upon an anonymous posting, but I wonder why it wasn't thought of before.

[411A]

Seriph raises a very valid point IMHO....keeping to standard routings costs a little more time and fuel, but should be much easier for ATC to plan for conflicting traffic.

[Standard_Departure]

Seriph (with 900 + hours per year!)

Yes Vertigo I worry about Standard Departure as well. His ideas about lateral spacing from 'first hand jump seat experience' are bizare. Some of us are up there 900+ hrs a year and might know what we are talking about. Standard airways routings are frequently discarded, I've crossed the whole of Europe on a single direct many times.- (Seriph)

If you read the following two quotes from within these pages, you will notice NOTHING bizare about my experience.

There are still thousands of aircraft flying airways at any given time of the day all around the world.

The referal to offset routings applies to direct tracks and airways alike.

What exactly was bizare about my statement? (specifially please)

What's this hangup with offset routings Wiley. Who follows the routes anyway? As in the States direct routings are becoming the norm, the 'traditional' airways system's days are doubtless numbered. In any case how many Russian and other third world outfits have sat nav. Ever been on the flight deck of a 154? Out of the dark ages.- (Seriph)

The reason for this is (and I have first-hand jump seat experience) that navigational systems are now so accurate, that two aircraft routing in opposite directions between the same two positions actually (often) cross EXACTLY (as in wingtips virtually aligned) over and under each other. BY off-setting from the direct track or airway by 1/2 a nautical mile, both left or both right, there will be a natural 1 nautical mile separation between aircraft on opposite direction routings. This would provide a lateral (horizonatal) safety if the vertical seperation were compromised. (This would not have helped in the swiss incident however) - (Standard Departure)

....... or are you just looking for a fight ?

['%MAC']

St. Paul Isla,
5 is at the low end, a safe assumption. The research, (Weiner?) substantiates it as 7 ± 2. Way back before my time this was how the telephone network in the States was set up, for example Belleview 458. I think they found it really didn’t make much of a difference. If you give the numbers in packets of 2 they seem to be remembered better, so for your example: onetwo (pause) threefour (pause) fivesix. There is loads of research on this, probably too much to make any rational or timely decision.

[Seriph]

No Std Dep, I'm not looking for a fight just amused at your first hand experience from sitting on a jump seat. I can think of very few bits of airspace where everyone goes in the same direction, just look at an airways map of the eastern USA or Switzerland / Germany. At any time we can track TCAS returns going in all directions. It has been proposed some time back in the States that the conventioinal airways system be scrapped. Also you assume that all aircraft are capable of an accurate offset, not yet.

[Alpha Leader]

In one of your recent posts you mentioned Skyguide's own website and its statement of relevance.

Despite being nominally a private company, Skyguide is 99% owned by the Swiss government. Its board is made up of a curious mixture of people, such as Franz Kellerhals (Chairman) and Anton Menth (New President of the Swiss postal service) - both better known for having just recently brought down Tornos (a machinery manufacturer). Others are Christophe Keckeis (Second CIC of the Swiss Air Force), Josef Felder (Zurich Airport), Pierre Moreillon (Aerosuisse, a lobby group), Philippe Simon (Representing the Skyguide personnel) - each of them obviously representing vested interests in particular sectors of Swiss aviation. Finally, there was Peter Siegenthaler, Director of the Federal Treasury and member of the board of Swiss International Air Lines; having finally realized his own conflict of interest he recently resigned and is to be replaced by his deputy at the Treasury, Peter Saurer.

The point in all this is that Skyguide's entire business philosophy is diametrically opposed to any pan-European integration. In order to further cement its insular position, Skyguide has integrated both civilian and military ATC, a unique situation in Europe. No country would agree to having its military ATC handled by a pan-European body.

[Standard_Departure]

Seriph.

OK..

Sorry if I was not "clear"

Wiley was saying that it "needs" to get sorted, continueing that line, I agreed.

What I meant by my "first hand experience" was that I had seen how the modern accuracy actually put us directly over and under opposite direction traffic, and I mean exactly. The discussion in the cockpit at that time was exactly about that.

As an ATC, I watch daily (continuously) how, on airways, opposite direction traffic cross over each other on the exact same track (in opposite directions).

I also think that the off-set tracks (on direct routings between waypoints and on airways) should be built in to the navigational equipment.

I am not a pilot, but I see the advantages of this method.

I do not see how my statements were "Bizare"

Best Regards.

[The Crimson Fruitbat]

SD, I read your post on page 9 and thought it was pretty straight. Many posters are on the money with addressing the "accident chain" as opposed to nailing some poor driver posthumously (a common trait in the industry) or a controller.

However there are many prone to drivel that know nothing of ACC operations nor modern nav tolerances (or lack of as you have accurately described) as I noticed that you have described in your last post. For info, I did some research some time back into "offsetting" and at the time IFALPA appeared to condone it in some areas (eg Africa).

I have worked ATC dunnunda and now Nth America and have a degree majoring in HuFac (Prof Reason's or Helmreich's opinions might be too systemic after the forthcoming investigation and might not sate the blame hunters) and just thought that I'd give you my two bob's worth of support.

To the controller: may you find peace within yourself sooner rather than later...there are thousands of us around the world that deal with our own failures/foibles as humans, flawed procedures, questionable support/guidance from above, equipment failures/outages, "customers" non-compliance, their hearing but not listening, violation of instructions/clearances and and generally drivers not being aware of what it takes to keep the aluminium tubes moving with minimal separation (lack of SA/CRM "big picture") I (we?) hope you can get on with your life sooner rather than later.

There but for the grace of god go I...

[Ignition Override]

Maybe US TCAS facts have already been discussed on this thread.

As for US civilian TCAS requirements, only passenger planes have been required to install the expensive equipment, as far as I know. The FAA set a deadline for cargo jets to have it in the US, but FEDEX volunteered to install it in their jets. Did other US freight airlines also begin voluntary installation well before any FAA-imposed deadline?

Are many passengers on US airlines (or those on foreign planes over the US) even aware that the many cargo planes here were given a much later date for operational TCAS onboard?

Just a coincidence, but we were cleared for takeoff a few days ago in our two-engine passenger jet, with a 30 degree left turn (into a bright sun over Lake Michigan) from a very small upper midwestern airport's Runway 27 or 26, and given a turn towards a single-engine Cessna which left about three minutes before us. Both the tower and departure controllers never said a word about the traffic, not to mention its direction. Despite this, our assigned heading sent us towards the aircraft, passing it laterally by a half-mile or so on a parallel heading and a few hundred feet above. It was on our TCAS with relative altitude displayed, and the FO quickly saw it first (retired RF-4/F-4/F-15 fighter pilot) and kept us out of "deep klmchi".

Departure Control did not know what to say when I politely told him about passing the nearby parallel traffic, which we were not told about. Maybe the Cessna was not on the correct heading assigned, if any.

May Heaven help the survivors of the collision over Germany deal with their losses. I try not to even think about the poor parents.

[The Crimson Fruitbat]

looking at stats I'd ALWAYS be keeping good SA down your way...post - 9/11 traffic be damned, the system is close to overload.....hence RVSM

[410]

I don't think Wiley will object if I attempt to answer the question you directed to him, Standard_Departure, since this subject is my pet passion.

What's his (and my) hangup about offset tracking? It’s this: I'm constantly amazed at the dogged resistance so many people in the industry exhibit towards this simple and no-cost procedure that increases safety margins exponentially.

71 people have died to prove that the unthinkable can happen even in ‘First World’ radar-monitored airspace. Although I accept that my suggestion would not have helped in this particular case, surely the master plan should be to break the error chain as early as possible?

Anyone with a modicum of imagination who flys the line internationally has been expecting an(other) incident like this in Africa or elsewhere in the Third World since the last two major midairs involving large jet transport aircraft. (I refer to the IL76 and the Saudia 747 out of Delhi in 1996 and the USAF C141 and the Luftwaffe Tupolov (96?) off the west African coast soon afterwards.)

Both involved a large loss of life, particularly the Delhi accident, but neither involved large numbers of fare-paying Westerners, particularly Americans, so CNN didn’t run with them beyond the first few days and they were soon forgotten. And both were head on collisions, where the two aircraft did not, by a one in a million chance, (as occurred in the case we’re discussing on this thread), happen to unfortunately cross paths at the same instant. In both the other cases, the aircraft were on the same airway, occupying the same extremely accurate path across the surface of the earth, possibly for many hours, and it took just one mistake – for one aircraft to be at the wrong flight level – for a collision to become inevitable without split second, accurate and appropriate reaction on the part of both pilots.

Sadly, this latest tragedy has proven a point that I’ve been trying to make for some time now – that the reactions of even the most professional of us can’t be relied upon to be absolutely correct when a split second decision must be made. For God’s sake, ‘n’ number of times a day, we all approach other aircraft literally at the speed of a flying bullet. Is there anyone out there who thinks he can dodge a flying bullet, particularly if that ‘bullet’ may be manoeuvring unpredictably as well as it tries to avoid you?

I’m no Superman. I’d rather not have to manoeuvre if someone makes a mistake in what I consider to be the most likely scenario for the next major enroute disaster. If we all flew offset, we’d get a traffic advisory in the event of most conflicts.

So can someone answer me this: given that no one procedure short of grounding the whole airline fleet is a panacea that will cover all eventualities, do they consider it safer to have traffic approaching with a closing speed of almost 1000knots absolutely aligned with them in azimuth, or would they consider it safer if such traffic was offset one or two miles to their left?

[Farside]

I posted the followong article over two years ago, and since we have had enough close calls it is perhaps time to get serious about it!!!!! For once I am always on the right side of the airway and it is very reassuring to see 99% of the crossing traffic well clear on your left side!!!

How many more “Close Calls”

The attached file is a copy of an article that appeared in last week’s USA Today. It describes another near miss over Indian Airspace and casually mentions in it’s closing paragraph that there had been some 20 near collisions in Indian skies since November 1996.
Now it doesn’t need an Einstein to realize that one of these days it won’t be a near miss but a full hit.
With “Freeflight” and the implementation of full Fans still a decade away, are we just going to sit and wait for a disaster to happen. The Airway system and communication system over India (and many more places in the world for that matter) are completely outdated and not capable of handling today’s traffic volume. A friend of mine, who is a leading design engineer in navigation equipment, told me that he sometimes had sleepless nights realizing that the equipment designed today was so accurate that, used in the present ATC environment, would one day contribute to a midair.
We cannot sit idle and wait for some beancounting bureaucrat in organizations like ICAO and JAA to change and adapt ATC procedures to create a safer environment, and avoid such disasters from happening. We all know that changes will not come soon, and only after several disasters will somebody wake up and actually start to do something.
I believe, and have argued this before, that we should start a discussion to come up with some ideas and/or procedures as to how to implement the legal and authorized changes in the present system. With the many aviation forums that we have today, often used only negatively (i.e. PPRUNE/Avweb), let us use these forums to encourage positive discussions, resulting in policy changes, and increased safety.
For the time being, Offset Tracking is an individual choice, to increase separation, and is being used by more an more pilots (as per several articles in Flight International). But as long as these procedures remain someone’s individual technique, it might and will work for that crewmember, but is not used to it’s full effect as long as it is not an official procedure.
Offset Tracking, Parallel-Oneway airways, direct INS and GPS routes are all procedures that can be implemented fairly easily and without great financial inputs. Why is it not happening, and what are the political forces stopping it from happening?
Where do we start, and what is the procedure to follow?
The irony of the situation is that, while we are flying a multi-million dollar piece of equipment into the 21st century, screaming at the top of our voices over some outdated piece of HF equipment, trying with 100 other flyers to get our position known to an Indian ATC controller, you can step back into our luxurious passenger cabins, where every passenger today can swipe his creditcard through his individual armrest satellite phone and have immediate 5/5 duplex phone connection with anybody in the world.
I wonder if we have got our priorities right.

[Farside]

And to stay with it the following article was also posted by me on PPRUNE many many moons ago, so why don't we start it up again and see what we can achieve!



The recent mid-air between a Kazahk Il-76 and a Saudia 747 highlights a concern which we have been discussing between ourselves for months. While all the details may not apply; this disaster does dramatically illustrate
our concern.

The modern onboard GPS and/or DME updated IRS/INS navigational equipment has greatly enhanced the ease and accuracy of aircraft navigation. However, under certain circumstances, this accuracy could become a flight safety hazard.
Airline pilots spent untold hours EXACTLY in the centre of their 10 mile wide airways guaranteed only 1000 or 2000 feet separation from opposite direction traffic.
If there is a mistake during an altitude change by the crew of either aircraft, by the controller, with the communication between the two, or an autoflight equipment failure -- a disaster may occur..

FMS navigation computers should be off set just 1 or 2 miles to the right of track. This would guarantee 2 to 4 miles lateral separation between opposite
direction traffic while all aircraft would still remain well within airways.
This would utilise the extreme accuracy of onboard navigational systems to both remain within airways and to provide additional traffic separation.

Had both aircraft been equipped with TCAS, the Delhi disaster would have been prevented. However, all aircraft world-wide are not so equipped.

Airline pilots almost daily will pass another aircraft with this 1000 feet clearance. Wouldn't it be much safer to also have at least 2 miles lateral seperation? Since equipment and people do fail, why not implement this fail-safe technique?

[arcniz]

One question that should be asked in the dissection of this catastrophe is whether the for-profit (or at least 'no-loss') oriented goals of Skyguide caused fewer people to be applied to the ATC watch than would have happened if a Federal bureau were running the shift.

The growing trend toward assigning final responsibility for national priorities to Non-Government Organizations in nations around the world is worrisome if the approach leads to cost-cutting in the wrong corners.

Having a supervisor on that ATC shift would cost well under 200K Sfr per annum....adding a different perspective and another set of ears and eyes. The settlement costs will undoubtedly be more than 300 million Sfr, suggesting that more than a thousand years of the third-man's time would have been comparably cost efficient.

I cannot help but think that if the Eidgenossiches Luftamt were running the operation, a supervisor would have been there - as a matter of course - to help out, and those children, the crews, and others onboard would be alive right now. Maybe these NGO's with their cute marketing names and highly artistic logos and politically padded managing boards are not such a good deal, after all.....

[Latte tester]

Yesterday, flying from LSGG to LFPB, level at FL260 I watched, intently, as a TCAS target cruised by, in descent, inside 2 miles 500 feet below.
I was VMC at the time, but just on top of a layer, the target was well hidden in the clouds.
I might add that I was given a left heading change to fly in behind said target, but no traffic information was given to me, I can't speak for the other guy/gal.
Is this 'the norm' for Europe now? No traffic information because everybody is 1000' apart (ish).
This is the second time that this similar thing has happened, the first time resulted in a TCAS RA to descend because of a target descending head on. Again no traffic info until we asked the controller, just before receiving the RA.

Maybe procedures need to be improved...

I much prefer FL 430 and above, it's just a bit exciting on the way up and down.

Having said that, I must add a 'well done' to the female Paris arrival controller, loads of inbounds, parallels at LFPG and a bunch of us into LFPB. She had 'it' together.
It is still comforting to know there are people like her around.

Latte time :D :D :D

[411A]

Personally believe that the safety implications of RVSM in European airspace (not on oceanic tracks) have not been fully appreciated, and coupled with the accuracy of onboard nav systems of today, will lead to many more "problems" in the future. My opinion only, but the trend seems to be fully established.

[Devils Advocate]

I did a flight to Turkey last night, and whilst sitting there in the dark in the FL300's I watched (for nearly an hour) what could at best be described as an unerringly accurate 'line-astern' formation being kept by the four aircraft in front of us - it was a visually fabulous example the accuracy of IRS (and GPS) navigation.

I too have to agree about including an 'offset' in as much that it surely can't hurt - albeit that some earlier version FMC's don't support this function.

But how about also turning 'right' (as we used to) when you get a TCAS RA ? The point being that if TCAS has determined that a line-of-constant-bearing (LOCB) exists between two aircraft and as such there is a risk of collision - which it attempts to resolve by telling one aircraft to descend and the other to climb, so providing vertical separation - it has not resolved the fact that both aircraft are still on a line-of-constant-bearing from one another, i.e. get an RA in clear skies, you descend, the other fella climbs, you might very well find that the other aircraft goes literally right over your head - chilling stuff !

So why not also attempt to break the line-of-constant-bearing - by having both aircraft turn as well as also comply vertically with any TCAS RA instruction ? Surely the logic for this could be built into the TCAS software ( and one would imagine that modern computer processors should be more than able to cope with doing the maths ) and thus as well as having the vertical separation you'd also hopefully be breaking the LOCB by having the TCAS co-ordinate 'roll' guidance to the Flight Director(s) on each aircraft - and whilst we wait for such a mod to be actioned why not have a SOP that dictates that in the event of an RA climb or descent you should also turn right by (say) 45 degrees ?

Uhm, now would this have helped over Germany, e.g. if the B757 had not only been descending, according to its RA, but also turning 'right' ? Well at least it would have been trying to break the LOCB and they might have then missed each other, though maybe not by much - but a miss is a s good as a mile.

Of course I'll admit that adding extra functionality to the TCAS logic will cost money (i.e. lots), but what price does one put on the lives of an aircraft full of children ?

Ah well, it's just a thought, any takers ?

[411A]

Absolutely spot on, Devils Advocate, IMHO.
Is it likely to happen?....don't hold your breath.

[Standard_Departure]

Can anyone tell me if there are any present or future plans that will allow autopilot to "execute" TCAS RA's, so that the Pilot must override the manoeuvre should this be required?

[garp]

Devil's advocate,
Perhaps you should wait to see what the exact tracks of the concerned a/c were just before impact. Perhaps you will see that one of the two a/c made a turn. I suppose it will not take very long before the charts with the plotted tracks will be released to the public. After that you might want to reconsider your proposal.
Garp

[Standard_Departure]

Ho hummm,

Methinks that garp has inside information ??

;)

[garp]

Latte Tester,
I'm sure that if you don't get any traffic information it simply is because the controller has other priorities. Whenever possible I will give traffic information but when it gets too busy you have to throw that overboard. Establishing separation is the main goal, getting traffic information is like receiving the Cognac on the house after a good meal, nice gesture but you shouldn't expect it every time you go to the restaurant.
Garp

[Standard_Departure]

The Dubai CTA has recently changed, instead of one big airspace, it has been split into Arrival and Departure Sectors. These sectors are spread all over, some arrival sectors on top of departure sectors, some departure sectors on top of arrival sectors, and some sectors that are vertically exclusive to one or the other.

The point is, there are often times that aircraft are descending or climbing toward other aircraft that are not on the same frequency.

To avoid the pilots continually asking, or at least to allay concerns about the TA they are just about to receive, I will attempt to always give traffic information, including relative bearing, distance direction of cross and restricted above/below.

This seems to work best all around. (But as garp says, when the frequency gets loaded, that the first to go)

[ferris]

I have been thinking about this accident a lot, and the one thing that stands out to me is a system whereby at some indeterminable point, the two aircraft were operating under different control regimes at the most critical time. That is, it appears the TU was under ATC, and the DHL was under TCAS.
That, to me, is the fundamental flaw.
What currently happens is everyone accepts ATC instructions until some point where they take matters into their own hands, and as we have seen, that didn't produce the required result.
In the few brushes with TCAS that I have had, the situations were resolved by the aircraft reporting 'TA' to me, then me providing the info and what the plan was. In one case, the a/c BOTH ignored RA's and followed my instructions (and ended up with a much better result- in my opinion).
I don't think anyone doubts that if the RA had not been complied with, there would have been no crash.
Maybe this aspect should be focussed on; as someone else said "TCAS used as an AID, not as gospel"

[Devils Advocate]

garp - it will indeed be interesting to see the tracks ( uhm, so how come you're privy to them then, and will they pop-up in the ATC forum perhaps ? ;) ). That said, would you please explain how it is possible for two aircraft which are apparently on a collision course (LOCB), at which if one or both turn right ( to remove the LOCB) that they can still hit each other ? (given that they're roughly doing similarly constant speeds, etc); and why, for years, if a collision risk exists (LOCB) have pilots relied on each other to each turn right (to take away the LOCB) in order to avoid hitting each other - or was this just BS ?

Maybe what you're alluding to is that if ( and I'm HYPOTHESISING here ) two aircraft (A & B) are on a collision course, each gets a TCAS RA, aircraft A descends, aircraft B should climb but - for some reason known only to its crew - also descends, aircraft A turns right, aircraft B turns left, both collide - this is known as the "You're having a very bad day - aka. Sh!t Happens !" scenario.

[BOAC]

D A - TCAS does NOT use bearing information. Cpt Pit Bull has posted some excellent info here and on tech log about TCAS which you should read. The bearing info (often not reliable) is to aid YOU in visual acquisition of target. It works on closing rates, range and altitude differentials, and has NO concept of collision courses except that on such, at conflicting altitudes, the closing rate and range become significant. You do NOT have to be on a collision course to trigger an RA - only the separation minima have to be threatened.

Regarding turning to the right - what if the target is slowly closing with you from the right hand side on a converging course and alongside at your altitude - say half a mile away in cloud?

[garp]

Imagine the scenario were you have a very fast jet (500kts) and a slow moving turboprop (200kts). Bearing in mind the inaccuracy of TCAS in the horizontal plane would it not be possible that the jet by turning right would go straight into the turboprop. Let's say they're 10 NM apart on a 90° angle. A turn of the jet would bring the two together since the turn to the right of the turboprop is barely doing anything due to the slow speed. If they would keep their headings the jet would be flying ahead of the turboprop. Please correct this theory which I have seen many times in practice.

Garp

[Standard_Departure]

I cannot wait for the wide implimentation of VDL Mode 4, I suspect that apart from some other really neat features, the whole concept of ACAS's will improve in leaps and bounds.

[Ghostflyer]

Having spent half my life trying to create collision geometry prior to releasing a weapon or entering a visual merge, air-to-air geometry has been of more than a passing interest to me.

I am a great believer in offset tracking (lets do it) but it only helps in head to head or head to tail passes. With other collision geometry it may turn a miss into a collision or vice versa, it just moves the collision point randomly.

As to semi-circular levels, they don't always help either, 2 aircraft can both be at perfectly legitimate semi-circular levels and still be on a collision course.

Visual aquisition out of the window is very useful for lateral deconfliction but not necessarily for vertical deconfliction. Next time you fly down an airway watch the opposing traffic a level below you visually. It will always appear to be slightly high on you until the sightline rate breaks and then it will pass below.

Lateral deconfliction is a simpler thing visually. If an aircraft is stationary in the wind screen you will hit him; if he is at the same level. To break the collision all that is necessary is to turn towards his aircraft to generate a sightline rate. Turning right doesn't work all the time unless you both do it.

As an aside, you also have to be certain that you have acquired the right aircraft in our ever denser ATC environment. I know of one mid-air where the pilot concerned was looking at what he thought was the conflicting traffic as he hit his wingman. Those 2 aircraft were over 2 nms apart.

So what are the keys to collision avoidance. Well this accident seems to be the classic unbroken chain.

The 2 aircraft were at the same level.
The Swiss controllers collision warning system was turned off.
The collision geometry was perfect.
There were communication difficulties.
Neither aircraft saw the other except on TCAS.

If any of these links had been broken the accident wouldn't have happened.

Of one thing that I am certain, sitting in the cockpit with the lights down on long-haul flights is not the answer. After quite a short period of time attention drifts and then empty field myopia sets in because there is nothing to look at. Shortly there after everyone on the flightdeck is asleep.

During the day, even with an Air Defence radar showing where the target is it is very difficult to see it, if it is on a collision, until the Target Designator Box in the Head Up Display becomes active. (TD Box - A circle that surrounds the point where the target is in space to give a visual acquisition cue.) Guess what, fighters point at other aircraft to avoid visual detection.

On a clear night visual detection is easier but it is hard to establish where the aircraft is relative to you if it will pass close by. The other drawback is that if you stare at the sky long enough all the stars start to move and some of them appear to have anti-coll lights. (Whoo get the straight jacket out) Put a cloud in the way and you are stuffed anyway.

In an airliner you are worse off. The radar isn't telling you where the target is TCAS is. Sadly, TCAS does not have particularly good lateral resolution which could lead to you looking out the wrong side of the aircraft based on a TCAS cue. The vertical resolution is good and one of the keys must be to monitor the TCAS display and listen to ATC instructions that are given to the aircraft around you. But practice like the fighter mates do! Use the TCAS to acquire other aircraft visually. Find out where to look for an aircraft that is 60° left on the scope and 4000' low but climbing at 25nms. The more you do it, the better you get. Then you will have a better chance of spotting the intruder when you really need to.

The best way of building situational awareness is not to lose it in the first place. In a dense air traffic environment it is essential to listen to the other aircraft on freq around you and try and work out what they are doing. But even that won't work in some airspace, try blundering through Bombay's airspace, at night, during the monsoon, whilst trying to talk to the mighty Mumbai ATCers on HF. The chances of you having a mental plot of any aircraft within 1000nms is zero.

If you do spot that the TCAS shows an aircraft at your level and it looks like a collision start talking about it. Don't assume, check! If you have the room in your airway to take avoiding action laterally do so. If not ask for it. If you are still uncertain do something, being alive and having to write an ASR beats the alternative. Remember the rules only work if every one folows them, when someone has dropped the ball that is the time to earn all that Flightcrew dosh. If you are an ATCer feel uncomfortable whenever blips might have to merge on your scope and if you can avoid it do. Nobody really cares how slick the feed in is as long as it is safe.

The bottom line is that this is an unfortunate avoidable accident. Had anyone of the players involved spotted what was about to happen and taken timely avoidance action we wouldn't be discussing this now. How often do close airmisses generate this kind of response.

All that we can do is send our condolences to those that have been lost but then as professional aviators make certain that we try to avoid the same mistake in the future. I don't know whether I would have done anything differently were I in their shoes. What I do know is that quite often the information is there but it is either missed, ignored or in the worst cases not acted upon until it is too late.

As they used to say in Hill St Blues, 'Lets roll and lets be careful out there'

Ghost :(

[Standard_Departure]

Ghost

Good Posting, thanx

[Devils Advocate]

W.r.t. what if the target is slowly closing with you from the right hand side on a converging course and alongside at your altitude - say half a mile away in cloud? - surely in that instances the potential infringement of the TCAS bubble around each aircraft will cause a RA - where one should climb and one descend - so making a turn should have very little effect on that.

Also, and certainly when two aircraft operate at fundamentally different speeds (e.g. fast jet versus turboprop - as posed by 'garp' ) turning might be inappropriate, but surely only if the aircraft stay at the same altitude (which is what TCAS is supposed to prevent).

All I'm wondering is that where aircraft are subject to a RA, and as such they should be diverging w.r.t. their altitudes, would a turn maybe also be of some value - albeit not in all 'normal' RA instances, but instead just perhaps of benefit for those instances when somebody does not comply with their RA - after all, what we're looking at here is a scenario where ATC has failed to keep you apart, TCAS is telling you both to do something but one of you isn't, so what other choices do you have ?

Admittedly though, there's no two ways about it, but due to the 'uncertainty' of the position and movement of each aircrafts respective TCAS bubble - certainly from the perspective of the pilots - it's probably a tough choice as which direction you should turn, if at all.

Of course if the answer is to throw technology at the problem maybe what's really needed is TCAS that's hooked up to GPS (make it compulsory) that way you'll get highly accurate heading, speed, height information and as such the TCAS unit should be able to triangulate a position and so produce a more appropriate RA maybe with 'roll' guidance - uhm, would we then still need ATC ? …… only kidding ;)


Ps. (hence the edit) Ghost - bravo, an excellent posting !!!

[Seriph]

Ah we are down to the sanctimonious and self rightous preaching for which these forums are noted. Experts suddenly everywhere, so you can't stay awake with the lights down eh Ghost, prefer to insulate yourself from your environment, well it's your choice but don't preach it as gospel. As for lateral separation, I crossed France yesterday on three directs, crossing traffic and opposites everywhere, how do you arange offsets? and if everyone sticks to the airways then you just congest further.

[Ghostflyer]

Seriph,

Nope I'm not snctimonious (see can't even spell it) or self righteous, I don't know if anything I have said helps but I hope it does. I do know of a lot of sanctimonious arrogant 'professional' pilots that go around with there head up their own a***s rather than try to learn from others. They spend their whole days bitching about problems without ever trying to make anything better.

I have learn't a lot from the contributions of other people on these forums and if just one snippet prevents anything like this from happening in the future, I for one will be greatful.

What would you have done put the blinds up and prayed to the big sky principle. Sounds like the sort of preaching that went on in the dark ages.

Holy s**t, I just bit..... oh well feel better now,

Ghost

Mr DA,

The closure issue is interesting but effectively all that happens is the exact collision point moves. I once tried intercepting a Sea King doing 80 kts IAS with a ground speed of about 20, it was a a horrible nightmare only to be discussed in the bar. Against slow speed targets, any avoiding action by you ensures a wider miss distance.

Putting the boot on the other foot, lets say you are in a turbo prop and configured whilst trying to avoid a fast jet that is not on your centreline but still on a collision. A turn towards the intruder that points your nose behind him uses his speed and geometry to create the miss. You have to turn more than he would to get the same miss distance because most of the closure rate is being generated by his platform. However, if you both turn it can get mighty confusing hence the right hand traffic rule. The key is to do it early and decisively so everyone knows what is happening and more importantly share your information with the controllers.

As to turning to avoid a collision to provide a 'belts and braces' miss once all else has failed; it depends on when you do it. If you have TCAS or visual SA of the approaching threat and can clearly see how to avoid him then taking that action early, even before a TA cannot be a bad thing. If he is stationary in the windscreen and the TCAS shows him at your altitude even a slight turn at range helps immeasurably.

Getting to worst case scenarios, even a 10° turn that generates a line of sight rate will produce an acceptable miss distance if actioned when you get the TA. On a head to head at the TA (40 secs to impact) assuming both aircraft at 0.8 mach you have 16 miles per minute of closure.

So if you actioned the turn at the TA and had it completed with 30 secs to go ( 8 nm) you would miss the other aircraft by about 4,000 feet laterally using the 1 in 10 rule.

If you wait to start a turn until you get an RA at about 25 secs and again took 10 secs to recognise and complete the turn you you would get a miss of around 2,000 feet laterally but at some cost of vertical performance.

Warning To do something this late, you have to be certain that you are carrying out the right action. For that to be the case you must have sound SA.

If you really do have the SA though, do something early! Don't wait for an RA to make your move. Avoid the TCAS conflict completely if you can by firstly talking to ATC and secondly maneuvring. By the time you have got to an RA you are in an emergency situation and want to have the entire kinematic performance of the aircraft available to you in the vertical plane.

My companies SOPs say try to acquire the aircraft visually if you get a TA but do not attempt to maneuvre based on a TA alone.
Well if I got the TA, spotted the traffic, assessed the geometry as a collision that would result in a subsequent RA and could turn to avoid it, I would. (But you don't have much time and again you have to be sure and decisive.)

However once I got to the RA, I would follow the TCAS commands religiously in case of coordinated avoidance. Some trainers will say take the time to disconnect the AP and turn off the FDs in the time between the TA and RA, boll**ks get your head out and try to sort the problem out.

Quality decisions are normally made in good time, the TCAS conflict scenario is something that can be avoided by timely avoiding action at range. Like most of us I listen to traffic climbing and descending and try to tie it into TCAS returns around my aircraft. If we do have the SA it is essential we give that to the men who can fix it in good time - ATC.

If used correctly with the display range and altitude coverage set correctly and if we regularly scan it there shouldn't be too many surprises. Almost always the intruder will have been in the TCAS display system for some time before generating a TA. In the future I know that I will be taking as much interest in the TCAS approaching waypoints as I do now when I get into terminal airspace.


Ghost:)

[HotDog]

I was severely admonished by my captain one day in cruise east bound for reading a newspaper between my regular panel scans. Reason given was degregation of lookout alertness. Next day after an overnight stop in Japan, we took off and climbed to cruise level west bound late afternoon, whereupon same captain plastered his windscreen with his Jeppeson enroute charts to keep the sun out of his eyes. I must admit, this was before the CRM concept. What to do?

[BOAC]

Going a bit off an important thread, here, HotDog, but to answer your point - keeping the sun out of one's eyes degrades SA a lot less than reading a newspaper.

[vanman]

I have to say that the argument for flying a couple of miles right of each track as an offset sounds so obvious and relatively easily accomplished I can't understand why it's not already here. TCAS is rocket science by comparison. It clearly would not have saved them in this case though, as the two a/cs tracks were basically 90deg off (Skyguide press release picture of a/c tracks (http://www.skyguide.ch/img/photos_presse/skyguide-map-detail.jpg) )

Ferris recently said:-

What currently happens is everyone accepts ATC instructions until some point where they take matters into their own hands, and as we have seen, that didn't produce the required result.

No - they accept ATC instructions until ATC fail them, then they (must) put there faith into the TCAS only. It would seem the conflict between TCAS and controller instructions may have caused an incorrect response from one aircraft. The controller had been informed that TCAS RA was being actioned and at that point I would argue he should have said no more until the conflict was avoided.

In one case, the a/c BOTH ignored RA's and followed my instructions (and ended up with a much better result- in my opinion).

Hmm. Don't be too alarmed if I chose to ignore your 'advice'. This is exactly the type of situation which could generate another such situation. Don't forget that, if as Standard Departure (do your mates call you Sid?) said:-

An important thing to remember, is that as ATC's, we get a reduced re-fresh rate (sweep update) on the SSR, that is to say relative to the aircraft equipment, and it may well transpire that what you and I see on the Mode C readout is out of date by 5 seconds, and could imply that aircraft have already crossed levels and cleared each other.

...then I for one will take my chances with the TCAS and Mk1 eyeball thanks.

I for one found an urge to re-read about TCAS in the light of this sad event. (can't think why :)) Found this Honeywell TCAS II Pilots guide (2Mb) (http://www.honeywelltcas.com/pdffiles/tcas2guide.pdf) very useful, others may too. It certainly confirms that an a/c will receive an RA (not just a TA) if the other a/c has unserviceable TCAS but functioning transponder (mode C).

Also worthy of note is that a pilot is expected to react within 5 secs to the RA and only 2.5 secs to the RA reversal (which would presumably have been received in the 757 during the original TCAS descent). Possibly particularly useful info for Orca Strait who said:-

Upon receiving a TA/RA, my first reactions are; check my altitude, eyeballs outside - then lights on, day, night, VMC or IMC. The gee whiz marvels of today’s technology are tools that still need old fashioned airmanship for backup.

...just make sure you do it quickly, it might be me coming the other way.

Lastly, there have been serveral enquiries (including my own) about what happens when only one controller is on duty (should he become incapacitated (as this poor individual probably was after watching this disaster unfold before his eyes). Not much of a response as yet, anyone do better?

Cheers

[purr]

regarding aircraft closing in at an angle the solution has been around for some time in the shipping corridors infact officers have an oral exam on this and the same procedures are in force the world over .

[ferris]

VANMAN,
You have missed my point.

And in the case where the aircraft ignored the RA, it was FULLY UNDER CONTROL. Both had traffic, the descender was stopping above the climber, which was stopping at the level below. Both understood the plan. Their TCAS' wanted them to cross levels by steepening the dive/increasing the climb. How can that be safer?

Surely jumping in at the TA stage, having your situational awareness on the job, and controlling the situation is better than blindly following an unexpected RA? Not always possible, granted, but preferable. What I was getting at is the UNCONTROLLED way in which you opt out of the ATC system at present. I haven't put a lot of thought into the solution- maybe a button like the ident which you could hit at the same time as reacting to the RA which would announce to all, ATC and the other aircraft involved, that you were RAing?

[ferris]

And reference incapacity; controllers will tell you you must always have a replacement in the building. Managers (beancounters) answer is that you call someone in if that eventuality arises. They may even have a plan for the 'service outage'. It just depends who is the industrially stronger;)

[hkgmjq]

it's a shame my first post is written in disgust.

I've been reading and learning from pprune forums for several years now, and not being in the industry have been content to observe and keep my mouth shut.

But tonight I feel obliged to send in this link as yet another example of the appalling journalism that tends to swarm around such terrible accidents as these.

news.bbc.co.uk/hi/english/world/from_our_own_correspondent/newsid_2099000/2099421.stm

if that doesn't work, the article is currently on the bbc news homepage under the 'grief amid the wreckage' title.

Sure, there's eight million tons of crap written about aviation every day, but to have such gutless, provocative and cheap garbage come from the bbc is a new low, at least for me.

It needs to be seen to be believed.

[Standard_Departure]

Ferris,

I feel compelled to say that I think you have big balls to persuade one aircraft to "ignore" an RA. :eek:

I cannot even begin to describe the ability it must have taken to get TWO aircraft to "ignore" their RA's. :eek: :eek:

There I was, thinking that if the pilot's did not respond to RA's within 5 -10 seconds, they would be .... history.

Personally, if I had allowed 2 aircraft to get close enough so that they had both got RA's, I'd let them follow their TCAS's and be happy to hear a "Clear of Conflict" report from either.

Sorry man, we just DO NOT have that power.

[Ghostflyer]

Ferris,

Vanman's point is key. You said 'it was FULLY UNDER CONTROL' sadly most ATC errors occur whilst the the aircraft is fully under radar control. I am not slagging purely, stating my opinion that we all screw up; even ATC guys. Most of the time though it is the pilots misunderstanding the controllers. We are fortunate in that we have 2 guys around to try to make certain that we trap the errors.

Anyone can point fingers and use Harry Hindsight to solve a problem that has already happened. (C'mon Seriph) I watch TCAS on a day to day basis as you watch the radar and the update rate is significantly higher on TCAS than on any search radar that I have seen in sweep mode. Short of getting a radar that has single target priority track on all the aircraft within its sweep; there will be a delay. (Bring on phased arrays!) We all look at a historic picture, the key is to recognise the picture offering the highest probability of reality.

All parties will react to the information that they consider the highest priority and that provides the latest information. For pilots that goes: Mk1 eyeball, other pilots Mk 1 eyeball, TCAS, ATC, PPRUNE.

For ATC mates (Have to admit my best mate is an ATCer, utoh) it will probably be secondary radar followed by primary coz the altitude recognition is better on secondary.

The info priority is moot, the bottom line is that ATC guys have the big picture and should see the disaster coming together earlier and that is their best time to intervene. The pilots see it all happen later and they will have less faith in the guys with the big picture as impact approaches. You are a very brave man if you think you really can solve the problem during the gravy strokes.

It is easy to start attributing blame but the chain was unbroken by all parties and the ATC mate, given good info from his sensors, had the longest time to solve the problem, followed by the pilots as the collision approached.

Ferris, you are absolutely right, mitigating the situation at or before the TA stage is preferable. Preferably at about 50 miles.
If ATC try to intervene at the TCAS RA stage they have either missed the opportunity to intervene earlier or have not had the chance. In most cases at this late stage they will only end up confusing the situation. (Ask any military Fighter Controller that has gone from a standard search radar to the ACMI, a GPS based real time information system.)

In the end game, the pilots are probably so cluedo and shocked, that the chances of you getting the message across in the last 20 secs are not high; therefore they will follow the most compelling (and most accurate) info be it visual or TCAS.

Getting my sanctimonious head on if everyone had done ther job perfectly, this accident would probably not have happened. Sadly, it was a clear day in 1923 when I last flew a perfect flight, a hop in the Sopwith Camel. More likely I just didn't spot the mistakes.

The best thing to come from this, from my point of view, is that I have been forced to re-assess my way of working. Hopefully, I will incorporate some of the good ideas into my working routine that other mates (pilots and ATC) have presented.

Ghost

[vanman]

See what you meam HKGMJQ - and raises the ugly prospect ... was a third aircraft taken down by the fallout... The tail of the plane had sheered off from the main body of the aircraft and the jagged piece was lying beside part of one of the propellers.

...just a thought ;)

Ferris - I have to say I'm with STD_DEP on this. Whilst it does initially sound strange for TCAS to have the aircraft cross each others level, without much more info it's impossible to speculate. If crossing each others level would have kept them apart in 4 dimensions then, whilst it's not how you might have handled it, it will do it's job. Your job finished (rather unsuccessfully in this instance) a few seconds ago when the RAs were announced.

Either TCAS is to be be used or it isn't. Either it works and we put our trust in it, or it doesn't and we don't. Clearly 'the powers that be' believe TCAS to enhance safety or we wouldn't have it.

What this accident seems to have highlighted is that once the situation has deteriorated to an extent where an RA has proved necessary, then further controller input is counterproductive and dangerous.

It would seem though that a better system for making the ATCO aware of the moment when the TCAS has overridden his control must be found if he/she is to confidently keep quiet at the necessary time. We all know that there are times when one has to wait 30secs or more to transmit on frequency especially in busy airspace where an RA might be more likely. There will be many RAs where the first the controller knows of it is when it has already occurred, given the current vaguery of the notification process. In such circumstances he/she may offer conflicting instructions in all innocence that the RA is occuring.

Who has control?

[arcniz]

hkgmjq You're putting us on, right?

The BBC story you reference is very emotional and dramatic, but that is not so inappropriate, given the circumstances. One feels that the author is trying to convey an immediate and personal sense of the scene as she witnessed it. Journalists are expected to do that.

She remains relatively faithful to the facts, as they are understood at present. An exception to this is the reference to 'propeller' - probably referring incorrectly to a piece of a tubine. The article does somewhat implicate Swiss ATC, but what it reports is consistent with information from various authorities that is now generally known.

On balance, I think it is sensitive and well written for the audience to whom they cater.


The really deplorable qualities of bad journalism that specifically ARE NOT manifest in the BBC story include:

a) fabrication of facts

b) false and misleading attribution of statements

c) wildly inappropriate what-if scenarios

d) baseless accusations regarding cause or responsibility

e) deliberately misleading or confusing information

f) using a tragic circumstance as an opportunity to grind on about some marginally related agenda or concept.

g) exaggeration and hyperbole of a nature that create a clearly false impression of the actual events

h) incorporating unnecessarily precise physical detail and gore to the extent that they may cause profound revulsion and fear among the general public

[Seriph]

Going round in circles aren't you boys, and extremely voluble ones from some. Basically obey ATC and if the TCASD goes of obey it! And of course keep your eyes skinned, very likely for hours on end. Lets give it a rest, we are way beyond the pale.

[GaryRay]

To All:
Here is latest news from Moscow ( not BBC story!):

MOSCOW, JULY 6, RIA NOVOSTI -The Swiss air traffic controller made gross errors while controlling the Boeing -757 and the TU-154 airplanes. On Saturday, head of the Russian State Civil Aviation Service and first deputy transport minister Aleksander Neradko reported to journalists details of the aircraft accident which happened in the skies over Germany. According to him, available results of the investigation show that the air traffic controller of the Zurich airport allowed the Boeing-757, flying at the level of 260 to climb to level 360 (10,970 meters) without paying attention to the TU-154 aircraft which entered the Zurich responsibility area at the level similar to the Boeing's and was flying the crossing route. Neradko said that "to all appearances, the controller did not notice that, probably being distracted by something else." According to him, 4 airplanes were controlled by him at the Zurich airport and he was operating two display monitors.
The first control message to the crew of the TU-154 aircraft arrived 44 seconds prior to the collision. The message contained the instruction to descend to level 350 and 6 seconds later the controller repeated his command. At the same time, flight recorders on board the TU-154 aircraft confirm that 10 seconds after the receipt of first message the crew reported that it started descending. After that the controller again repeated his instruction "but mixed up the side from which the Boeing was approaching: he stated that it was the right side though in reality it was the left one." The air traffic controller's dictaphone registered the Boeing's voice message that the aircraft was descending according to instructions of the airborne collision avoidance system. At that moment, the Boeing descended by 200 meters and turned out to be at the altitude which the Russian aircraft was already flying.
Neradko also reported that the collision avoidance system at the Zurich airport "was withdrawn from the program". He stated that "if it worked, it would have warned the controller of the danger earlier." In his turn, Sergei Frank, Russia's transport minister, told journalists that the tragic situation in the air was evident 5 minutes before the collision. According to Neradko, the investigating commission, which involves specialists from Russia, the US, Bahrein and Switzerland, is analysing the recordings of the voice and flight recorders.

[ferris]

St. Departure- I am sorry that you don't understand how TCAS works. There is an excellent thread on the ATC forum by Capt Pit Bull which goes into some depth. As for never getting them close enough... well, you are just ignorant.
In the circumstances where the RAs were ignored; a 737 after a test flight was cleared to F160, vs a Dash8 climbing to F150. The 737 had been 'manouvering vigorously', and was in a high rate of descent. The 737 reported the TA as the two approached, was given the traffic, then the DH8 was given traffic and the plan. They both levelled off at their cleared levels, after acknowleging they would. The DH8 then said "Oh, and for information, we had an RA". I asked the 737, and he said" Yes, we did too", but was obviously not saying anything earlier in order to avoid confusion and the paperwork. I chased up the reorts later- thats when I discovered the RAs had wanted them to cross levels- and learned that it will do whatever it thinks will provide the biggest sep.

Vanman, I am merely trying to get ATC into the TCAS loop. The thought that I might interfere and CAUSE an accident really frightens me. The radio isn't the best way, surely (and as has been demonstrated), maybe incorporated in CPDLC, ot the ident button idea. Automatically would be best. I don't know......

[mole]

I have read this thread throughout and learned a lot. I had not intended contributing until I read the above. I have to say this post makes me wonder if some people do actually know what they are doing. Ferris points two aircraft at each other when one is climbing and the other, I quote "The 737 had been 'manouvering vigorously', and was in a high rate of descent"

Of course the respective TCAS got worried and started shouting, what would you expect in these circumstances? Ferris please tell us why you allowed these two aircraft to point at each other especially when one was still apparently involved in a test profile. Incidentally I would imagine the RA to which you refer must have been of a very short duration and ceased before either aircraft had time to manoeuvre. Nothing at all to do with the "plan" just the fact that the aircraft did level off at their assigned levels.

[fiftyfour]

BBC lunchtime news says Swiss ATC has reduced movement limits by 20% until further notice.

[ferris]

Mole- you claim to be a pilot?
Who said I "pointed the aircraft at each other"? One was joining the STAR, the other was going to destination after departure. Aircraft "point at each other all the time", you clown. That's why there are controllers. One standard we use is called 'vertical'. That means when you cross you will be vertically seperated. The rate you approach that level is up to you. Imagine this "Easy captain, I think you are descending too fast...." bwahahaha.
The test had finished, but I guess the crew were taking advantage of no pax.
Think about what you post. I am trying to think of how not to be put in a position of contradicting RAs. Or it will happen again.

[Hold at Saffa]

By their own chronology of events, Skyguide reports that both aircraft were on the same Swiss Control frequency for between five and six minutes prior to impact. A mid air collision in European controlled airspace has occurred, the first since Zagreb, with disastrous consequences.

Having visited the Zürich AACC (Area and Approach control centre) several things strike me as incongruous within their rather surprisingly rapid efforts to deflect blame upon dead aircrew.

Controllers routinely occupy their sectors whilst maintaining a 'speaker watch'. No headsets are used, and local distractions are therefore amplified. Was the controller actually at his/her seated sector position from 2325-2336, or merely there long enough to answer the initial contact calls of first DHL at 2325 and then the Tu154 at 2330?

Why weren't either aircraft assigned a separation vector at any time from 2325, why was it left so late to descend the Tupolev? That it was left so late in attempting to separate aircraft at the same level, that a delayed response from the Tupolev is even as issue, is an indictment of the Sector Controller responsible.

I regularly operate in Swiss controlled airspace, to and from Zürich Airport, and within Zürich's area of responsibility, and find their usual standard of controlling to be among the finest in Europe. However, as seems likely from the chronology of this disaster, lack of attention by the Zürich controller was, at the very least, the triggering causal factor of this accident. Personally, rather than reduce ZRH AACC capacity by 20% as has been the Skyguide response, I for one would like to see compulsory headsets insisted upon for all European Air Traffic Controllers.

It is perilously easy to become distracted by local conversations (how many European pilots haven’t heard other conversations/laughter taking place in the background of ATC comms?) during even optimum periods of stress. The potential for disaster is, in my opinion, orders of magnitude greater late at night with vastly reduced alertness levels.

If the ongoing investigation does reveal, as I strongly suspect it will, lack of ATC attention from 2325 until impact at 2336, I find the haste in deflecting blame onto the TU154 crew, and failing to accept full responsibility, to be an appalling reflection on the management of Skyguide (Swiss Control).

We need to learn from this. Ducking lawsuits and seeking a redirection of responsibility is no way to further flight safety.

[BEagle]

An article in today's Sunday Times gives an interesting and detailed account of what appears to have happened.

But only the formal report will be conclusive.

(Edited because I didn't realise that it was not permitted to link to newspaper reports in this way - my apologies.)

[Standard_Departure]

Ferris,

I apologise, I misunderstood what you said, I thought that you were implying that they had both reported RA's and then you sorted it out from there .......

HOWEVER:

Your attitude about TCAS is dissapointing. By your own admission, they would have missed had you left them to their own actions (RA induced).

To treat TCAS as though it were a U$ 9.99 piece of equipment that was a waste of time and effort anyway, is not fair to the Aviation society.

The purpose of TCAS, is ultimately to save lives, and therefore it has (in concept) an obvious value to you and I.

The implication that ATC's should disregard any actions by RA, and try and work it out ourselves, may lead younger and less experienced ATC's to think that they might be able to do the same. You are obviously an ATC with lot's of experience, and I am sure there are younger ATC's that look to you as an egsample.

I don't think that we should willy-nilly write TCAS off, but rather try and understand it better, and, where we can, give positive input and value.

If I offended you previously, that was not my intention. ;)

[millhampost]

BEagle
Times on line is not available to computers outside UK -
I've just been asked to pay GBP39.99 to see the article you quote.
If it is indeed interesting and detailed perhaps you would reproduce it in full.
Regards.

[BEagle]

My apologies for trying to post a link to the ST. I knew that quoting from the paper by 'cut and paste' wasn't permitted, I didn't realise that direct links were not allowed.

Apologies again.

Incidentally, the article implies that the Swiss ATCO was struggling with a failed telephone system to a German airport at the same time as the conflict alert system was down all on his own. When he turned his attention to the impending collision, he had difficulty in contacting the Tu-154.

I wonder whether the Tu-154's first reply co-incided with the ATCO's second call ('blocked') and hence the third call was the one which the Tu-154's commander heard?

The CVR/FDR transcripts will probably clarify this possibility.

[ferris]

I am not trying to imply that TCAS is no good. Just trying to work out how it could be better. It's only getting busier and busier out there.
Sadly, TCAS did not prevent the recent midair.
TCAS' success is predicated on immediate action. I would hate to think I had muddied the waters in such an event. Lets face it, if those aircraft didn't have TCAS, they would have missed. Conversely, if the controller had said nothing, they would have missed. There must be a solution.

[PaperTiger]

Did anyone else pick up that reference in the Russian release about DHX611 being in a climb from FL260 to 360 at the time ?
Was news to me although I may have missed it before. Or did the Russians just invent it, like the phantom 5-minutes earlier call from the 154 ?

[MarkD]

The Tu-154 crew could be completely blameless, but the Russians are not honouring their memory if they are putting out false info in an attempt to bury Skyguide, which a proper investigation with true facts may do in any case.

Seems like "getting your retaliation in first". That said, the Russians would probably say the attention given to the three calls to the Tupolev, implying the crew were ignoring ATC, was cause for getting in some digs at the Swiss.

[FL600]

Climbing from FL260 to fl360 is as per Rome / Zurich ACC letter of aggreement. Flight was departing from Rome FIR hence climbing to Fl260. Really don't think the russians made it up.

As for the 20 percent cut in capacity, Kudos to skyguide on this one. The controllers are under very real additional stress. Their collective future might be on the line here. Remember that Syguide exists both in Zurich and Geneva due to delegated foreign airspace.

[Shore Guy]

Can someone please post a newspaper link that has the Sunday Times piece in syndication? Like to read it but not for $40 L.

[mole]

Ferris,

Thank you for your reasoned response. I don’t claim to be anything, I am what I am.

Someone who takes the slightest criticism so badly perhaps should reflect very carefully. The point I was making, as I am sure you are aware, is that when two aircraft in climb/descent are planned to level and then cross on minimum separation AND one of them has an enormous rate of descent then you should be preempting the obvious result. That means trying to move one laterally so they don’t cross (no longer pointing at each other!) Alternatively why not ask the aircraft with an excessive rate of descent to reduce it or stop 2000ft above the traffic. Either way you would have avoided setting off the TCAS RA in your incident and saved a few grey hairs on the pilots involved, not to mention your own. If you had asked the 737 to reduce his ROD and he declined then he would have been a total as$hole (and realised so after getting the RA) TCAS is a very essential tool and shouldn’t be messed with. If you point two aircraft at each other with high vertical closing rates aiming to stop them 1000ft apart you are guaranteeing a TCAS TA and very likely an RA as in your case. We call it airmanship what do you call it?

[P22]

mole

Surely the 737 should have seen the other aircraft on his TCAS and reduced his rate of descent to avoid a possible RA. That's what I call airmanship.

[mole]

P22

Totally agree with you, however in this case the 737 pilot obviously didn't show any so wouldn't this have been a very good time for some early ATC intervention? Ferris apparently believes he shouldn’t intervene for fear of a bwahahaha (whatever that might be) and I quote:

“The rate you approach that level is up to you. Imagine this "Easy captain, I think you are descending too fast...." bwahahaha.

What on earth is wrong with “reduce your rate of descent” we are asked to increase it often enough and I don’t recall anyone replying bwahahaha on such occasions.

If Ferris is happy to watch two blips closing rapidly laterally and vertically and doesn’t even consider the possibility of an altitude bust then he is a much braver man than I. When climbing or descending towards opposite traffic with a planned separation of 1000ft I will always reduce vertical speed prior to level off, it does avoid the pucker effect. I believe the majority of ATC controllers act in a way which demonstrates a good knowledge of airmanship principals, on this occasion I just think Ferris left it a bit late. The RA occurred just before he spoke so I suggest it is fairly evident it was too late. He originally cited this incident as an example of ATC intervention being better then following an RA. He subsequently clarified what he meant in a reply to Standard Departure. So I guess everybody is now in agreement: early ATC intervention is better than waiting for an RA to occur. Fortunately the RA must have stopped at the same time as the 2 aircraft leveled off so no harm done just a few grey hairs.

My point is this entire proximity event could have been avoided with timely intervention. Perhaps I should call this common sense rather than airmanship if I am to avoid censure by you once again P22!

[BEagle]

Flying as I do a 4-jet which doesn't (yet) have TCAS fitted - we operate under 'state exemption', unfortunately - we have an SOP to reduce climb/descent rate to 500 - 1500 ft/min before reaching 1000ft of any cleared level in RVSM airspace. People remember it quite simply - 1000/1000 to avoid causing TCAS advisories to other (properly equipped) ac.

[Stan Woolley]

P22/Mole

The 737 probably was not aware of the other aircraft until near the cleared level because the TCAS will only show 'other' traffic within 2700 ft above or below, too late to reduce the rate enough to prevent a TA/RA if you are climbing/ descending quickly.

Some aircraft do have the TCAS facility to look higher/ lower but any 737/757/767 I have flown did not.

[Flip Flop Flyer]

In keeping with the rules of this site I shall refrain from pasting direct quotes. Since it's in Danish anyway I guess only a few here would be able to read it. Anyway, according to the www.dr.dk news site, a Danish controller, who was alone in the ATC centre at the time of the accident, has been hospitalized with a nervous breakdown.

Also according to the news site, and this part is most likely journalistic guesswork, the controller was so caught up in getting a line through to Friedrichshafen that he "forgot" about either the Tupolev or the Boeing, or even both.

The Danish controller was on duty with a Swiss collegue, who at the time was taking a break.

I feel for the guy, even if an investigation should come to the conclusion that ATC errors was a major component of the events leading to the accident.

[ferris]

Mole- we all live and learn. But you should get your head into a centre some time, and see just what we can and cant do. (for info- for me to work out you have increased rate of descent, I have to be sitting watching the level changes on your label for a good 4 sweeps, something I don't necessarily have time for. Rates of descent are a nice-to-know, not a need to know once you have a standard in place).
We seem to have gone off on a tangent to my original intention, which was to point out that currently ATC doesn't know of TAs or RAs unless told about them.
Until that episode, I didn't know TCAS would issue RAs to CROSS levels, and when I found out it sent a shiver up my spine, because we are working to prevent that. It really scares me that I could be working to oppose an RA, whether that RA is necessary or not.
Hopefully something will come out of this Swiss enquiry. Surely it couldn't be too hard for the TCAS to tell the transponder to alter it's squawk when it issues an RA?

[Ghostflyer]

Beags,

I used to work for the dark side too. Current airline has an SOP to reduce the Rate of Climb/Descent in the last 1000' to avoid TCAS alerts.

Ferris,

There would have been no TCAS crossover requirement if the 737 crew had been operating sensibly. Period. Stay frosty dude!

In this mid-air it seems both aircraft had TCAS and so it is likely that if they had both followed co-ordinated RAs they would have missed (Nothing like superceding the investigation..). It isn't the box, its the implementation of its commands.

Beags,

Good job TCAS wasn't fitted to the Lightning just think of some of the commands that you could have invoked with proper Climb and Descent rates.

Ghost:)

[mole]

ferris,

Thanks for replying I think we are now on the same wavelength. TCAS is an excellent piece of kit but most of us do try to avoid hitting potential TA/RA trigger points by reducing vertical speed when approaching occupied levels. All I was trying to say was I hope you guys in ATC do the same when time permits you to do so (vectors when it looks tight.) TCAS is very neccessary and works well but only after the investigation will we know why it didn't do the job on that tragic night over the Bodensee.

[ferris]

No dramas.
You can squawk ident at the push of a button. Why not auto-squawk TA then RA (maybe with a manual overide option), so that ATC, and more importantly, your traffic, know that you are going to RA manouvre?

[Standard_Departure]

Ferris, I agree.

There should be;

1. Some way of ATC knowing that a/c are are on RA vertical Nav.
2. Regulations in place that mandate ATC response (or lack of) once they are aware of RA avoidance in progress, so that we can be (legally) absolved of Avoiding action requirements once RA avoidance takes over.

Sidenote: If I understand correctly, the advent of VDL Mode4 will greatly improve the automatic TX/RX if information between a/c and a/c as well as ATC and a/c.

SID

[Iron City]

VDL Mode 4 jury still out, I believe. Would be good to know the reliability and timeliness of this feature in the real world.

UA FANS equipage was, I hear, a bust.

There is some testing going on in Miami area, not sure if it is Center or TRACON

Eurocontrol marketing adverts say it is going in in Europe

My questions would be:

1. It is a VHF link, hence line of sight, what kind of infrastructure is needed to support it and when will it be in and do you trust your life to it.

2. how long does it take for a controller to create, send, and confirm receipt of a message by the intended addressee (or vice versa from air to ground)

3. how reliable is the VDL 4 link.

When the fecal matter hits the rotary air circulation device and the crew is dealing with TCAS RAs and possibly systems problems and trying to maintain the plot (excuse me, maintain situational awareness) the first thing they will want to do will be to type data link messages and read messages on the little screen ?

[sidonia]

In a recent anouncement to the press, the relevant german authorities stated that the TCAS of the Russian plane ordered the crew to "climb,climb" --some seconds later the ATCO in Zurich ordered the crew to descent immediatly with the phrase "expedite descent to FL 350".
Some more info to come later on in a press conference.

[End_of_Descent]

The latest data given at the BFU press conference is available on their German language news page by now. ( http://www.bfu-web.de/aktuinfo-d28.htm )

According to the BFU, both CVR tapes have been repaired over the weekend, data are in excellent condition and first results have been obtained.

Early investigation of the CVR tapes indicates that both TCAS systems were working properly. About one minute before collision (times are not accurate yet), both crews received a TCAS TA. Approx. 15 secs later, the 757 TCAS commanded a "descend,descend " RA while the TU-154 RA was "climb, climb". 1 sec after this RA Zurich AACC issued a "decend level 350, expedite descend" command, followed by a "expedite descend level 350" 14 seconds later (that's approx. 30 secs prior to collision, 15 secs after the initial TCAS RA).

Again, interesting questions arise....

There is yet another report from the German Air Traffic Control DFS on the same news page. This report states that at 21:33:24 UTC, 2min 9 sec before the planes collided, Short Term Conflict Alert got triggered on one of the radar screens of the Karlsruhe UAC of Rhine Radar. Both airplanes were visible on this radar screen prior to the STCA alert. 9 seconds later, until collision, the controller tried to contact Zurich ACC about this, but was unable to get through to him on the direct connection, even using the priority button. At times, the lines was busy, later the line was apparently available. The controller expected relief when one Mode C readout changed to lvl 361 but this was only temporary for one sweep.
Failing to get a connection on the direct line, he tried a call by conventional postal phone lines, but time ran out on this, unfortunately. Very sad, and probably a nightmare to watch the collision without being able to change fate.

E_o_D

[Low-Pass]

Agreed E_o_D, what a nightmare.

So it does seem that if ATC had known of the TCAS readings in the two aircraft, a conflicting instruction may not have been given.

Hmmmmm?

[Konkordski]

I wonder if that would have mattered -- surely TCAS takes priority, allowing pilots to disregard a contrary ATC call?

[Standard_Departure]

Here is the URL to the english version.

English report from BFU (http://www.bfu-web.de/aktuinfo-e28.htm)


This is so sad, there were even other ATC's watching it and they could not do anything.....

[RatherBeFlying]

My deep sympathies to the controller in Karlsruhe -- he saw it coming and was helpless to stop it because of the telephones and could no longer reach the Tu154 after it had changed frequency.:(

TCAS has acquited itself very well and as many have pointed out, by the time an RA has been issued, ATC must be ignored until the RA has been cleared.

There may be a cultural factor here as it seems Russians receive strong conditioning to follow authoritative directives no matter what -- here we see urgent ATC orders trumping a valid TCAS RA.

Perhaps Ruslan could comment.

Question: were the accident a/c on the same ATC frequency?

[Algy]

About VDL-4. There are epic amounts of information on this subject available: try http://www.nup.nu/ and www.gpc.se and www.avtech.se

Referring to it all as VDL-4 is misleading however. VDL-4 is just the datalink (the ICAO designation for what is otherwise called STDMA). There are other datalinks (Mode S or 1090, and UAT) which would arguably do just as well. That's quite an argument by the way - see the press cuttings on the above sites.

What you should call it is ADS-B (automatic dependent surveillance-broadcast), and the VDL-4-based version - as I think anyone who has been on the SAS flight demos will agree - is truly remarkable. It would make runway incursion-generated accidents a thing of the past (definitely would have saved the Linate and CDG runway collisions) and ditto mid-airs (but then TCAS should have saved this one of course.)

The US has just said that it is not intending to use VDL-4 as its ADS-B datalink - it's common knowledge that there are huge industrial base concerns playing a role in that decision. VDL-4/STDMA is essentially a Swedish concept, although, contrary to self-interested assertions from others, there are no patent issues restricting its use since its inventor, the admirable Hakan Lans, opened it up to everyone. It's also true that there are perfectly respectable technical arguments on both sides too (rather stronger on the VDL-4 side IMHO.)

Unfortunately, the industrial base issues are one of the reasons that ADS-B has been so long coming. But the real problem is to do with devising and implementing the operational procedures needed to make it work. Work it must be made to do, however - there is really no plan B, either in terms of safety or capacity.

[Standard_Departure]

RatherbeFlying:

I understand from previous BFU statements that they were on the same frequency.

Can you imagine being in the cruise, and then getting TA, RA and ATC(WITH URGENT COMMAND) in quick succession ? I don't know if simulators can generate the level of confusion/doubt that must have existed for the russian crew.

How would we (you/I) have reacted ? Very Sad indeed.

[Ghostflyer]

Low Pass,

As Koncordski says, it shouldn't have mattered. From various books:

Primary responsibility to avoid rests with the crews and ATC. Question ATC as early as possible about traffic which is a concern and coordinate.

If you have no SA on the traffic and get a TA and still can't see it then you are not well placed.

By the time TCAS is issueing an RA the time is for actions not words. ATC have had their go at providing collision avoidance and sadly missed the boat. On the ground you do not now have a sufficient update rate to provide sound real time guidance in the gravy strokes.

Now the automatic safety systems come into play which if followed sort the problem out. Quoting from the QRH for a bus:

Respond Promptly and smoothly to an RA
AP off
FD off
Adjust vertical speed to the green sector
Respect stall, GPWS or windshear warnings
Attempt to see the traffic
Notify ATC

What the book then says is:

Once an aircraft in compliance with an RA departs from its assigned ATC clearance the controoler ceases to be responsible for separation until 'Clear of Conflict' is called and the controller reclears the aircraft.

I await the report with interest but all of the data that is appearing seems to show that if the crews had followed the coordinated avoidance maneuvres as called by TCAS we would be talking about an Airmiss.

Ghost:(

[vertigo]

ferris,
Re your TCAS incident :
Congratulations for staying cool and getting your point across despite the readiness of others to shoot you down in flames.

I believe there was similar incident in UK airspace last week. Two Aircraft cleared to levels 1000' apart, entirely safe, yet TCAS decides the descending A/C should continue through the others level. The A/C didn't hit so it could be argued that TCAS did it's job, but surely the standard separation provided by ATC was infinitely safer ?

For every airprox TCAS causes there must be hundreds it stops, but we must all be aware of it's limitations and be willing to learn from others experiences as well as our own

[cockpitvisit]

One question... Wasn't the TCAS on the 757 supposed to change it's RA to "climb" after the Tupolev started descending instead of climbing?

[garp]

Ghost,
Do you still expect to receive an avoiding action call from the ATCO once you will get too close to an other a/c or do you simply expect traffic information? In your logic it seems that this is sufficient since the TCAS of both planes will take over anyway if things turn sour. Let's take the following example. Two a/c on parallel headings with 5 miles in between in IMC. One of the two is turned away from the other but actually turns towards it (really happened, the difference between left and right is not always well known). The only way to achieve separation again is to change levels. Do you expect us to climb or descend one or both, which can be contradicting TCAS or do you want us to tell the a/c that they are closing in rapidly and that they should just sort it out with their TCAS?
Garp

[atco-matic]

Vertigo, of the airmiss over Wales last week you said:

''The A/C didn't hit so it could be argued that TCAS did it's job''

Well I understand from colleagues that the E145 passed through the level of the Dash8 (FL180) just 1 and half miles in front travelling in the OPPOSITE DIRECTION so it was entirely luck- not TCAS- that prevented this incident. Without TCAS it wouldnt have happened as the aircraft were cleared to safe levels.:eek:

[Ghostflyer]

Vertigo,

Couldn't agree more, the same can be said of the historic picture from a search radar. It has its limitations and when the blips have merged the controller has a tough choice on what information to try and pass.

Interestingly though he will be working on exactly the same info as TCAS namely the Mode 'C' return but with the difference that his will be a sweep out of date whereas TCAS will be working in near real-time. Ferris' problem was caused by a pilot that didn't understand the limitations of TCAS, maneuvring his aircraft in-appropriately.

Ultimately if I were in the situation where I hadn't seen the aircraft approaching on TCAS and then couldn't see it out the window when an RA was activated. I am certain I would follow it. Just as if I was low on SA and a GPWS warning went off I would follow that.

Garp,

I would expect you to notice that the aircraft had turned the wrong way and tell him. If you couldn't get through give avoiding action to both aircraft to avoid TCAS even becoming an issue.

My general point is that TCAS gives a hint at 40 secs and action at about 25 secs. ATC's have the big picture from a long way away but unfortunately do not have the resolution except via Mode 'C' to separate aircraft at close range and that is exactly what TCAS is designed to do.

If you can hand on heart provide the best information to the crews, info that they do not already, then you are contributing SA and must chip in.

I know it is hindsight and when the controller first transmitted in this incident he must have been horrified. That said I would hope ATC SOPs at this late stage would be massively directive to both aircraft, DHL climb, Ruskie descend.

If transmitted just before the coordinated RAs it still might have not helped (life isn't fair) but at 44 secs to go, if just one aircraft had moved in the next 19 seconds it would hopefully have prevented any TCAS calls but at worst meant they didn't conflict with ATC's instructions when they came.

Ghost

[Low-Pass]

Ghostflyer and Konkordski,

I agree that a RA on TCAS should take priority over a controllers instruction. My point is that in this instance, the Tu did what the controller said which happened to be in conflict with TCAS. If the controller was aware of the TCAS warnigns, the accident probably wouldn't have happened unless the controller intentionally issued a cnflicting instruction. You can argue that it's the Tu pilots fault (and I don't) but that's only half the point. How can we avoid the same thing happening in the future? I understand that technology may not yet support this feature, but it will in the future.

[javelin]

I believe that part of the standard reaction to TCAS is that the PNF transmits TCAS Climb/Descent as appropriate and that should inform ATC that they are no longer the controlling body until the threat has passed.

[Ghostflyer]

Low-Pass,

Hopefully TCAS-5z will have that functionality. I think we are all agreeing here. It was a sh*tty chain of events. The Swiss collision avoidance system was down otherwise the conflict would have been spotted way earlier. The phones weren't working properly. Maybe ATC stepped on the RA descent call.

As to ATC getting automatic advice of the RA, yep good idea but playing devils advocate, lets say he was transmitting as that happened, the results could still have been the same. Lets face it once the RA has been issued the controller has a 50/50 chance of being right.

In the future when we are certain of the integrity of the system maybe at 30 secs to go ATC are taken out of the loop and TCAS is left to the job. But how would you know you had 30 secs to go? From the ATC collision avoidance system?...aaahh...but that was down. This accident may well be one that proves that life sucks!

Ghost :(

[sky9]

.Javelin

All very well, however we all know that you can only transmit when the frequency is clear. VHF radio is a pretty basic method of communication.
It is indeed a tragedy if TCAS actually worked and ATC unknowingly countermanded it.

[spekesoftly]

Beags,

You mention your SOP (1000/1000) when in RVSM airspace. Are you saying that this SOP does not apply below FL 290 ?

[BIK_116.80]

Garp,

The words “[callsign], TCAS climb [descent]” should be an air traffic controllers cue that a TCAS resolution advisory manoeuvre is taking place. On hearing that cue the controller should stop issuing vertical instructions.

An air traffic controller should continue to issue vertical and/or lateral instructions to converging traffic right up until they hear those words.

But once you hear those words, you have had your chance, and the time for issuing vertical instructions has passed.

The words “[callsign], TCAS climb [descent] complete, returning to FLxxx” should be an air traffic controllers cue that the aircraft has received a “clear of conflict” aural from TCAS and is now returning to the last cleared level. This is your cue that the TCAS vertical manoeuvring is over and you may once again issue vertical instructions.

TCAS “Crossings” and TCAS Training in General

If anything good is to come from this tragedy, perhaps it might be that hundreds of pilots and more than a few air traffic controllers have gone back to the books in an effort to more thoroughly understand TCAS and its related procedures.

I wish to express my gratitude to vanman who posted a very useful link to the Honeywell TCAS II Users Manual (http://www.honeywelltcas.com/pdffiles/tcas2guide.pdf) in a TCAS Requirements (http://www.pprune.org/forums/showthread.php?threadid=58499) thread on the Questions forum, and to Capt Pit Bull who has made a number of most informative and well written posts in regards to TCAS.

To both of you, a sincere thank you.

In particular, Capt Pit Bull has very eloquently described the TCAS “crossing RA” in the Nasty Incident (http://www.pprune.org/forums/showthread.php?threadid=58576) thread on the ATC Issues forum.

I must admit to having only had a very vague recollection of the term “crossing” in relation to the operation of TCAS. Prior to reading Capt Pit Bull’s post, I would not have been able to explain the significance of the word “crossing” in a TCAS aural. Obviously, there is no time to attempt to dig the coffee-stained manuals out from under the crew-meals when you are in receipt of a TCAS RA.

I was concerned that I might not have the knowledge I ought to, and I was further concerned that it was only me.

During the last week I conducted a very unscientific survey of five jet captains. Each one was separately asked “What does the ‘crossing’ part of a TCAS aural ‘climb crossing climb’ mean?”

They all said that they had never heard of the TCAS word ‘crossing’, and had no idea what it meant. That disturbed me even more.

There seems to be a real lack of understanding of TCAS by both pilots and air traffic controllers. This is evidenced, in part, by the reckless and/or misguided way that pilots continue to race up (or down) to cleared levels just 1,000 feet apart using unnecessarily high rates of climb (or descent).

From Capt Pit Bull’s posts, it seems that the only way you can generate a “crossing RA” is to use high rates of climb and/or descent close to your cleared level. Yet the apparently well-trained and experienced crews of a major flag carrier’s regional airline have managed to do just that! How can this be?

It seems that whilst regulatory authorities have mandated the installation of TCAS hardware, they have not ensured that crews receive adequate initial and recurrent TCAS training. The requirement to fit TCAS hardware only does half the job, leaving many pilots and air traffic controllers with an apparent distrust of TCAS due to misunderstandings brought about by poor training.

[Capt Pit Bull]

To answer Cockpit Visits question

TCAS continuously assesses the situation during an RA to see if a modification to the RA is required.

If TCAS sees, that inspite of the RA being flown, the intruder is still predicted to be within the vertical thresholds (i.e. the intruder must have manouevered towards you), then it will issue a revised RA.

This RA will take the form of either a strengthening of the original RA, or a reversal.

Strengthening:
"Climb" (1500 - 2000 fpm) becomes "Increase climb" (2500-3000 fpm).
"Descend" becomes "Increase Descent".

Reversal:
"Climb" becomes "Descend Now".
"Descend" becomes "Climb Now".

These manoeuvres should make it possible for the situation to be ressolved safely.

If you recieve one of these RAs, one of two things has happened:
a) the other aircraft has not got TCAS, and has for some reason unfortunately choosen a very bad time to manoeuvre in the same sense as you.
b) the other aircraft has got TCAS, and the crew have manouevered in the opposire sense to their RA (which, to reiterate, is strictly against training guidelines, and highly dangerous).

Based on what has been reported on the last page or so, it appears that the t154 did get a climb RA, and did manouevre opposite to it.

So, how come TCAS didn't save the day?

There are basically four possible scenarios.

Scenario 1.

We know the 757 left its level fractionally before the t154. We know it would have had a commanded vertical speed of -1500 to -2000 fpm. This would have put both its present altitude, and its predicted flight path, UNDER the t154.

One of TCASs design objectives is to avoid issueing RAs that will make the aircraft cross the intruders altitude. Rationale: Regardless of what happens horizontally, if the aircraft are never at the same level, they cannot hit one another.

Therefore, as TCAS saw the t154 start to descend, it probably would have selected a "strengthening" rather than a "Reversal", and given the b757 an "Increase descent". Simultaneously, the t154 would have been given an "Increase Climb".

Problem is, the t154 appear to have made the decision to follow ATCs avoiding action. It would seem reasonable that they would have initiated a descent well in excess of 1500 fpm and would therefore been matching the b757 as it steepened its descent.

What we are seeing here is the t154 manoevre opposite the sense of its RA not just once (descending instead of climbing), but twice (increasing its descent instead of commencing a climb).

In other words, TCAS would have been defeated by two manoeuvres opposite to given RAs.

Scenario 2.

As before for the initial RA, and opposit manoeuvre by the t154.

On receipt of the strengthened RA, and realising that they had heard the other aircraft say "TCAS Descent", the t154 crew followed their RA and climbed

Unfortunately, the b757 crew, having heard the t154 crew acknowledge their instruction to descend from ATC, decided to climb again. i.e. manoeuvred against the sense of their RA. The resulting levelling off / climbing, by both aircraft, lead to collision.

In other words, TCAS would have been defeated by two manoeuvres opposite to given RAs.


Scenario 3.

As before for initial RA, but this time TCAS choose the reversal scenario. (This might happen if the t154s manoeuvre was particularly sudden, such that it managed to 'out pitch' the b757 before TCAS reassessed i.a.w. scenario 1).

In this case, the b757 would have got a "Climb Now" RA, whilst the t154 would have got a "Descend Now" RA.

The b757, with their thus far proven track record of complying with RAs, followed the new instruction.

The t154 crew, having heard the b757s initial call of 'TCAS descent', and bearing in mind the "climb" RA they had been receiving, decided that they had better climb. Having (finally) made this decision, they were unable to change their minds yet again, and therefore initiated a climb inspite of the fact that during this manoeuvre TCAS told them to descend. i.e. a manouevre in the opposite sense to an RA.

Again, the resulting levelling off / climbing, by both aircraft, lead to collision.

In other words, TCAS would have been defeated by two manoeuvres opposite to given RAs.

Scenario 4

As per scenario 3, but this time the t154 crew respond correctly and comply with their RA.

The b757 crew, for some reason (perhaps the visual illusion I described in Tech Log), decided to increase their descent rate instead of climbing. Again, a manoeuvre opposite the sense of an RA.

Both aircraft increased their descent rates and collided.

In other words, TCAS would have been defeated by two manoeuvres opposite to given RAs.


(All Scenarios:

There may perhaps even have been a third round of RAs, but by this stage range was too close for anything to save the day.)


I trust my non too subtle post is reinforcing the point:

Don't manoeuvre opposite to an RA

Your Ops manual probably gives you the freedom not to follow an RA. Can I reiterate that it is one thing not to follow an RA, it is another thing altogether (and incredibly more dangerous) to manoeuvre Opposite.

However, even if somebody does, TCAS can still save the day as long as somebosy doesn't manoeuvre opposite the next round of RAs.

So, if something happens during an encounter that means you have to manoeuvre opposite an RA, or for whatever reason you suddenly realise that you have accidentally done so, whatever you do, follow the next one.

Historically, there are incidents where TCAS has saved the day at the second RA due to non compliance with the first.

There have also been incidents where 2 RAs have been manoeuvred opposite, and the only thing that saved the day was fortuitous lateral seperation.

CPB

[BEagle]

spekesoftly - the SOP is to avoid nuisance TCAS alerts in RVSM airspace only. Higher climb/descent rates may well be required elsewhere, particularly near (but outside) regulated airspace.

[fergineer]

So Beags, in reply to an earlier post that your ageing 4 jet has no TCAS fitted, does that mean that the Tri jet still does not have it fitted, the Comet like thing does not have it and the ageing prop fleet and maybe the newer prop fleet does not have it either means if i understand TCAS correctly means that you will not get the opposite command to me therefore the separation is going to be less in fact half, makes me feel an awful lot safer (not) when I hear the Ascot callsign, maybe its time that the Military were forced to update their fleets, I am here writting this because TCAS worked for me in Greek airsapce, the computor model that the CAA made from our tapes gave very little distance on a head to head. If it had been one of your Tri jets without TCAS I probably would not have been here writing this.
Food for thought at your next Flight Safety meeting eh!!!
Fly safely out there.

[Standard_Departure]

At the risk of losing the (patent) (copyright) benefits of something that is not out there yet.......

Does anyone know of a simple, PC based, program out there there that can simulate various TCAS situations.

I am not talking about MS Flight Sim or anything else that requires flying and navigating all over the place to get a single RA.

I am talking about training orientated TCAS situations, invloving various models of TCAS and multiple aircraft. Grading and post miss (or hit) commentary or evaluation could be in there too....

Anyone ???

[Capt Pit Bull]

BIK_116.80

Thank you for your kind words. However, just to clarify, high vertical rates near your cleared level are not the only way, just a way. Also a common way. Other scenarios possible, but involving ATC errors.


Beagle.

SOP versus Airmanship. It is not, I presume, SOP to intnetionally use high rates outside RVSM.


Fergineer.

Don't worry too much. TCAS manoeuvres you till its safety criteria are matched. If the other guy gets out of your way (i.e. coordinated TCAS) then you don't go so far from your original flight path, but get a certain separation (altitude dependant).

If the other aircraft doesn't manoeuvre, your corrective RA will last for longer before it slackens, but the size of the RA versus the time you have to manoeuvre means that you should still get the same ammount of seperation.

CPB

[Techman]

It appears that Capt Pit Bulls scenario 1 is close to what happened.

Press release from the BFU (http://www.bfu-web.de/aktuinfo-e28.htm)

[BEagle]

fergineer - the '10 doesn't have TCAS yet (but will do), the TriShaw is being fleet-fitted, the 130J and C-17 have it already. Don't know about the old 130K (but I doubt it) or the Comet 5.

Remember the guidance on 'state' aircraft and also that some Ar$ecoat call-signs will not have RVSM approval if operating in formation - for example on AAR trails.

I wouldn't be surprised to see EASA telling the military either to fit TCAS or to keep out of RVSM airspace altogether when they come into existence. I can see no reason (cost is no excuse) for such minority airpace users not to comply with normal regulatory mandates!

[Nightrider]

Captain Pit Bull, there is still one more scenario possible...something I don't want to think off, it shows that both TCAS systems ordered descent RAs....

It does not change the given facts.

What it did change, and I sincerely hope will do also in the future, is the fact, that plenty of us silently grabbed the (unfortunately too often too flimsy) ACAS documention available to us. Plenty of questions to ask and plenty of "new" findings while re-reading the basic principles of collision avoidance ideas.

Than there is the concerned thought about an aeroplane, equipped with the latest technology, and a crew who simply lacks the fundamental indepth knowledge about these systems and the associated procedures because there was no adequate training available or provided. Something which may be a factor in a lot of our beancounter run operations...

Let's face it, training is the best safety factor we can be provided with, a keypoint in our daily professional work. I for one hope, that this tragedy leads towards more questions and knowledge demands about the fitted systems in our aeroplanes.

[garp]

SD
The French administration DGAC has made a CD-rom called RITA (Replay Interface for TCAS Alerts) which is described in the following link http://www.sofreavia.com/pages/articles/pub_08.html
It contains about 16 different situations where TCAS is involved. Contact DGAC-CENA, Division SAS, 7 Avenue Belin, BP4005
31055 Toulouse Cedex France for a copy. It is purely designed for ACAS training of ATCO's containing the controllers view (including STCA etc), the pilot's view including IVSI with auditive alarms, transcripts of the RT and command keys to control or replay certain parts.

Capt PB,
If you receive traffic info about an a/c which is descending to a level above you with a high rate of descent and you have that traffic in sight will you still react to an RA? Concerning the reduced ROC/ROD when approaching a cleared level I would like to add that very often we NEED the a/c to make high ROD/ROC because of the traffic density. I wouldn't like to think of an environment where everybody is reluctant to give a good ROD/ROC when needed.

Bik & Ghost,
My point was that when you have traffic 5 NM apart and one of them makes a wrong turn you immediately lose your separation and you have about 40 secs before they would meet (considering they would travel 8 NM per minute) and hence have an RA at the same time that the ATCO can react.

Garp

[Semaphore Sam]

Very interesting, the implications of the above discussion. Assuming another generation of TCAS improvement, including lateral maneuvering & long-range forcasting, might the logic of this tragic incident lead to:

After having exited airport traffic zones (and other Very High Traffic Areas, TCA's etc, where very rapid situational changes can only be predicted by Tower and Approach/Departure Control personnel), aircraft might fly random (destination direct?) tracks AND flight levels, and let TCAS provide ALL ATC, so that conflicts such as recently occurred are resolved by one, AND ONLY ONE, authority? Granted, TCAS needs a lot of improvement, but the recent accident might lead to this conclusion (especially with potential long-range improved forecasting abilities of TCAS). Having flown for over 30 years trusting ATC implicitly, my very fibre rebels at the thought, but logically, it IS a big sky, and organized airways & Flight Levels just funnel aircraft into each other. Right offsets (another thread here) are an attempt to de-funnelize the sky; might random flight levels also help? Sounds weird, but logical.

[BIK_116.80]

Capt Pit Bull,

Yeah fair enough. I was attempting to portray the scenario where both aircraft were cleared by ATC to safe levels 1000 feet apart, as appears to have been the case in the recent UK regional airline event.

I understand that there are TWO ways to get a "crossing RA".

(1) High rates of climb and/or descent with no ATC screw up.

(2) Any rate of descent with an ATC screw up.

[Stupendous Man]

Just been on Sky News that the Tupelov was given a TCAS climb , just prior to the controller issuing a "Dive!" instruction.

Unfortunately for all involved it would seem he took the descent.

Now, as an ATCO, I am very interested as to what other pilots would do, given a situation of conflicting instructions like this......

[3forty]

stupendous man :
Pilots are trained to react to RA´s and follow it´s commands without delay.The system (Tcas) is very reliable and must have priority over ATC,in the same way GPWS does.
The tragic events of last week seem to confirm this idea.

[BEagle]

CPB - flexibility to use appropriate descent rates and high rates of climb outside RVSM airspace may be needed at times. TCAS is not an universal panacea - but I would hope that most crews would avoid extreme rates unless operationally essential.

[3forty]

As far as rates(climb/descent) are concerned pilots must follow the display on their verical speed indicators until "clear of conflict"sounds.I don´t think there is room for much flexibility when you have to deal with an RA !

[Capt Pit Bull]

Bik. My Bad. Misuderstood your previous.


Garp.

Ditto the RITA information. I looked at this package when putting our course together. Some of the events shown are classic 'how not to use TCAS' examples. Just a key observation though - the version I saw had examples where the TCAS version was 6.04, rather than the current 7.0 standard. This changes the presentation of some of the alerts, and also (critically) the logic with which TCAS deal with coordinating RAs.

As far as vertical speeds go, I'm sorry, but as far as I'm concerned, if you need me at greater than 1500 fpm within 1,000 of my level then something sounds like its on the verge of going wrong. I have no problem with high rates, its high rates close to cleared levels that cause this problem.

Personally, in the scenario you've given I'd follow the RA, and turn unless I could see a reasonable horizontal miss was happening. Its a no-brainer as far as I'm concerned, and should be for any pilot.

Let me make a general point to all readers.

If you fly a TCAS equipped aircraft, ask yourself this question:

"Have I, in calm consideration, on the safety of the ground, mentally prepared my self so that under no circumstances whatsoever will I ever intentionally manoeuvre opposite to an RA?"

If you can not truthfully, unequivocally, answer this question as "yes" then do the following:

Fly with your TCAS in TA only mode.

That way the rest of us can get out of your way, without TCAS to TCAS coordination reducing our escape options.


Back to Garp

If you tell me to expedite, I'll do so. But in my experience, you don't get cleared to a level and told to expedite to it - its always expedite through a level. E.G. Descend FL80 expedite through FL100.

If you told me to expedite all the way to a specific level, I'd still do it. BUT I'd be prearmed to avoid 1,000 foot level off RAs. So lets say I'm at FL95 descending FL80, at 3000 fpm (at which point the it would be nearly time to start levelling off anyway with that ROD). I'd look at the TD for traffic at -25 (i.e. FL70). If I got TRAFFIC TRAFFIC on that blip I'd already know I'd be looking at a likely RA in 15 seconds if I don't reduce ROD, so I would do.


Nightrider

Well, I never like to say impossible, but knowing how the data link works it just isn't going to happen. If the system were capable of such an error, given that thousands of real RAs have occured, it would have happened before...

The rest of your post however is spot on. My TCAS training program was nearly still born - had to fight hard to get a half day in the classroom - I feel like a lone voice in the wilderness sometimes....

CPB

[Nightrider]

Well...it looks like that Capt Pit Bull comes close to what has happened....and now the question is, did the Russian Crew know how to react to a TCAS RA.....

And the rest of us needs to follow the words just typed a couple of minutes before...

"Have I, in calm consideration, on the safety of the ground, mentally prepared my self so that under no circumstances whatsoever will I ever intentionally manoeuvre opposite to an RA?"

Training...when will we ever understand that training is the only way to acchieve what we want? And than...who is going to convince the beancounters?

[RatherBeFlying]

According to my local paper in Russian pilot given contradictory orders (http://www.thestar.ca/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1&c=Article&cid=1025795660481&call_page=TS_News&call_pageid=968332188492&call_pagepath=News/News&col=968793972154)
Russian aviation officials said the pilot correctly gave precedence to the control tower before the July 1 crash, but western aviation experts said pilots are trained to give precedence to the cockpit warning.
So who are the "Russian aviation officials"?

With the help of Altavista web page translation, I dug around www.izvestia.ru and found this article: They attempted to warn dispatchers 7.7.2002, 16:33 It begins with the Karlsruhe controller trying to contact ZRH, discusses the climb RA received by the Tu-154 and concludes with :
However, obviously, the command of air-traffic controller for the pilots is priority.

[ww1]

TCAS said "up", controller said "down", and the pilots followed the controller? True? If so, is this normal procedure for Russian crews?

[purr]

in case of a RA it may not be a good idea to climb and turn unless the software caters for it (not yet in the market) on thrust limited
aircraft you may run out of vertical speed. :D

[NigelOnDraft]

Re "high RoD / RoC"

I think it is for ATC and TCAS reasons that in the USA, rates expected by ATC are specified. Don't have it to hand, but something like >1000fpm until 1000 to go, then average of 500fpm.

My experience of TCAS TAs / RAs is that high performance twins in the climb are usually the problem, and more and more crews are using VS in busy areas to reduce the RoC - as we leave LHR in the morning on an "early" departure in a 757E4, its a but unfair on those arriving LH crews from the USA who have been awake all night, to keep pinging off their TCAS!

Re this incident, I would be interested to know the relative volumes, to the pilot, of the ATC instruction v TCAS. I personally have experienced a GPWS "pull up" leaving ZRH that was almost inaudible due ATC chatter and noise reducing headsets. It might not be as simple as the crew clearly understanding the 2 instructions, and having to decide between them...

Finally, for those saying "TCAS RA overrides ATC" - bear in mind that is your (and my) company's / state's SOP / rule. Has anyone established that for the Russian crew this is so?

NoD

[Standard_Departure]

Pilots....

What are your thoughts on TCAS auto-coupling to Auto-pilot ?

So that the Autopilot will follow the TCAS (GPWS/Wind Shear) RA, giving the pilot time to try and establish visual contact with the intruder and voice contact with ATC?

[Few Cloudy]

Stupendous man was right - Source here is the NZZ newspaper in Zuerich today:

According CVR analysis the Tupolev pilot got a Climb RA just about one minute before the crash - one second later the controller told him to descend 1000ft and expedite. His level was expected to be lower for the remainder of the flight to Spain by the way, so the controller chose him, rather than the Boeing, for descent.

Soon after this the controller again ordered the descent - in the meantime the Boeing pilot, following TCAS RA started his descent and correctly called his action.

The reporter thinks that the controller presumed that the Tupolev was holding altitude and so accepted the Boeing descent. Unfortunately the Tupolev, following a short period of indecision decided to follow the ATC command and descended too, with the disasterous results known.

We are here to learn, not to apportion blame and what we can all learn is that TCAS works but that it MUST be followed unquestioningly. This, as has been pointed out, is in most company SOPs. Spare a thought for the Tupolev crew, however, who had already received the TA (Traffic) and were in the picture, got the RA (Climb) and immediately an order to descend expeditiously. This situation should become a simulator 'must' for the future.

[Capt Pit Bull]

Purr,

Good point. In my earlier posts I haven't covered all the guidance I give to crew, but one point is that the RA is the priority but if performance limiting then sacrifice the turn rather than the RA.

There are counter arguements though - if you are having trouble climbing, anything is better than nothing. Even no climb is still likely to be safe - because if you've got climb, the other a/c has got descent, so it won't have a performance issue. I.E. TCAS alerting itmes and threasholds are designed around one aircraft getting out the way of another that doesn't manoeuvre. If the other guy is alaso TCAS and helps get out of the way, thats a bonus.

As a supplementary point, TCAS performance inhibitions are only approximate anyway, it can't possibly be aware of all the variables, so crew always need to protect the flight envelope manually.

Finally, most RAs only involve changing your flight path by a few hundred feet. Even in the top altitude band, TCAS only tries to generate a 700 foot miss. So, thats 350 by you, 350 by the other a/c. As such it doesn't even need to be a sustainable climb. Go to MCT or Take off thrust - even a little increase in thrust (given that ROC is based on Excess power) can make quite a differerence Flying a low performing Turboprop? Back at minimum speed struggling up at 500fpm and receive a climb RA? Pop out a stage of flap, then zoom climb back to that minimum speed - that'll give you a few hundred feet which will be enough.

NigelOnDraft.

Using VS mode on departure. - Great Idea, Great Airmanship. In my quadrapuff its quite perverse that on most sids you get cleaned up and accelerated to 250 often just as you reach a thousand or so to go to the first block level. Till then you get maybe 800 fpm. From then on, all the excess power now goes to ROC and left to its own devices the a/c will hit 3,000 fpm or more easily. Intervention from Level Change to Vert Speed is highly sensible.


Standard_Departure

Because of the timescales involved, responses to RAs must be prompt - particularly updated RAs. Most A/Ps just aren't capable of reacting fast enough. Certainly, my a/c wouldn't have a chance without a major a/p revision, at which point you'd be into design compromises with what ever factors made the engineers design it the way it is at the moment.

This, combined with the need to make sure that an autopilot mode change doesn't inadvertantly cause a manoeuvre opposite to an RA, is why A/P must be out for ALL RAs - not just correctives.

CPB

[Standard_Departure]

Capt Pitt Bull;

Thanks for the response, that makes sense.

Few Cloudy;

When I read The reporter thinks that the controller presumed

I just go to the next article. Not getting at what you posted, I am talking about the reporter...


SID

[Proceed As Cleared]

The Russian sources' claim that ATC clearance has to be given priority to TCAS RA is utter bollocks !

Looks to me like someone's desperately trying to blame the controller only...

:mad:

[PFD]

States:

Action on receiving an RA (Resolution Advisory)

Pilots are to initiate the required to manoeuvre immediately, adjusting flight path, aircraft power and trim accordingly. Crew members not involved in executing this manoeuvre should confirm that the sky ahead is clear of other aircraft and continue the visual search for the established threat. They are to inform ATC asap of any deviation from an ATC clearance.

and

If pilots receive simultaneously an instruction to manoeuvre from ATC and an RA, and both conflict, the advice given by TCAS should be followed.

This is what I teach and shall continue to do so, because,

I WANT YOU TO LIVE.

Regards

[PFD]

I just spotted this in Ghostflyers post,

When you get an RA, you are 20 to 30 seconds from collision.

You should have already had a TA ('Traffic,Traffic') which is 35 to 45 seconds from possible collision.

Mode C and S transponders will also give you height information.

Displayed as the difference in hundreds of feet between you and the target, it also says + or - so you know if it's above or below.

If you both have Mode S the RA manoeuvre will be co-ordinated.

If the other aircraft has a transponder but no TCAS, yours still works.

regards

[vanman]

A typical TCAS II maneuver requires crew response to the initial RA within 5 seconds and G-forces of ± .25 G.This force is similar to that experienced when initiating an enroute climb or descent. Because of this G-force requirement, the response to the RA cannot be flown using the autopilot. The autopilot must be disconnected prior to responding to the RA.When the initial RA
is changed,the crew must respond within 2 1/2 seconds.
In the latter case:-
You are expected to initiate the change from <one maneuver> to <the opposite> maneuver within 2.5 seconds
using an acceleration of .35 Gs.

Source: www.honeywelltcas.com/pdffiles/tcas2guide.pdf

Don't quite see what they mean about the G-force being the same as that required to initiate an enroute climb or descent as obviously we normally initiate those through the autopilot, but anyway the timeframes for response (and increased G requirement for RA reversal) are worthy of note eh?

Cheers

[Ruslan]

Okay,
I'm just seeing repeatedly declaration (however should agree here) that we should follow RA even ATC saying others. But all of you refer to equipment manuals company rules etc, have you heard that no any legal regulations in that matter published in Russia (Russia not participate in RVSM neither any RVSM buffer area), from my understanding pilot should have some training to got RVSM able status operating within RVSM areas that is only a case that could got any training in part of TCAS procedures (I’m even not thinking about sim)…

Please do not consider guys working on western types and got excessive training before somewhere in Miami, furthermore on types which have TCAS onboard installed by default from manufacturer as standard equipment.

[EGGW]

Bottom line, obey TCAS commands when it comes to an RA. The crew of the Russian aircraft had a VERY confusing situation, and made the wrong choice.
My view at the moment, the Swiss controllers gave much too late instructions to descend. Why they chose to carry out maintenance of the STCA, and the procedures to account for that being U/S, seem rather inadequate right now. Why there was only one controller also on duty begs a question.

As you can see there is really no one single person/company to blame, a chain of errors. http://www.smilies.nl/crying2.gif

[Standard_Departure]

Is it fair to say that there will be a "cause of accident" which may be a chain of events (albeit all within the skyguide "system")?

Furthermore, can it be said that if the pilot of the 54 had made a different call the accident could have been avoided (Note no blame)?

SID

[Nightrider]

At this stage, with all the available facts made public by now, I am almost inclined to see a very very sad problem here. The russian crew had all the equipment, and it also appears that this equipment worked as expected, and they simply failed to have the knowledge about this system.
Being in a position to listen and follow orders, they did as they use to do for as ling as they worked as an aircrew. The "intrusive" call of the TCAS created some confusion but was superseeded (in their views) by the ATC call to start decent!

It is not enough to have a little knowledge....

[Stupendous Man]

Re:TCAS vs ATC instructions


I know that if a pilot is supposed to inform ATC of any deviation from flightpath due TCAS RA, should it now be the situation where we are informed BEFORE this takes place and therefore should the TCAS parameters be changed to allow for more time.

I know that this could potentially end up with more TCAS related climbs/decents - but is this preferable to the tragic events of last week.

[mole]

Stupendous,

Surely the point is that ATC are supposed to stop it happening. If this fails then TCAS must be followed to solve the problem. In this incident the accident would not have occured if:

ATC had moved the tracks away from a collision path.

and when that didn't happen:

TCAS RA's had been followed.

Unfortunately neither occured so the worst possible result happened. The question is why.

TCAS is RIGHT - when it wakes up it is because something else has gone wrong. This can be as simple as inappropriate vertical speed or a total breakdown of separation. Whenever TCAS gives guidance we must follow it, even if that means we ignore ATC.

[garp]

The Russian crew decided to trust the instruction given by a human rather than the one given by a machine. Even if with hindsight they shouldn't have done it they just did what probably thousands of other pilots would have done. Those seconds when all three of them were looking at each other what to do must have been terrible. I also would like to add that in my experience the Eastern European pilots in general have a high level of profesionalism and frequency discipline. Something that can not always be said of the other European crews.

Garp

[Avman]

I'm not the technical type (leave that to the wife), but wouldn't it be fairly easy for TCAS to "talk" to the transponder, triggering a warning to ATC that the a/c is following an RA?

[unwiseowl]

Don't blame the 154 crew. Don't blame that poor controller. The blame lies with Skyguide management.

[Standard_Departure]

Avman,

I asked a question like that earlier in the thread, the simple reply is that there would be a requirement for mode-s (or in the future ADS-B).

It is obvious (and this accident is proof thereof) that ATC needs to know immediately when the TCAS commands an RA. It is also obvious that we cannot expect pilots to think about comms in an RA environment, there are just too many "more important" things happening during those moments.

There are 2 possible solutions;

The first is aircraft based, As soon as the TCAS commands an RA, it can (could) command the Transponder to automatically squawk a specific code (7400 ?) which would then indicate to the ATC that that specific aircraft is under RA navigation.

The second is based in the ATC Radar Software (maybe even as a function of STCA). The parameters used by TCAS (for RA) could be incorperated into the ATC software, so that when the RA would be commanded in the cockpit, and indication on the Radar display would show that there is a (potential) RA and indicate which 2 aircraft are involved. Bear in mind, this is simply 2 different computers that are using the same data, manipulated by the same parameters.

In addition to the above (whichever way it goes), the ATC would be mandated to take no (vertical) action until the "clear of conflict" call is made.

To repeat, It is painfully obvious that ATC needs to know when they have reached the end of their "jurisdiction", and pilot's can not be expected treat comms with any priority when they are possibly playing their last hand.

SID

[Stupendous Man]

Mole - I agree with what you say, and the situation should not have occured in the first place. however it unfortunately did.
But does the current TCAS system allow enough time for a controller (or pilots) to react to potne=tially conflicting advice.

We all know what pilots are supposed to do with an RA - follow instructions and tell ATC - but had any one considered the possibility of last weeks events happening? I think most peoples insticts (in any given situation) are to follow the human input rather than a similatneous computer one. Human nature. Especially if the human voice has an element of urgency or panic - which I am sure was the case in this instance.

[RaRadar]

Avman, Standard Departure

It is aready a feature of the Mode S transponder to initate a downlink message that contains the RA. The new Mode S radars that are starting to be installed in Europe will be able to extract this information. However, due to the radar update rate the delay will be between 0.25s and 10s.
Before this information can be presented to the controller the radar data format to the ATCC will need to be upgraded as will the display system. The move by Eurocontrol to impliment Mode S Enhanced Surveillance should make this happen.

RR

[Shagtastic]

A TCAS command surely has absolute priority over a conflicting ATC instruction because even the ATC instruction could be a malicious transmission from some neandathol with an expensive toy.

So sadly who is too guarantee the validity of what you hear over the radio.

[Avman]

SID & RaRad

Thanks for your comments and info. Certainly any delay over 1s would be too long and would defeat the objective. Mode S is a wonderful box of tricks. Unfortunately I guess that upgrading and susequent full implementation is probably still some time away for many ATC units.

[Blacksheep]

Just a word from an avionics engineer so don't get mad if this is impractical.

TCAS provides a Traffic Advisory (TA) to the crew when it detects a possible conflict. The crew are thus made aware of the conflict some time before a Resolution Advisory (RA) is issued and can locate the threat aircraft on their display. Both crews in this accident would have been aware of the conflict for some time. Might it not be good idea to have crews report Traffic Advisories to ATC whenever they occur? I don't know how often they occur , so maybe in practice, it would cause chaos to have every TA reported. Nevertheless, in this accident, if either or both crews had informed ATC of the conflict when their TCAS systems issued a TA, the controller would have had his attention directed back to the priority area in time to take appropriate action. A Resolution Advisory is meant to be a "Last Chance" warning. Although the TCAS design intent was for Traffic Advisories to give crews time to avoid the need for Resolution Advisories, in practice it isn't always possible for crews to visually acquire the threat aircraft.

Maybe it is now time to include ATC in the warning loop, but I suggest they be brought in at the beginning when a Traffic Advisory occurs, rather than wait for the Resolution Advisory to be issued. Its too late then - once an RA is issued, effective Air Traffic Control has already failed.

**************************
Through difficulties to the cinema

[Feather #3]

Even better, Blacksheep, if I see a '00' with an open diamond heading for me, I ask! It helps.

G'day :)