Mid-Air Collision over Southern Germany (merged) [Archive]

Capt Pit Bull

2nd Jul 2002, 07:47

Flying Bean,

TCAS alerting is based on prediction of a 'Closest Point Of Approach' (or CPA).

If the predicted CPA is too small (horizontal and vertical values depend on Altitude - the higher you are the bigger the predicted 'miss' must be for TCAS to consider it safe) then a Resolution Advisory (RA) will be generated once the aircraft are within the RA Alerting Time.

This value also varies with altitude, from (if I recall correctly - manual not to hand) some 15 seconds at low levels to 35 seconds at high level.

The RA is preceded by a Traffic Advisory, 10 - 15 seconds earlier, depending on altitude.

Since it is a time parameter, the particular point you've raised, about a 'nose to nose conflict in fast jetliners' is not an issue.

i.e. the greater the rate of closure, the greater the distance at which the alerts are generated.

However, the increased time allocated to Alerts at high level does not translate into more time for 'assessment and reaction'. The reason more time is given is because:

a) Altimeter inaccuracies mean that a bigger vertical miss must be provided by TCAS to be sure of safety. I.E. aircraft could be at the same level even though in reported altitude terms they lcould look like they are a couple of hundred feet apart. Hence the safe separation required is effectively:

Worst Case scenario of altimeter innacuracy, X 2, + required actual separation.

b) High altitude make the aircraft less manoueverable (IAS / TAS relationship).

The alerting times are selected so that the aircraft has enough time to go from predicted co-altitude with intruder to safe separation, plus 5 seconds of reaction time for the crew.

As a final point, there are various eventualities that can delay or even prevent the TCAS response. However to go into them here would be verging on speculation.

If you require more information on TCAS function, I suggest a search on Tech Log.

CPB
(former) TCAS instructor.

Flame Out

2nd Jul 2002, 07:49

Typically, there are two kinds of TCAS advisories, TA - Traffic Advisory and RA - Resolution Advisory.

Traffic advisory TA, is activated when another aircraft is about to intrude the TA protective envelope within approximately 40 sec. The envelope is 0.75 nm radius and 850 ft above and below your a/c. The TA will provide both visual and aural cues, ie the display will turn the color of the traffic from white to amber with the aural warning, i.e "Traffic, Traffic"

The Resolution advisory RA, is activated when another a/c is about to intrude the RA protective area within approximately 20 sec. The RA protective envelope is 0.30 nm and 600 ft above and below your a/c. The color of the symbol will now turn red and the aural warning and the maneuvering command will be displayed on the VSI with the aural warning, i.e "Climb, Climb Now!" "Climb, Climb Now!" Compliance with the commanded maneuver is required with 5 sec (2.5 for enhanced RA) of the aural warning with at least +/- 0.25 G maneuver.

"Clear of Conflict" will be announced once the traffic is well cleared.

There is a new version of TCAS called TCAS VII that is not widely used or required but it provides both vertical and lateral RA.

Note: TCAS will not be able to detect a/c that do not have operating transponder. They will not provide RA against non-altitude reporting transponder. It has automatic function to make coordination with the other TCAS equipped a/c in case of RA so both a/c's will not move in the same direction.

What I described above is how a TCAS II would operate and I believed that the B-757 is probably is equipped with such a system. No idea what was on the Tupolev, if any...

Condolences to all that perished.

Avman

2nd Jul 2002, 07:57

Actually, it was A9C-DHL, c/n 24635 - on flight DHX611.

All DHL flights are regular customers in our airspace and we extend our sincere condolences to the staff and families of EAT/DHL, not forgetting of course the tragic loss of young lives on the Tu-154.

eratic

2nd Jul 2002, 08:19

some recent pics of the DHL aircraft on the ramp at BAH
they're a bit dark (tinted windows) and there's some nasty camera reflection

http://www.dhl.com.bh/images/bah/115-1575_IMG.JPG
http://www.dhl.com.bh/images/bah/115-1576_IMG.JPG
http://www.dhl.com.bh/images/bah/102-0235_IMG.JPG

Electric Sky

2nd Jul 2002, 08:39

Devastating .... condolences to all involved.

Is the aircraft anything to do with EAT? Isn't there a Bahrain based DHL franchise?

Here are pictures of both aircraft involved:

http://www.airliners.net/open.file/062723/M/
http://www.airliners.net/open.file/183748/M/

ES :(

320DRIVER

2nd Jul 2002, 09:06

From what I can gather from these posts the DHL pilot was responding correctly to TCAS RA to fly down. Now if the TU154 was in RVSM I shouldn't it have TCAS installed as a requirement?; so shouldn't the two TCAS computers co-ordinate the avoidance action?

In any case, it is an accident which should have us all reflect that even in one of the best controlled airspaces with all the modern airborne equipment etc. we still need to be scanning that sky or at least scanning the ND continously for suspect TCAS targets in order to have as early a warning as possible of potential threats.

Another thing which I hope will *not* happen after this accident is that pilots will become wary of following TCAS RAs if it transpires that the DHL pilot still got himself into trouble by following the TCAS instruction. We could end up in the same trap where pilots "analyse" GPWS warnings during an approach.

I did have a TCAS RA once during cruise (FL350, European airspace) and since it was an opposite (uncontrolled!) fast military traffic, our TCAS didn't have time to give a "TRAFFIC, TRAFFIC" warning and we were issued with the "DESCEND, DESCEND" warning immediately, accompanied by the controller "screaming" a lateral avoidance vector at the same time.

Condolences to all involved and please also think about that poor ATCO and what he/she must be going through. :-(

Fraudsquads

2nd Jul 2002, 09:07

My initial thoughts here were (as reported as a possibility on Sky News) that the crew of the Tu154 had changed frequency before the warnings came from the German ATC. Did the Tu154 crew respond visually to the 757?

The warnings I assume came once the flightplan of the 757 had been handed forward from Swiss control. Please correct and forgive me if this is an unlikely cause.

Deepest sympathy to all those close to the unfortunate vicitms of this crash.

FS

moggie

2nd Jul 2002, 09:11

1) Does a Russian built transponder give altitude/flight level information that a western built TCAS can use?

2) Why did the "authorities" tell us of large numbers of casulaties on the ground when no-.one was even hurt, let alone killled?

A300Man

2nd Jul 2002, 09:21

Sincere condolences to all those involved with and affected by this tragedy.

Lets hope that there is no witch-hunt by the media and the authorities, but rather a full, accurate and worthwhile learning experience to all of us involved in the industry.

Let the next lesson be a less costly one.

HercBird

2nd Jul 2002, 09:32

Condolences to all involved. Totally tragic. :( :(

From the news it appears that the Russian plane started the descent at the same time the DHL plane was descending due to TCAS. I am reserved in saying this as my only source is the media (not the most accurate in accident reports)...

Can someone confirm this ?

A few other questions, excuse the ignorance. I am not trying to second-guess the ATCs involved in this but, could they have not given the DHL a higher flight-level after the first couple of calls to the Russian plane ? What are the limitations of even a fully loaded 757 concerning max FL ? Or would it have just taken too long ? What about a turn ?

Also a couple of questions concerning procedures. Usually how long before a handover is the second ATC alerted ? Is it usual practice for an ATC to request from the previous ATC to give the plane an instruction before it is handed over ?

Again, excuse my ignorance, and I am not second guessing people, just questions that came up in my mind after having heard of this...

Guy D'ageradar

2nd Jul 2002, 09:37

Contrary to various statements here, I have seen great improvements in the quality of Russian pilots over the last 4 or 5 years. In fact, I would have more confidence in a positive response to avoiding action from certain Russian airlines than from the sub continental airlines and/or some of the big Europeans who tend to reply with "was that meant for me?"!!!

The reluctance of some pilots to appropriately respond to avioding action has already been discussed at length here (http://www.pprune.org/forums/showthread.php?s=&threadid=55644)
- I wonder if this will make some of you think differently about your response in future.

This is not meant to antagonize / inflame the discussion but the link should be obvious.

Condolences to all involved and my colleague in Zurich.
:(

Confirmed Must Ride

2nd Jul 2002, 09:41

Sorry not too hot on TCAS as feet normally rooted in the holds. Why does TCAS make you go down instead of turning left/right to avoid other aircraft?

Ghostflyer

2nd Jul 2002, 09:41

Condolences to all involved.

Stating the obvious, clearly, the 2 aircraft were flying at the same altitude without lateral seperation. Isn't it about time we took steps to ensure both lateral and vertical deconfliction outside of terminal airspace.

With modern GPS equipped aircraft every time we go flying we go either directly over or under other traffic; the big sky principle no longer applies.

Last time I checked, airways were 10 nm wide, why don't regulators require all operators to offset 1 mile right (or even 100m) in the cruise phase to reduce the chances of this unfortunate accident re-occuring. Even in RVSM airspace, there is sufficient space to allow this principle to be applied until the aircraft begins descent.

It might appear that I am trying to bolt the stable door after the horse has bolted but how many of you guys out there have had the same thought when you have had a min-sep 1000' below another aircraft with 16 miles/ minute of closure.

Again condolences to the families,

Ghost:(

Ghostflyer

2nd Jul 2002, 09:43

CMR,

Because TCAS uses Mode 'c' to arrange deconfliction. At the moment it does not have sufficently good lateral resolution to ensure avoidance.

Ghost

Alpha Leader

2nd Jul 2002, 10:07

Today’s mid-air collision over Southern Germany is, according to Skyguide (the Swiss ATC), the result of simultaneously initiated descents by both the aircraft that eventually collided. In the case of the Russian Tupolev TU-154, the descent was initiated based on ATC instructions, whereas the descent of the B-757 freighter was triggered by its TCAS.

Anton Maag, Chief of Zurich-Kloten Control Tower, and Skyguide Spokesman Patrick Herr, held a press conference today, Tuesday, to review the events of the previous night.

Between 2300 and 2400, there were no unusual occurences in Swiss air control space, with only a few aircraft in the air. Swiss ATC was handed over the Russian TU-154, which was on a East-to-West routing by German ATC at around 2330, whilst the B-757 freighter, on a South-to-North routing, was handed over by Italian ATC to Swiss ATC at 2323. Both planes were at an altitude of 36000 feet (around 11500 meters).

The Swiss controller thus advised the Russian aircraft to descend to a lower flight level. According to Skyguide’s Anton Maag, it required three attempts before this advice was confirmed by the Russian crew. As a result, the Russian aircraft began its descent very late. At the same time, the crew of the B-757 freighter was advised for reasons unclear by its TCAS to descend as well. Obviously, according to Maag, this command has to be followed immediately.

The eventual collison happened at an altitude of 35000 feet between 2335 and 2336. Both aircraft remained visible for a number of sweeps on the radar screen. Maag says there were no linguistic problems between the Swiss controller and the Russian crew, whilst Herr mentioned two “sticking points” in the context of this crash. “First, why did the Russian pilot not react immediately? Second, why did the TCAS on board the B-757 advise its crew to dive?” So apart from the question as to why the TCAS on board the B-757 did not recognize the other aircraft's descent, both aircraft were tuned to the same radio frequency, so they could both simultaneously hear their respective interaction with Zurich-Kloten tower.

Above compiled based on Swiss media reports available online.

Capt H Peacock

2nd Jul 2002, 10:07

This is indeed a tragic accident, and but for the grace of God could have taken many, many more lives. I don’t presume to make any conclusions about this event, but there are a number of issues that we should think about in busy European RVSM airspace.

Respond to TCAS resolution advisories in the extent to which the cues are provided on your EADI or EVSI. An RA will often require no more than 1500 fpm climb or descent to deconflict the traffic. At high Mach numbers and flown manually, the pitch change is remarkably small. A panic large input may cause additional problems or even an upset.
Resist the temptation, especially at night, to try and second guess the TCAS RA. In RVSM, and aircraft 1000 feet below you might look as if it’s actually above and vice versa. Trust the TCAS and use it to enhance your mental model of your bit of airspace. You may think you’ve worked out the best avoidance, but the TCAS has a contract with the conflicting traffic and has worked out the best avoidance manoeuvre. Remember, the other target may be simultaneously involved in avoiding another aircraft.
If your aircraft is fitted with an early type of display, remember that the azimuthal error in TCAS can be up to 20, which means that the intruder could be either left of the nose or right of the nose. TCAS is designed to provide only vertical deconfliction, so again don’t try to second guess it.
Listen out on your frequency, try and plot other aircraft in your mental model, and think about where conflicts might arise. If necessary inform ATC of any concerns you have about another aircraft. They will be more than happy to put your mind at rest.
Make sure that at least one of you is monitoring 121.5 at all times. Someone may have urgent news for you, and you may not be talking to them at the time

It is entirely possible that at least one of the aircraft involved in this did all of these things. It is tragic in the extreme. I offer these pointers not to criticise or suggest possible cause, but to reinforce good airmanship and operating practice.

Sincere condolences, and my deepest sympathy to the controller at Swiss.:(

purr

2nd Jul 2002, 10:41

sincere condolences to the families

Were the pilots english speaking.If they were not it is possible that the translator for some reason was not in the flight deck when the atc called.
Just thinking aloud.

Fox3snapshot

2nd Jul 2002, 10:45

Dealing with numerous Russion/Ukraine registered and operated aircraft here on a daily basis from An-12's right up to the big daddy An225 and every variety of Tupalov, Yak and Ilyushian, I can honostly say the aircrew are some of the most courteous and accomodating pilots we work with, far more so than quite a few of the western/sub continent/Asian and local operaters we deal with. The english and general operations have improved dramatically over the last few years. I will be the first to admit that it is important that sometimes extra effort is required to ensure the correct information has been absorbed but then this does not just apply to them.

It is far to early to make any reasonable conclusion on what has happened here and it is important to realize how many variables are to be addressed, including Comms, ATC Handover/Takeover procedures, ambiguous ATC instructions and mis-understandings, there is even possibility of an in-flight situation on the Tupalov that inhibited an immediate response.....and the list can go on.

Additionally my fear is that amongst Aircrew and ATC alike, to much emphasis and reliance is being placed on the TCAS system and on a daily basis the call "its OK I have him on TCAS" or more so the fact that pilots are trying to separate themselves or continually harass ATC about TCAS traffic that is under ATC control (especially on the climb or descent), is causing many a misunderstanding and unnessary RTF clutter.

Let all the facts be gathered, make no more speculation based on the typically innacurate and sensationalized media reporting and all will be revealed.

Regardless of who is at fault, there have been peoples lives destroyed, families destroyed and life long reputations to consider. Lets just show compassion at his stage and let the authorities sort the facts out. This is a trajedy for all of the world's aviatian community.

:( :( :( :( :( :( :(

atc_ring

2nd Jul 2002, 10:48

Thank you Alpha leader for keeping us posted on the latest info on this tragic event...
Without trying to draw any premature conclusions, it seems to me the Skyguide Spokesman, Patrick Herr is correctly focusing ATC investigation line on those two "sticky points".

R.I.P. for the innocent Souls on board....

Guy D'ageradar

2nd Jul 2002, 11:18

Fox3snapshot,

My sentiments exactly. As I said earlier, Russian R/T has improved dramatically over the last 4 or 5 years. The obvious questions now seem to be - 1. was avoiding action given 2. If not, why not 3. If yes, why was a collision not avoided? I don't want to pre-empt the investigation but these questions need to be answered.

Again, Condolences to all.

captchunder

2nd Jul 2002, 11:24

Anyone had a TCAS RA "reversal"; ie "Descend, Descend" turn into "Climb, Climb now!"? I've had it in training but not on the line (fortunately).

Again, all is speculation at the moment. All we can do right now is feel symapthy for all those involved.

atc_ring

2nd Jul 2002, 11:31

yes, Guy these questions pop up to mind but other factors should be also under consideration:
1. how busy was the sector?
2. R/T freq. congestion (or condition)
3. russian pilot's english level
...these are (inter alia) some questions that pop up in mind....
Answers should be very carefully joined together so that correct conclusions are drawn and put to prastice ASAP to avoid similar situations in future (here I speak as a front line radar ATCO)...

Fox3snapshot

2nd Jul 2002, 11:32

If (a big if!) it is the case that the DHL aicraft initiated descent in response to the TCAS information (and possible ATC traffic info) and the Tupolov after eventually receiving his descent instructions (Swiss controllers apparantly gave 3 calls) commenced his descent, the concern I have for TCAS confusiuon mentioned previously has been realized. Latest reports (from a Swiss ATC source) also inidicate that the aircrew on the Tupolov were having no problems understanding or speaking english.

:confused: :confused:

WhaleOilBeefHooked

2nd Jul 2002, 11:39

NilNoted

Yes it was the Australian registered B757, not an English registered one. A9C DHL formerly OODLK formerly VH AWE. I knew both pilots of the 757 and my heart felt condolences go out to their family and all their friends who are no doubt suffering beyond belief at this most tragic time, as am I. Obviously condolences also to the family and friends of the TU154.

Another point which troubled me somewhat was the release of the crew's name in the media before family had been informed, how this can be allowed to happen is mind boggling to me.

foxmoth

2nd Jul 2002, 11:40

Another question. If the controller had no respose from the russian a/c, why had HE not instructed the 757 to climb? If the TU154 had not started its descent when the 757s TCAS initiated there is no reason for TCAS to tell the 757 to go up rather than down, by the time the reversal would have come in it was probably to late.

md80forum

2nd Jul 2002, 11:40

Aviation-bitten media worker as I am:

15 hours after the Überlingen crash, it is interesting to see how the media tide is geared against the Russian counterpart of the accident, even though there are strong indications that a TCAS malfunction/misinterpretation or slow Swiss ATC response may have contributed to the crash as well.

This is, however, only informed backstage talk. Watching the Big International TV channels the only thing we see is Tupolev wreckage, Aeroflot-heritage stories, background on a remote Bashkirian aviation enterprise. Where is DHL ? Background on their ops ? Incident records ? The pilots personal records ? Bahraini aviation authorities' followup capabilities on safety - the plane was on reg there ? And where is the whole 757 for that matter ?

It appears it's easier to sell TV commercials to a worldwide courier chain than to the flag carrier of an autonomous forgotten Russian republic, and to organize your reporting accordingly.

Is it me that is being cynical ? Or them ?

Jan-Erik Andelin EFHK

Fox3snapshot

2nd Jul 2002, 11:44

Hi foxmoth,

Without knowing the displacement of the traffic, the amount of traffic and frequency conjestion etc. it impossible to guess, there may have been traffic above the 757 which precluded a climb.

Alpha Leader

2nd Jul 2002, 11:55

From a release by Swiss news agency SDA at 1306 today:

By belatedly obeying ATC instructions to decrease altitude, the crew of the TU-154 set off the TCAS of the B-757 freighter approaching at same flight level, which caused the Boeing’s pilot to dive, too. This is the immediate cause of this collision, and the air traffic controllers on duty are – for the time being at least – free of blame.

According to Anton Maag, Manager of Skyguide’s Area Control Centre, speaking at a media conference held on Tuesday morning at Zurich Airport, the situation until immediately prior to the mid-air collision had been entirely normal. Given the time of night, few aircraft were in the sky.

One of those up there was the TU-154 operated by Bashkirian Airlines on a charter flight from Moscow to Barcelona via Munich and Geneva. Flying from south to north towards Brussels at the same time there was a B-757 freighter of DHL. Both aircraft were at 36000 feet. Their flight paths were to cross at Ueberlingen – a routine event.

For this crossing, the controller at Zurich ATC wanted the Russian aircraft to descent to a lower flight level, as there was going to be a scheduled landing at Geneva anyway. Between 8 and 10 nm (or approx. 1 ½ minutes of flight time) prior to the crossing point ATC instructed the TU-154 crew to initiate a descent – but this instruction was not confirmed. A second identical advice also remained unacknowledged. It was only on the third attempt that the TU-154 crew reacted and began to seek the assigned, lower flight level.

In the meantime, the TCAS on board the B-757 had registered the approaching TU-154 at the same flight level and instructed its pilot to descend. According to generally accepted international practice, TCAS warnings and instructions are adhered to immediately and without clearance from ATC, according to Anton Maag. Between 2335 and 2336 hrs the two aircraft collided at 35300 ft.

According to Anton Maag, the timing of the first set instructions to the TU-154 crew to descend was not ideal, but would have sufficed “under normal circumstances”. And Skyguide spokesman Patrick Herr insists that the type of instruction and the timing of the upcoming crossing of flight paths were going entirely to SOP.

The two “sticking points” that the investigation would have to concentrate on were, according to Patrick Herr

1) Why did the Russian crew not react immediately to the first set of instructions issued to them by ATC?
2) And why did the TCAS on board the B-757 instruct its crew to descend?

There were apparently no language problems whatsoever. According to Anton Maag, the preceding conversations with either flight deck had been entirely normal. The Russian pilot, says Bashkirian Airlines, was 52 years old and had some 10 years of experience behind him. The controller on duty, according to Patrick Herr, also has many years of experience on the job.

The TU-154 approaching from the east had been handed over by German ATC to its Swiss counterpart (which is responsible for that particular sector despite its location above German territory) at 2330. The flight had been advised in a timely fashion, too. The B-757 freighter had crossed the Italian-Swiss border (to the south of the collision site) at around 2300.

At the time of the actual collision, there was very light air traffic, with only a few aircraft in the sky. The two controllers on duty in Zurich had only one sector to look after.

Thanks for your appreciation, atc_ring

Electric Sky

2nd Jul 2002, 12:02

I am not going to speculate on the reasons for this terrible crash as I and none of us know all of the facts.

With regard to TCAS, there are many many traffic conflicts that occur that would otherwise have resulted in a possible collision. Instead of complete devastation all that happens in the majority of cases is a bit of extra paperwork at the end of a flight. As long as there are at least 2 aircraft in the same region of airspace there will always be a very small risk of collision, particularly when only 1 has TCAS, but TCAS is something I would not leave base without particularly as the skies become more and more congested. Should TCAS be partly to blame for this accident it's benefits far outweigh it's flaws.

ES :(

zoru

2nd Jul 2002, 12:05

according to swiss atc their controller (s) had both aircraft under their control for a good ten minutes before the crash,on a converging track.

why wasnt the dhl aircraft vectored behing the tupolev?if as reported the tupolev was slow to respond to descent instructions.do atc rely too heavily on tcas to prevent collisions?i am not trying to apportion responsibility.

god rest all involved

foxmoth

2nd Jul 2002, 12:17

[(2) And why did the TCAS on board the B-757 instruct its crew to descend? ]

If the TU had not started its descent, this is what TCAS is designed to do - it has no way of knowing if the other a/c is going to go up or down until it happens! Once it detected the TU descending it can change the descent order to a climb order, but it was probably to late by then. Even if the first descending A/c had the second visual at this stage, it may have been to late.
If BOTH aircraft had working TCAS, THEN they "talk" to each other and make sure one aircraft goes up and the other down.

Nopax,thanx

2nd Jul 2002, 12:41

Our thoughts are with you all at DHL at this very trying time...you are, under normal circumstances, our greatest competition. We all share Europe's crowded skies, and are one part of the same family when the chips are down. I hope you find the strength that you need in the days to come.

Good luck to all.

Volume

2nd Jul 2002, 12:49

It is now confirmed 52 children were on bord the 154, recieved a free holiday in spain because of their outstanding good performance at school. :( very sad :(

Both recorders are now recovered from the 154 wreakage, the german BFU is the only western air accident investigation agency which has the equipment and the specialists to analyse russian flight recorders.

02.07.2002 05:00
BFU Press release (http://www.bfu-web.de)
Actual Aircraft Accident

On July 1st 2002, 23:35 MESZ (21:35 UTC), well above the Bodensee a midair collision happened with a B757-200 (DHL) and a TU154 (Bashkirian Airlines – Russian Ferderation). The RNAV-Route Salzburg-Traunstein-Kempten-Trasadingen was used by the TU154 while B757 flew along RNAV-Route ABESI-AKABI-TANGO, both aircraft approached each other at FL 360. The collision took place close to AKABI at FL 354. At the time of occurrence both aircraft were under control by Zürich ACC.
The accident is under investigation by the BFU.

An investigation team is out to arrive at the accident site and to meet the investigation team of the Police in Friedrichshafen.

Momentarily the follwing is known: B757-200 / TU154

Aircraft Operator: DHL / Bashkirian Airlines
People aboard): 2 / ca. 57 + 12
Departure Aerodrome: Bergamo / Moskau
Destination: Brüssel / Barcelona
Flightplan:
Mode of operation: Cargo / Charter PAX-Transport
People killed:
People hurt:
Aircraft damage: Both aircraft crashed
Third party damage: Buildings and environmental damage
Phase of flight): cruise
Type of accident: Mid Air Collision

As soon as new information is available, it will be published on the BFU-internet-homepage or released.

Ergänzung der BFU-Presseinformation von 05:00 Uhr
(Supplemental Information, 5am UTC)

Eine erste Auswertung des Sprechfunkverkehrs der Schweizer Flugsicherung mit den beiden Flugzeugen hat ergeben, dass die Besatzung der TU 154 ca. 50 Sekunden vor dem Zusammenstoß die Anweisung bekam, von Flugfläche 360 auf Flugfläche 350 zu sinken. Dieses Sinken war für den Weiterflug nach Barcelona notwendig und war gleichzeitig eine Maßnahme, um einen Höhenstaffelung zu der Boeing B 757 herzustellen.

(Analyzing swiss radio recording, the 154 was advised to sink from FL360 to FL 350 50 seconds prior to the collision, this altitude change was already planned for the flight to barcelona and an action to achive separation with the 757)

Während die Besatzung auf eine erste Aufforderung nicht reagierte, reagierte sie auf eine zweite Aufforderung und begann den Sinkflug ca. 25 Sekunden vor dem Zusammenstoß. Kurze Zeit später begann auch die Boeing 757 aufgrund einer TCAS RA zu sinken. TCAS bedeutet „Traffic alert and collision avoidance system". Dies ist ein Gerät, das die Besatzung eines Flugzeuges vor anderem Flugverkehr warnt und der Besatzung Anweisungen gibt, wie zu reagieren ist, um einen Zusammenstoß zu verhindern.

(Ignoring the first advise, the 154 crew started to descend 25 seconds before the crash, shortly AFTER the 757 also started a descent due to an TCAS RA [...])

Warum die Warnung dieses Gerätes ebenfalls zu einem Sinkflug der Boeing 757 führte, ist noch unklar und wird Gegenstand weiterer Untersuchungen sein.

(Further investigations will show why the warning advised a descend for the 757)

So maybe someone put the blame on the russians much to early ?

:( Verry, verry sad, condolences to all involved :(

ETOPS773

2nd Jul 2002, 13:18

Of all the places..no one would have thought there.
What a horrible way..and all those kids.

Condolonces to all,sad day.

A Nonny Mouse

2nd Jul 2002, 13:31

From the above posted by Volume, it seems that the TU154 received its first instruction to decend a mere 50 seconds before the collision.

It also seems that the pilot did not respond to the first transmission, but did to the second which followed. Is it really that unusual that pilots miss their first calls (especially at night)?

It does seem a little late in the day to be carrying out a planned descent to achieve separation. I would have thought that with only 50 seconds to go to the 2 a/c meeting some avoiding action might have come in useful, and might of grabbed the pilots attention.

This is of course all conjecture going on the statement filed above.

B=But blaming the Russian's for this (as the media are already starting to do) seems a little out of order!

willadvise

2nd Jul 2002, 13:31

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 to late to initiate a level change. This leaves no time at all for Plan B or Plan C for solving the conflict if Plan A doesn't work. We are taught "separation assurance" in case of radio failure and I suggest that in this case there was none.

brabazon

2nd Jul 2002, 13:32

From the BBC's web-site:

Pilots have already hit back at the early Swiss move to blame the Russian pilot.

"It seems incorrect to me for Swiss air traffic control to be already publicly blaming the Russian pilot 'because he did not respond to calls'," said one contributor to the Professional Pilots' Rumour Network.

"Why did they not co-ordinate this action with the DHL aircraft?"

Others said pilot fatigue and language problems might prove key.

"Tragedies like this are caused by governments and authorities not addressing the problems we encounter every day," one writer added.

Perhaps it's time for condolences and reflection rather than theorising...

eratic

2nd Jul 2002, 13:33

md80forum>

isn't the DHL plane in the lake and the reason there's no TV visable wreckage and why they've not recovered the recorders yet?
you're right, though, people aren't seeing any DHL logo'd wreckage merrily burning away 5 metres from some person's house which is probably psychologically a better thing for DHL's (potential) customers.

how transparent is the Bahrain aviation authority likely to be? have the full findings of the last GF crash even been revealed yet?

OneWorld22

2nd Jul 2002, 13:44

Terrible day.....

From what I was told, I can post this information about the DHL
757,
Reg: A9C-DHL
Type:757-200SF
Serial no:22175

I also got the Insurance incident mailshot, which I can't reproduce here but it has nothing major to report.

Based off the top of my head the DHL schedule would have been something like the following,

DEP BAH 1600 ARR BGY 2200
DEP BGY 2300 ARR BRU 0020

So that would give a 10 hour duty time for the crew.

I've given my condolances to colleagues in Brussels and am trying to get a contact detail to do the same for Bashkirian, does anyone have one?

Hogg

2nd Jul 2002, 13:55

Sent u their contact details via ure Email.

Hogg

Standard_Departure

2nd Jul 2002, 14:03

As an ATC, the following things make me wonder....

*1.
If the aircraft were at the same level inbound from the Italian and German sectors respectively, then surely the Swiss sector should have co-ordinated a different level for one of them prior to entering the sector (less than 10 minutes before impact)?

*2.
Does the Swiss Sector have MTCD (Medium Term Conflict Detection) which would give about 10 -15 minute warning of conflict? If so, what was done with this MTCD information?

*3.
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..

*4
At what point should ATC leave the avoidance to the respective TCAS's, and

*5.
Will pilot's respond to ATC or TCAS as priority ?

These are questions that are raised in my mind as an ATC. No intent to blame anyone..

DW11

2nd Jul 2002, 14:07

Some interesting comments from a DHL spokesman interviewed on television at lunchtime today.

All DHL aircraft are TCAS equipped.
All European aircraft are TCAS equipped, Russian aircraft are not.
The collision was caused by the Russian pilot.

So there we have it, no need for an accident investigation. DHL have already investigated it, and apportioned all blame to the Russians.

Volume

2nd Jul 2002, 14:13

To my information, the 154 was also TCAS equiped

Anne.Nonymous

2nd Jul 2002, 14:15

Standard Departure

Can't answer the first four points but, prior to today, as a pilot I would ALWAYS follow TCAS in preference to an ATC instruction. It is there to resolve the confiction for BOTH aircraft. However, it will be interesting to see the final outcome of this tragic affair. Maybe TCAS may be seen in a new light.

flch10000

2nd Jul 2002, 14:18

My first thought is with the poor Children and their families as well as both crews. The final moments must have been indescribable and horrific beyond words.

Although speculation is no doubt human nature perhaps we should show some respect towards all connected to this terrible tragedy by not overly speculating on causation at this stage.

canberra

2nd Jul 2002, 14:29

a few thoughts from a non pilot.
1, condolences to all relatives.
2, as an ex raf rescue co-ordinator i would like to know where the press got their initial casualty figure too. one night dundee had a beech 200 crash in the undershoot to rwy 10, he had 3 on board . within 2 minutes of the incident we had a call from the daily express about an aircraft missing near the tay bridge with 53 on board!
3, someone has already mentioned it so i will as well, were the crew of the 154 awake? it wouldnt be the first time crews have fallen asleep, and it wouldnt be the last unfortunately.
4, and of course there is the language problem.

DontPanic_DontPanic

2nd Jul 2002, 14:34

STD-DEP:

1. The entry levels via those two points were correct for the direction of flight of the two aircraft. The 757 , via SRN, would have been on the freq. for quite a wee while before the T154 in at KPT.

2. Yes, Zurich does have Short Term Conflict Alert , but it seems it was off for maintenance. Usual procedure to do so during the night shift.

3. 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 immediatly respond/comply. It's a sad reality that pilots do not always do what we tell them to do immediatly.

But what is emerging and is of real concern regarding TCAS is that the DHL TCAS " Descend" command came AFTER the T154 started to comply with the ATCO's instruction to descend to FL350. Why would it give a descent command against conflicting traffic alreading descending ?

vertigo

2nd Jul 2002, 14:56

Anne.Nonymous,

As an ATCO I do agree with you about following TCAS over ATC instructions, this is what we expect. However there are many potential problems when following this course of action.

TCAS provides generally inaccurate guidance in azimuth.
I believe TCAS displays targets anywhere in a 30 degree arc. Therefore a target in your 12 o'clock may be 15 degrees either side.

TCAS will resolve the conflict for both aircraft, but that may put the aircraft in further conflictions. This is particularly true if flight control inputs are excessive.

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.

I offer no speculation on this tragic accident, merely stating TCAS is not perfect and all of us should endeavour to understand its limitations.
I'm sure there will be lots of lessons for all of us from this tragedy.

OneWorld22

2nd Jul 2002, 14:58

Thanks a lot for sending that, could I ask you to send it once more as I didn't get it yet, my e-mail account seems to have been dormant. I've just reactivated it.

Thanks again.

Pontious

2nd Jul 2002, 15:01

Please feel free to correct me but wasn´t there an incident over Asia a few years ago where a BA(?) 744 came perilously close to another aircraft(Chinese747?).Conclusion was that 1 or both aircraft were provided with incorrect TCAS instructons.
The impending collision prevented by 1 or both aircrew responding to visual contact with the other aircraft,both aircraft missed each other by a couple of hundred metres.Anybody else remember that one?
I´ve flown over the block of airspace where Zurich/Rhein/Vien ACC´s border regularly for most of my professional career and often had radar vectors/Cruising Mach no. alterations/level changes for traffic avoidance with conflicting aircraft sometimes 2 or 3 ATC sectors or even Countries away.
NEVER 1 minute to loss of seperation!Something here doesn´t add up.I would prefer to hear the A/C -ATC voice transcripts before voicing an opinion.Any operating aircrew or scanner radio enthusiasts catch the instructions given by ATC?
Accidents are rarely the result of one factor,more a combination of events snowballing out of control.
Keep It Safe,Stupid!
Heart felt sympathies to all.:confused:

Capt PPRuNe

2nd Jul 2002, 15:10

Firstly I would like to ask that we try and keep this thread along the lines of procedures and technical issues. Whilst it is an emotionally tragic accident and many would like to offer their condolences, this is not the place to do it. Please feel free to start a condolences thread on the Aircrew Notices forum.

Secondly, I would like to point out that what I have seen so far in the media is once again biased reporting of distorted facts interspread with assumptions of blame based on whoever has the most effective press agent. Whilst we cannot prevent speculation as it is only human to do so and calls not to specualte on here will be fruitless, at least we can hope for some 'informed' specualtion and discussion on PPRuNe. Anyone posting what I or other admins consider to be frivolous, insulting and/or anything that just sounds like someone wanting to see their username on this thread will have them deleted.

As has already been mentioned in a few of the other posts and picked up on by the BBC is our questioning of the Swiss reports (and apparent conclusions) that it was purely pilot error on the part of the Russian crew. I too find it incredible that both aircraft were not at least put on radar vectors to assure separation as a prelude to issuing a descent request to the Tu154. Whlst I am not an expert, but having flown through that airspace more times than I care to remember, the standard of controlling is usually very high. If as has been stated that the STCA equipment was out of service why did the controller leave the request for a descent so late? Surely at that time of night when traffic is nowhere as busy wasn't the decision made earlier to descend or vector the traffic?

How many times, especially at night have any of us missed an initial call? It doesn't matter whetner the crew of the Tu154 were Russian because it can and has happened to just about every one of us at one time or another that we have missed a call from ATC. The mix of accents is one reason and there is nothing we can do about that but also there is the 'callsign' itself. If the Tu154 was not a regular in that airspace it is possible that its callsign was not familiar to ATC and the identifier on the strip bore no resemblance to the callsign familiar to the crew. Flying for a new airline myself I have missed calls that controllers have made because they assumed that the three letter identifier on the strip meant something totally different from our callsign.

After a thorough investigation we will all be wiser and have learnt something from this tragedy but as we all know it takes time. In the meantime we are free to discuss the issues here and hope that the media luvvies pick up on sensible debate and not their usual misinterpreted sensationalism and as we have seen today, premature blame. As in any air accident there will be a chain of events, any one of which could have prevented the disaster. Ultimately the pilots get the 'blame' because the media luvvies need a scapegoat in their usual 'dumbing down' of facts but as we all know it should come down to a distribution of responsibilities over a series of events and we should hopefully become safer in the future. A high price to pay unfortunately.

Suggs

2nd Jul 2002, 15:13

I find TCAS to be very accurate in all respects. There is no bigger wake up call than the 'TRAFFIC' booming in your ear from that speaker. When that happens my hands instinctively go for the thrust levers and the control column, thumbs poised to disconnect the automatics. But making a rash decision to quickly is a danger we must guard against. From training I do what TCAS says not what ATC say. Even if I'm visual with the A/C there is alwasy the possibility that in busy skies I've Identified the wrong A/C.

Within the last month I've been down to Venice through those same sectors at that time of night, it's was very quite. Low conntroller work load, not many birds around.

The cause of an accident is never any one issue it's a chain of events that leads to fatal consequences.

Why wasn't the 154 and/or the 757 given vectors a good 5 minutes previously?
Were all members at the controls or taking a toilet brake?
Was everyones TCAS working, was it switched on?
Was the scale on the Nav display turned down to a low enough scale, thus reducing one or everyones mental model?

Whatever happened it could have been any of us.

My condolences to all those families who have lost loved ones.

Plane*jane

2nd Jul 2002, 15:21

I was Brants CRM Instructor in Bahrain, and absolutely devastated he is one of the dead. A lovely young man and how dreadful it is when you know someone involved in these horrific accidents. It's bad enough in instruction anyway analysing them without that personal tie.
My heartfelt sympathies with Paul and Brant's families, and DHL as this must be a real body blow to a very close knit and well run organisation. DHL in Bahrain is one of the most forward thinking Companies in CRM education I have encountered.
Last and not least sympathies to the poor crew and passengers of the Tupolev. Let us not judge at this point until we know all the facts. No-one intentionally gets things wrong.
Tragic loss of life and adds to what is turning out to be one of the worst years in fatalities worldwide. And we are only half way through

Spodman

2nd Jul 2002, 15:25

Recently did some interesting ATC simulator training. We sat with out backs to the screens until the Short Term Conflict Alert went off (10-20nm before returns merging) then turned around and tried to fix it. This is not separating, it is collision avoidance when separation has failed. Brilliant fun, but unknown realism, with the blip-drivers reacting immediately & turning the right way most of the time.

How to do this has changed with the advent of TCAS. An excellent CAA (UK) manual on the subject (which I have forgotten where I got, but was available on-line) suggests "leaving the vertical" to the TCAS to sort out, with ATC input restricted to headings, unless a full vertical separation standard (less likely to set off a TCAS) could be maintained. (My paraphrasing.)

These techniques are not documented anywhere, as yet, in our (Australian) manuals, and not everybody I work with has yet undertaken this training.

For every pat solution developed somewhere there is a reason it will not work somewhere else. Nothing I have said should be taken as a critisism of anybody. I will wait for the outcome of an investigation before I offer any opinion on this accident, but would encourage ATC everywhere to try these techniques and situations first in the simulator.

sponix

2nd Jul 2002, 15:34

Obviously it goes without saying that our thoughts here go out to those involved and I for one hope the cause can be found and action taken to prevent such a tragic loss of young lives in the future.

Much speculation has been made (here, in the Media and elsewhere) as to why (if?) the TCAS system directed the Boeing pilot to descend when the Tupolev was already in descent.

From doing a google seach it seems that there have been a number of occasions where a TCAS system has incorrectly directed a pilot to make a manouver that has put two aircraft on a direct collision course. It is only through the skill and judgement of the pilots (And perhaps good visibility) that a disaster has been averted.

It should also be remembered that last nights tragedy occurred during darkness..maybe if visibility had been better disaster could have been narrowly avoided.

Without wishing to pre-judge any investigation, serious attention needs to be paid to the TCAS system on board the aircraft and pilots need to be made aware that these systems are far from infallible.

More on previous TCAS "incidents" here:

http://www.aaib.dft.gov.uk/bulletin/jun01/cggwd.htm
http://www.rpi.edu/~woodhe/docs/wsj/flawed.txt
http://www.atsb.gov.au/aviation/rec/r19990159.cfm
http://news.airwise.com/stories/99/11/942324329.html

Standard_Departure

2nd Jul 2002, 15:36

Technical Question,

There are two types of (ATC) conflict avoidance tools referred to here;

Firstly, STCA (Short Term Conflict Alert), this usually gives an alert toward a conflict predicted within the next 90 seconds, in an Area environment, this would be very late, considering closing speeds and the likes. I would expect this is primarily used in an Approach (Terminal) environment.

Secondly, MTCD (Medium Term Conflict Detection), this usually detects conflicts in the next 15 minutes, which is not very appropriate for use in an Approach environment, but more readily used in an Area environment.

These are usually functions of the Radar Workstation, and as such should not be down for maintenance, it is a selectable function of the Radar Controller, furthermore, if one Radar Workstation was down, there should be a second (or more) workstation in the room that was operational and could have detected the conflict. STCA and MTCD are not like VOR's or ILS's that are removed for maintenance, they are integrated in the Radar Workstation.

The question is;
does this Swiss Sector have STCA and/or MTCD?

Capt Pit Bull

2nd Jul 2002, 15:45

Just a few observations:

If, as reported above, the t154 left its level 25 seconds before collision, then that would have been just a few seconds after the B757 responded to its RA. Almost a worst case 'RA Reversal' Scenario.

Can anyone state categorically the TCAS fit on these aircraft?

Particularly Version numbers?

It is a not well known, but very important fact, that TCAS versions prior to 7 can not reverse when the RA is coordinated.

i.e. if either aircraft manoevres against the RA then you are both in big trouble.

Thats one of the reasons that the JAA ACAS mandate only deems v7 to be acceptable.

Is anyone still operating on v6.04 grandfather rights? If you don't know, ask one of your avionic engineers.

CPB

purr

2nd Jul 2002, 15:58

with an aircraft approaching both the crew would have been on their toes because both sets of crew would have been in "contact"on the map with a zero next to the A/C symbol When the russian aircraft started it descent a little arrow would have pointed out its vertical path on the DHL aircraft's map provided the vs of the descending A/C was greater than 500ft/min the crew on the DHL obviously did not get this indication on their map due to the RA .
Is it a practice in those skies for an aircraft to announce Left level ........ for Level........ when advised by ATC to descend:confused:

Ruslan

2nd Jul 2002, 16:03

Sorry guys and with all respect, Capt PPRuNe, makes me post in here
Please STOP blaming Russian crew.

1. They’ve been used on this aircraft and that crew for 3 YEARS period on Barcelona direction
2. They’ve have quite good experience on type and language
3. Obvious ATC error, you should be blind or something, I don’t believe you haven’t heard THE RULE: NO READBACK – NO COMMAND GIVEN, IMMEDIATE ACTION SHOULD BE TAKEN
4. Russian RA86816 is RVSM able, ACAS equipped, in fact, the Tupolev 154 had been observed flying over the height monitoring station in Linz (Austria) less than an hour before the accident and the height-keeping performance conformed to the RVSM status
5. I believe Russians have facing TCAS alert with climb advisory in one hand and following repeatedly command from ground to descend (lets wait for some CVR facts)
6. At this time I’ve been informed that Authority of Bashkirian Airlines has start claim procedure for Swiss ATC

Please no findings who is guilty, it is really big tragedy for all of us Russians, visiting your friendly forum desk.
Thanks

Seloco

2nd Jul 2002, 16:04

To Purr and others:

It is clear from the published maps and text that the two aircraft were approaching each other virtually at right angles, rather than head-on. In that scenario TCAS is presumably programmed to call for a change of height (up or down) rather than heading to resolve the conflict.

Capt Pit Bull

2nd Jul 2002, 16:14

Sponix,

The incidents you list above, whilst certainly part of the communities TCAS learning process, are somewhat dated. To the best of my knowledge the issues raised have been addressed.

v7 TCAS compares the airdata presented to both transponders, not just the operating one, and flags 'Altitude fail' if they disagree, which disables the TCAS. So for erroneous altitude encoding to nail you, both ADCs have got to be in error by the same ammount, and become so at the same time. Highly unlikely.

As mentioned above, it appears the b757 manouevred first. From reports above, and the crews call to ATC, a descent was flown.

Someone else maintains that the t154 was also TCAS equipped.

If if it was equipped, (and on and serviceable), then they will have been receiving a 'Climb RA'. They descended. TCAS should still have been able to ressolve the situation by issuing a reversal to the b757 UNLESS it was pre version 7 (see my post above).

If it was not equipped, (or off) then they obviously followed their descent instruction. In this case, since it would not be a coordinated encounter, the b757 TCAS would be able to issue a reversal regardless of software state.

Now, pure speculation I admit, but lets say you are flying a non TCAS aircraft and you suddenly realise that ATC want you to descend urgently. As you commence your descent, you hear another aircraft saying 'TCAS Descent'. What goes through your mind?

CPB

EuroBerlin

2nd Jul 2002, 16:19

Here is a link that takes you to the press releases by the german air accident investigation body.

http://www.bfuweb.de/aktuinfo-e28.htm

Gives you some info on flightpaths and as far as I can see is free of speculations and defensive actions like what I believe to see from the Swiss side now.

purr

2nd Jul 2002, 16:23

RUSIAN no one has blamed anyone they are just trying to figure out what happened no one wants to be the next.:rolleyes:

Capt Pit Bull

2nd Jul 2002, 16:28

Seleco,

The current TCAS system, (TCAS 2) can only provide vertical collision avoidance. The reasons behind this can be read elsewhere on this thread, or do a search in Tech Log.

Ruslan

No professional pilot is going to try blame anybody until a full investigation is out (and probably not even then - more than anyone we realise how an honest mistake under time pressure can appear negligent to an armchair pilot).

However, can I just point out that if your belief number 5 is correct, then they, or their training, were at fault. I'm sorry about this, but you are the one suggesting that they had a climb RA that they manouevered opposite to.

CPB

Standard_Departure

2nd Jul 2002, 16:43

Based on the skyguide (Swiss ATC) press report, the first command to the T154 to decend was issued about 50 seconds before impact;

It will be interesting to see if the ATC used the words ..."Avoiding Action" or ..."For Traffic Avoidance" in this transmission.

I cannot believe that it is standard procedure to allow aircraft to be on converging headings at the same level with 50 seconds to go before crossing

Ruslan

2nd Jul 2002, 16:53

Capt Pit Bull

Thanks for understanding and your kind input, but should note, your post or whoever is under Capt PPRune, makes me say in here. I do appreciate learn from this tragedy and prevent such kind of things to ever happen.

As for point 5, fully agree, but let’s wait for some CVR’s speculation before the verdict who has trained well enough

Ruslan

2nd Jul 2002, 17:00

Further to my previous post, I've found very unusual to see TCAS alert on cruising and no one word regarding ATC/RVSM conception at all ..

A Nonny Mouse

2nd Jul 2002, 17:00

Have a listen to this interview with a SkyGuide spokesman.

He claims that getting aircraft which are on a converging course at same levels to change levels when they were only one quarter of a minute apart is normal Swiss procedure!

Am I the only Air Traffic Controller who finds this completely unbelievible?

http://news.bbc.co.uk/media/video/38111000/rm/_38111995_plane16_mark_vi.ram

Capt Pit Bull

2nd Jul 2002, 17:00

Fair enough Ruslan.

And anyway - lets not forget that even if this does turn out to be the case, the crew concerned may have been the last link in a sequence of events, but they weren't the only link.

CPB

NigelOnDraft

2nd Jul 2002, 17:02

I agree all should stop over-speculating.

This is not helped at all by Swiss ATC and DHL indulging in blaming others already.

Since Swiss ATC have put their side, I feel the following thoughts:
1. 8-10NM (at 90deg) is far too late to describe as even "less than ideal". As someone else said, will be interesting to say what urgency prefixes were applied to the calls.
2. A Plan B is required here - the second call maybe, and certainly the third call should surely have been to the DHL ac? There are a number of legitimate reasons why the Russian aircraft did not, or could not respond. There is, for instance, a known issue with some radios in our fleets where they "go to sleep" and aircraft have not responded for minutes to call. Advice to us - if you don't hear something for a long time (which would be along time at night), click the Tx key...
3. IMHO, the Russian pilot could only be "blamed" if he read back the instruction, and only THEN did not comply.
4. Leaving it so late to start avoiding action, not only increases the possibility of collision by no response (which did not happen here), but TCAS getting involved.
5. Hard to blame TCAS ?? Basically, the 2 anti collision systems (ATC and TCAS) were both "working" in a "just in time" manner - and unfortunately took the 50:50 worst case. TCAS is designed to be a backstop to ATC, and hence is "just in time". ATC should not be...

I do not like pointing the finger, but am very concerned by Swiss ATC throwing the mud. IMHO, in that they have started throwing it, its alright to throw some back...

NoD

Mister Geezer

2nd Jul 2002, 17:59

A terrible accident. Thoughts are with the bereaved. One interesting point was that the TU-154 was very new for its type, being rolled off the line in 1995. In fact newer than the 757 that was involved.

It could have been a lot worse; I dread to think of the damage that would have been caused if two heavies collided over a large city. A lot of us (me included) thought that with TCAS in use, mid air collisions were a thing of the past. No doubt RVSM will be put into the spotlight in the wake of this event. I hope the hard work done by ATC in implementing RVSM will not be wasted.

MG

Snakum

2nd Jul 2002, 18:04

Every time there is an accident the circumstances are - logically I might add - discussed ad nauseum by pilots, engineers, ATC, cabin crew, and even spotters. This is to be expected. I too use these discussions as a learning tool, even though I'm still only on small aircraft.

And envariably, some a$$ will pipe up whining about all the speculation .... "Why don't we wait for the investigation ... blah blah blah ...." "You have no right to speculate .... blah blah blah .."

For those that whine on and on about the post accident discussion ... go $%#& yourself, alright? We (most of us) are pilots and the conversations here are no more than that happening around the world at airports and FBOs everywhere. It's with both a morbid curiosity and for the sake of knowledge that we exchange ideas about these tragedies. If it offends you ... DON"T EFF'N READ IT!

PO'd ...

Minh

Rananim

2nd Jul 2002, 18:07

Two observations:
a)An ATC has a traffic conflict between 2 aircraft.One is local,the other foreign.One speaks English fluently,the other has at best a moderate understanding of aviation English.He knows the command he gives must be acted upon immediately.To whom should he give that rapid fire command?Requires intuitive and lightning thinking I agree but a lot of ATCO's fit that bill.
b)Having received no response first time from the first a/c,why waste time with a second attempt.Go straight to plan B and give an opposing command(ie.climb,or turn if climb not available) to the second a/c?This raises the question of which command the 2nd pilot must follow?His TCAS command to descend or the ATC command to climb?

Too early to judge or speculate even...the fact that a handoff had just occured makes it more difficult for the ATCO...he hasnt had a chance to ascertain the communication skills of either aircraft.But he would be correct in assuming that his best chance for quick compliance came with the DHL a/c not the Russian.To exclusively pursue the Russian a/c because they were the offending party(wrong level) is too literal an approach.More lateral thinking needed.

Condolences to the families of all those involved.

nippa

2nd Jul 2002, 18:16

As a UK Area Controller I'm rather worried by what has been said about this " just in time " technique.
The comments made in this thread now seem to be supported by the Official Swiss Press Releases with the Russian aircraft having been given a very late descent clearance. I hope I'm wrong.

If I have crossing High Level traffic and have not acheived vertical separation by 20 miles , I reckon I've not done my job.
Sometimes where there is some uncertainty about acheiving vertical separation and 2 aircraft are "dead ringers" , you'll get a radar heading just to guarantee some sort of lateral spacing. Kinda makes me feel more comfortable!

Heaven knows what the final report will show although I'm sure TCAS will come under close scrutiny.
Over the years I've seen some weird resolutions that only an engineer could love!

Like all NATS controllers I've been half expecting something like this in UK Airspace.
The feeling amongst us is " Thank Christ it wasn't me!"

My prayers for everyone involved.

Lucifer

2nd Jul 2002, 18:21

Leading on from what BigBrutha says, I believe that this fact in itself shows the imperative to redesign the FIR regions of Europe, and makes a mockery of the claims that this would in fact denegrate safety which unions are claiming prior to the forthcoming Europe-wide strike.

I hope that this was not a TCAS failure like the BA incident over China, as this would have a serious implication for the integrity of the system. Enough speculation though, and lets wait for the authorities' conclusions.

I have to agree that I though DHL's spokesperson to be very offensive in what he said on BBC at lunchtime.

GlueBall

2nd Jul 2002, 18:30

ATC is definitely on the hot seat on this one. If the Russian crew did not respond to ATC instructions in a timely manner, then the onus was on ATC for issuing an immediate vector to the second (DHL) airplane to avoid converging traffic.

Too early to tell what the TCAS Resolution Advisory commanded, if in fact it had advised the DHL pilots to descend, or whether it had commanded a climb. Likewise, the TU-154's TCAS Resolution Advisory and its pilots' maneuvering response will come to light upon both airplanes' CVR and FDR analysis. :(

Noddy Staltern

2nd Jul 2002, 18:59

Does anybody know what is the standard altimeter fit on the TU-154? I am wondering whether it had standard (Imperial) altimeters or Metric altimeters. Would the the Russian crew have been flying at an indicated FL360 or at the metric equivalent?

lukewarmskywa*ker

2nd Jul 2002, 19:00

In response to some queries about the amount of time ATC leaves itself to solve conflicts, I make the following observations:

As a previous contributor wrote, the likes of London are very much a 'belt and braces' unit (the cliche they apply themselves).
Karlsruhe (Rhein) is also of the same mold: this is because the units are still built around 'time over point' conflict resolution. The radar is used to abuse this strip based information until it makes some kind of sense from a capacity point of view.

Certainly Maastricht, and by second hand knowledge Swiss control and Copenhagen, work in a slightly different manner. Although it is always considered important to keep in mind radio-failure or radar failure circumstances, the time-based margin of error is commonly around two minutes.
Inside this time, alarm bells ahould be going inside a controllers head, and via conflict alert with the equipment too. But I would stress that it is not uncommon for controllers to leave a situation to somewhere around this margin.

Reports that the last instructions were given to the TUP 50 secs from impact are meaningless without knowledge of the apparent urgency behind the message.
'Descend now'

'Descend immediately '

'Avoiding action. Descend... '

But what is even now obvious is that there were two aircraft involved, and yes messages should have been passed to both aircraft....
'Turn immediately left 60 degrees.... '

Problem solved.

Even as a controller, to my mind ATC has the most to answer at this time. And Christ I feel for them.

ID90

2nd Jul 2002, 19:17

Is this the first mid-air collision between two airliners over Europe since the BA Trident / Inex Adria DC9 around 1976?

HEATHROW DIRECTOR

2nd Jul 2002, 19:23

Lukewarm.. wrote "the likes of London are very much a 'belt and braces' unit (the cliche they apply themselves). Karlsruhe (Rhein) is also of the same mold: this is because the units are still built around 'time over point' conflict resolution. The radar is used to abuse this strip based information until it makes some kind of sense from a capacity point of view. "

As a London controller I don't understand quite what he means, although I will very readily admit to being a "belt and braces" man. Very little UK airspace is operated procedurally nowadays; it's certainly 100% radar in the busy areas. We employ flight progress strips as aide memoires, not primarily to determine separation. If we based our separations on times I dread to think what would be the result as ATC and aircraft "estimates" are frequently wildly inaccurate for many reasons. In the London TMA it's 100% radar control. Strips, telephones and other devices assist us but the tactical decisions are based on what we're watching on radar.

PaperTiger

2nd Jul 2002, 19:43

Common among the Western media hype and expert (sic) opinions is the claim that the Tupolev 154 is 'unsafe'.

For the record, the percentage of Tu154 hull losses (from all causes) is comparable to several US jets. viz:
5.9% of all Tu154s built have been lost.
4.8% of Boeing 727s
7.5% of Boeing 737-200s
9.7% of Douglas DC-9-30s.

source http://aviation-safety.net/statistics/aircraft.html

I expect most PPruNers knew this already, but maybe a journo will read this too.

Dunhovrin

2nd Jul 2002, 19:47

Further speculation to muddy the waters....

There have been at least 3 ASRs raised due to the following:

Over Siberia (I think only under procedural control): Aircraft A (British) at x metres has been warned about aircraft B (Russian - based in Krasnoryarsk (sp?)) on reciprocal track at x + 500m. As the ac approach A has been given an RA climb TOWARDS B. This is due to B's height being (mis-)reported by B's TCAS as ALSO BEING x metres. This then caused A's TCAS to initiate the climb.

As I said this has happened at least 3 times - all with the same aircraft B.

Now I know TCAS gets its height info from Mode C, same as ground ATC so I don't think the above is a factor here. However, I'm busy trying to dig out the tail number for ac B.

stagger

2nd Jul 2002, 19:54

Question - When two aircraft are about to come into conflict can ATC anticipate which will get a TCAS climb and which will get a TCAS descend???

boris

2nd Jul 2002, 19:54

I felt constrained to send the following message to the BBC in Manchester. Sadly, all too predictable.

This evening on your programme, your newscaster/presenter, Gordon Burns, referred to the mid-air collision between a Russian Tu 154 aircraft and a DHL Boeing 757 Freighter over southern Germany. He commented that the Captain of the Boeing emanated from Liverpool and that the collision occurred 'because the Russian pilot failed to carry out Air Traffic Control instructions to descend'. This is not proved. The Flight Recorder from the Russian aircraft has not yet been read and the Recorder from the Boeing has not yet been found. The bodies are hardly cold, yet your Mr Burns reports the reason for this catastrophe!

There are, in fact, several potential reasons and these will be looked at by the inquiry which will be set up. Most of these reasons will be of a technical nature and the cause of the collision will be ascertained and published.

My interest in this matter is professional in that I am the recently retired Operations Director of a large regional airline and have suffered from terrible howlers at the hands of well-meaning but ignorant reporters in the past.

One would really have hoped that the BBC was able to do better than this.

Yours truly.

STCA

2nd Jul 2002, 19:55

Speculation is natural, it also gives an insight to another possibility. As long as we know the difference between speculation and fact, then it is OK.

Here is my speculation.

Swiss ATC sector, late evening, quiet, nothing too demanding, reading book, feet up, maybe chatting about the World Cup Soccer.

ATC looks up, Oh Sh!!!!t, Gives decent instruction to T154.
Simultaneously, T154 gets TCAS RA "CLIMB CLIMB", initial reaction from T154 crew is slow due to contradicting instructions. They decide to do what they always do, comply to ATC, commence decent.

Almost simultaneously, DHL gets TCAS RA, "DECEND DECEND"

Sadly, after decending 700', they meet the other guy.

Conclusion, 2 aircraft that will meet at the same level in less than 1 minute, should have been seperated (already) 2 minutes earlier at the latest.... sorry chaps but it seems too obvious.

THIS IS ONLY SPECULATION, I PRAY THAT I AM WRONG.

UNCTUOUS

2nd Jul 2002, 20:14

From the Latest CHIRP

Loss of Communications

Since 11 September, my company has adopted a locked flight deck door policy. As a result of this, our only means of communication with the cabin crew is over our cabin interphone via the 'CABIN' selection on the Radio Management Panel (RMP).
The design of the RMP is such that, when a 'TRANSMIT' button is depressed, the associated receiver is automatically selected. However, a receiver can be selected by separately depressing its button, thus enabling more than one function to be monitored at a time. However, as far as the VHF selections are concerned, with ANR headsets it is normal to monitor only one frequency at a time i.e. the one that is being used for transmission. The consequence of this is that when a alternate 'TRANSMIT' selection is made, it de-selects the in-use function (usually VHF 1) in transmit and also receive.
Thus, if VHF 1 is in use and being monitored, when the cabin crew call, the 'CABIN' button is depressed, which de-selects the monitoring on VHF 1. On two occasions now, I have needed to get involved in the conversation and have selected 'CABIN' also, without appreciating that we were both not monitoring our radio. This situation continued for at least a minute or two.
Perhaps I haven't thought about it before, but it seems to me that there has been an increase lately in pilots failing to respond to air traffic calls. Could our ATC colleagues comment?
I believe that, with these new procedures, we should have a completely separate cabin interphone system, which is not accessed via the RMP, thus removing the accidental cessation of monitoring the R/T frequency in use.

Chirp Response

Some operators have specific policies designed to avoid a situation where both pilots might not be monitoring the ATC frequency.
Within the UK, the number of recent cases of pilots failing to respond, although not significantly different from that previously, is a significant concern. More generally, it is understood that the Joint Aviation Authorities are fully involved in an investigation into loss of communication incidents in European airspace.
This is one of several reports that we have received describing difficulties associated with the changes recently introduced.

http://www.chirp.co.uk/air_transport/FB62.htm

Rwy in Sight

2nd Jul 2002, 20:16

Pls do not flame me.

In the summer of 99 I was lucky to see Pushing Tin The story of some ATC people with J. Kusak and J. Mulcovits. (forgive the spelling errors)

There was a line that I instantly fell in love with "An ATC is responsible for more lifes during one shift than a doctor over his entire carreer."

Tonoght I undersatand how serious this phrase is...

foxmoth

2nd Jul 2002, 20:29

Stagger
To answer your?, ATC has NO input OR feedback from TCAS so cannot tell WIHIH apart from the pilots rt & his radar display, but at the end of the day, TCAS should ONLY be giving orders if ATC has NOT done its job properly, so on this basis, even if TCAS made the wrong call, another call should have been made by ATC prior to this happening.

Captain Rodders

2nd Jul 2002, 20:46

Statistics can be made to mean anything you want.

Remember the TU-154 was still being built in 1994 whereas the other aircraft ceased production at least 10 years earlier. The fatigue life of the TU-154 was 30000 hours or 20000 cycles, how many of the 727,737 and DC9s are approaching (or have passed)three times those figures.

Hull losses per million flying hours may be more appropriate however as most accidents occur during take off or landing perhaps per million cycles may be even better. Each set of figures will give you a different answer.

Remember there are "Lies, damn lies and statistics" - Benjamin Disraeli.

The hull loss figures were quoted but why did you not include the following from the site

Please note that this table does not say anything about the safety of an aircraft type.

Figures do not disguise the tragedy - CR

stagger

2nd Jul 2002, 20:48

Well the media are reading what is posted here. This from the BBC...Pilots have already hit back at the early Swiss move to blame the Russian crew.

"It seems incorrect to me for Swiss air traffic control to be already publicly blaming the Russian pilot 'because he did not respond to calls'," said one contributor to the Professional Pilots' Rumour Network website.

"Why did they not co-ordinate this action with the DHL aircraft?"

"Tragedies like this are caused by governments and authorities not addressing the problems we encounter every day," one writer added.
http://news.bbc.co.uk/hi/english/world/europe/newsid_2082000/2082331.stm

foxmoth

2nd Jul 2002, 21:10

So it seems we may be striking back at the press tendancy to speculate too early - 1 up to Pprune methinks:)

foxmoth

2nd Jul 2002, 21:13

I also noted in the press reports that at least 2 of these incidents were NOT type related (ie. being shot down by a "rogue" missile!).

320DRIVER

2nd Jul 2002, 21:14

After seeing some posts re: altitude encoding problems from aircraft with metric altimetry systems, it would be good if someone really knowledgeable on this subject gave us his/her views!

RRAAMJET

2nd Jul 2002, 21:18

Condolences to all....very sad.

Some good posts, here, and sometimes (just sometimes) some idle speculation from aircrew brings up another investigation angle for the "experts". I heard that recently from a big wheel in the NTSB recently, at a conference dinner. They try, but can't always, think of all angles.....so PPRUNERS, don't necessarily be afraid to make informed speculations.

One other point here, to add to Capt Peacock's list:

For those of you who like to fly at night with the Cockpit lights on full bright in override because it's "less fatigueing", perhaps you might want to reconsider. Not saying it was a factor here, but lookout is as important as it ever was. ( Once had a relief crew fly me into the top of a rapidly building CB that they did not see, and had the radar tilted over the top of, resulting in a severe jolt and catering all over the place in the middle of the Pacific. I came out of the bunk to find sheepish faces in a full-bright flight deck - and lessons being learned)

PaperTiger

2nd Jul 2002, 21:28

Quite right CR, there is no single metric AFAIK which relates directly to the safety (or otherwise) of a particular type. But I do think the 154 gets a bad rep. for no particular reason other than it being a Tupolev. Undeserved IMO.

Wedge

2nd Jul 2002, 21:38

Nearly 24 hours after the accident, we are beginning to get an idea of how this terrible accident happened. As with almost all accidents involving professional aviation, it seems that this accident was multi-factorial in cause. I have my own theory on what happened and I hope I am not offending anyone by posting it here.

Swiss ATC (and it seems DHL) is blaming the Russian pilot, and Bashkirian Airlines are blaming Swiss ATC. I would imagine the truth is that the cause lay on both sides, and I think it's unfair for any side to 'blame' anyone because no-one wanted this to happen or indeed it seems was negligent to the point of being blameworthy.

Swiss ATC have admitted that the Tu-154 was given only 50 seconds to react to their initial call to descend. That in my opinion was the first cause of this accident. Error of Swiss ATC.

The pilot probably missed the first call. This is not uncommon especially in quiet airspace in the cruise at night when reactions are not at their most keen. To miss a second call is less common but does happen. However it seems this is what happened and that is likely cause number 2. Error of Bashkirian flight crew.

Thirdly, as has been suggested there was no instruction to the DHL 757 to take avoiding action when it became clear that the Tu-154 had not replied. Maybe the controller decided against this in preference to waiting for the expected reply from the Tu-154. Cause 3. Error of Swiss ATC.

By this time it is likely that both TCAS systems had given TA warnings and possibly RA warnings. If the TCAS operated correctly it would have instructed the Tu-154 to climb and the DHL 757 to descend. However crucially the Tu-154 had already been instructed to descend by ATC. Confusion, resulting in indecision followed by the decision to follow ATC's instruction. No human error - fault of the failure of the TCAS system to work as intended. Cause 4.

Cause 5. Bad luck. Even though both a/c were descending at the time of the collision, an accident was by no means inevitable as has been suggested on the TV news tonight. The chances of a collision were still small, especially since visibility was good. Instead of the catastrophe that happened, we would probably not find out about the incident for some time and it would be 'just another airprox incident'.

The only crew who were not at fault in any way were the DHL crew who were correctly following a TCAS RA to descend.

Orca strait

2nd Jul 2002, 21:42

The big sky theory just shrunk. With today’s technologically advanced navigation systems, aircraft can track laterally within meters of each other. Add in:
a fixed point (intersection)
Area ATC handover point
Multiple language accents operating in a common language
Expanded frequency digits (i.e. 123.245 MHz)
A crew that was quite likely not familiar with that particular chunk of airspace
Aircraft that were manufactured and equipped under different philosophical and regulatory requirements
And you have the proverbial chain of events that lead to a catastrophic conclusion.

Condolences to all...

foo fighting

2nd Jul 2002, 21:48

atco point of view

to those involved who saw the unthinkable on the screen in front of them only the greatest support.

caba

2nd Jul 2002, 21:59

The ATCOs involved are what I am thinking about,too. I won´t be able to sleep tonight...keep seeing coasted targets disappear and getting no answers anymore...

Hope that we will all (also management) learn from it...

Yaw String

2nd Jul 2002, 22:04

Two years ago I posted on the limitations of TCAS or more importantly, our correct response to its request. I will include this story again whilst making no judgement on either of the two crews involved. It is an indication of the predicament within which we could all find ourselves.
22nd. July, 1999. Azores airspace near UTEM FL370. Early morning, after sunup.
Taking rest in LH seat with co-pilot flying. Map range unfortunately left in 160 mile range(don,t do this guys).
Awoken by co-pilot to be told that an aircraft, seen on tcas to have been cruising 1000ft. below,on closing heading, was now climbing to our level. Shortly after focusing my eyes we received the TA then "descend" RA. In my case my forward vision was blocked by visors placed to stop my co-pilot being blinded by the rising sun. on the strength of the TCAS alert I obeyed the collision avoidance command to descend, with a map range of 160 miles.
Unfortunately the other aircraft having realised that all was not correct seems to have also descended, probably initiating his descent a fraction of a second before his TCAS had told him to climb. So there we were, Boeing 767 & Airbus A340 both diving for the same bit of airspace!!!! So that is how easily it can happen.
We are advised to aquire the conflicting traffic visually at the intial TA alert but we wait for our TCAS to tell us what to do if no visual siting is possible. Now what happens if only one of the two aircraft sees the other. Does he wait for TCAS to sort things out,& if he reacts according to logic how can he be sure the timing will be correct & will not end up contradicting an RA recovery manoeuvre! In my case my No. 2 did see that the Airbus was not going to hit us but kept quite at that point to avoid any confusion.

Be aware of the limitations of the current TCAS system & its interface with you & me.

I repeat, no pre-judgement of either crew intended.

Pilot Pete

2nd Jul 2002, 22:06

Very sad indeed

I have just watched the evening news (BBC & ITN and GRANADA as the DHL captain appears to be from Liverpool). Overall it appeared not a bad attempt from the BBC and ITN to put across what they thought they knew. Granada was worse telling how the DHL tried to 'dip' below the Russian jet.

The worst aspect for me has to be the DHL spokesperson who did himself and his company no favours by blatantly accusing the Russian crew of failing to respond to the ATC commands. He, like us, has no idea what was happening in that cockpit at the time. It would appear likely that the crew were attempting to deal with conflicting information (TCAS vs ATC) and may have had any other number of distractions at the same time. The FDR's will give a better idea and I am shocked that someone from within the industry will speak out so vehemently without having the full picture to hand. Decorum would have been a much better angle for him to pursue.

PP

Avman

2nd Jul 2002, 22:18

Some twenty years or so ago a unit I then worked at experienced a very close call in the middle of the night with only two aircraft on the sector. Low traffic unfortunately can sometimes lead to low levels of concentration/alertness. Then again it is not unusual, again in low traffic situations, for some controllers to leave a level change to two minutes prior, with a 2000 fpm rate - giving more than sufficient time when 1000 feet is all that's needed. In this particular case it appears (from official statements) that it was less than two minutes. Perhaps indeed the Tu-154 crew were just in the process of initiating the descent when their TCAS ordered "CLIMB". Possible hesitation........followed by the controllers repeated calls to descend may (speculation) have sadly misguided them into ignoring their TCAS. No doubt, as is so often the case with accidents, it will not come down to a single contributary cause. And no doubt when the final report emerges there will be lessons to be learned by both ATCOs and Aircrews alike.

foxmoth

2nd Jul 2002, 22:29

RRamjet
I agree it is easier to see at night if you have the lights down, but this is no use if the dark FD environment puts the crew to sleep!
Please remember TCAS is an AID to collision avoidance, and only that, ATC is first line, TCAS helps second line (visual sighting), and itis only when these 2 fail that you should be relying solely on TCAS - then you have little other choice. Having said that, if you get a TCAS RA with non of the fisrt two options giving an input (ATC telling you where the traffic is, and/or you seeing it), you MUST respond, which appears to be what DHL did!
Just an additional note. With TCAS that I have flown, in addition to the call, you also have a display, so if either crew was not certain which way to go (ie. TU154 having descend from ATC and climb from TCAS) they SHOULD have been able to see from the display what the other A/C was doing vertically even if they could not see it visually.

RIP

Capt Pit Bull

2nd Jul 2002, 22:32

Yaw String,

Why are you advised to try and get visual contact with the intruder?

It is not so that you can assess whether TCAS's RA is suitable or not.

You can not make that decision based on a visual spot - due to the difficulty in assessing relative altitude at high level (the horizon not being the same as the local horizontal).

The point of using a TA to get a visual spot is so that you can apply the normal rules of the air and Turn for collision avoidance.

TCAS is a good system, but not foolproof. Ultimately, if the other aircraft matchs your vertical manouevres, it will intersect with you vertically.

Fortunately, even if this happens, there is usually some lateral separation so instead of a collision an airprox results.

You want to miss the other guy. You can do that vertically or horizontally. Both would be nice, either is sufficient.

So, Fly the RA. This gives a very good chance of safety. Ignoring the RA is a 'Bad Idea' (tm).

But to cover the small possibility of system failure or the other aircraft manoeuvering opposite to its RA, supplement TCASs vertical RA with a Turn, either based on visual spotting or if offered by ATC.

So, to answer your scenario, if only one aircraft sees the other, a turn can save the day even if the RAs are compromised by incorrect pilot vertical response.

CPB

HOVIS

2nd Jul 2002, 22:35

Please don't take this the wrong way but does the right hand rule of the air still apply?

IE. If head to head then break right, or the a/c that has the other on the right shall give way.

I remember this from my gliding days years ago, but does it apply to airliners?
I don't fly powered a/c so don't have a go and tell me that I should know this.

Obviously it is a moot point in this case but I thought I would ask.

caba

2nd Jul 2002, 22:47

The right hand rule of the air applies to VFR only...

Alpha Leader

2nd Jul 2002, 23:02

The following compiled from AP and SDA releases:

The Swiss air traffic controller on duty gave the crew of the Russian TU-154 aircraft only 50 seconds’ warning prior to the eventual mid-air collision. Earlier reports this morning (Tuesday) had referred to 1 ½ minutes.

Swiss ATC company Skyguide’s manager Urs Ryf confirmed that details released by German crash investigators about the timeline involved in the mid-air collision were correct. Accordingly, ATC instructions to reduce altitude were issued about 50 seconds prior to the collision. This morning (Tuesday) Skyguide had still maintained these had been issued up to two minutes earlier.

A second set of instructions was issued 25 seconds prior to the collision, as the Russian pilot had not reacted to the first advice. Ryf was not able to positively confirm whether a total of two or three sets of instructions had been issued by the controller to the Russian crew. “There were a couple of sets of instructions” he said. Skyguide, at this moment, is also adamant that the instructions were issued in a tight timeframe, but not too late. “All else has to be determined by the ongoing investigation” Ryf said.

A Swissair pilot with years of experience, Ruedi Bornhauser, said on a Swiss radio news broadcast that 50 seconds were by far sufficient notice to avoid a mid-air collision. In principle, he said, even 25 seconds would be time enough.

However, it is still unclear what type of collision avoidance system – if any - was fitted to the TU-154. Under normal circumstances, such a system would give its crew about 40 seconds’ warning. “And it would be only 25 seconds before the system would instruct to climb or dive” said Bornhauser.

It remains to be explained why ATC did not instruct the TU-154 crew to descend much earlier. Anton Maag, the Area Control Centre manager, commented that Swiss air space was very tight and that the work cadence of controllers on night duty was the same as during the day, despite there being fewer flights at night. This could be the reason why the controller on duty issued his instructions when he did. “He will have to comment on this point” says Jean Overney, Head of the Swiss air accident investigation bureau.

Skyguide also revealed that at the time of the mid-air collision at 23.35.40, the second controller on duty that night had been taking a break. At this point in time, there were another three planes within the Skyguide air space but 30 to 40 nm away from the collision site.

Skyguide were also in contact with the crew of the B-757, and had been so since that aircraft had entered Skyguide’s air space over the Swiss-Italian border. The pilot of the B-757 also informed ATC that he was following instructions of his TCAS to descend. This report from the Boeing crew was received immediately prior to the last set of instructions radioed to the TU-154 to descend, after which the collision happened.

foxmoth

2nd Jul 2002, 23:02

In a collision situation it STILL makes sense to apply the RH rule, you then BOTH know which way you need to turn, and you BOTH turn out of each others way rather than one turning right and the other turning left

whats_it_doing_now?

2nd Jul 2002, 23:04

There seems to be a lot of speculation as to why this happened, and the media are firmly pointing the finger of blame at the russian pilot. Did you read the Evening Standard? Judge jury and executioner springs to mind.

It appears to me that what has happened is similar to many other aviation incidents in that there was a combination of situations that coincided to create a fatal outcome. On its own, any of the circumstances may have passed without major problems, but it was the combination + bad timing multiplied by a great deal of bad luck.

I do hope this proves to be the case, however even if that happens, I doubt the media will be publishing appologies for pointing the finger of blame so prematurely in the future. They will get away with bloody rotten journalism - again.

:( :mad:

Devils Advocate

2nd Jul 2002, 23:10

Of course whilst this might not be an issue in this case (other than being at FL360 in apparently clear skies) ... but just how many times have I / you / we seen flight decks at night that are nicely illuminated by their 'Dome Light' ?

Of course whilst it's certainly handy being able to see to do the 'Times Crossword' etc., it's not so good for the old 'night vision' & Cones & Rods - e.g. anybody care to remind us of how long it takes for the human eye to become attuned to seeing in / into the dark ?

Now there's an awful lot to be said for Mark1 Eyeball - and indeed that's some of the reason why our AME's test them for us every six months as part of our Class 1 Medical renewals.

So on the basis that first and foremost we're meant to be 'professional aviators' - sod the crossword, let’s stop any complacency, get them cockpit lights off at night, start looking outside the bloody windows, and basically let's do what we're being paid to - namely aviate in a professional manner !

Of course there's always the alternative, i.e. "Don't worry, it'll never happen to us - after all we're on radar and we've got TCAS"

Yeah, right !

Ps. Sorry for the rant / lecture but when children are killed it (rather obviously) really REALLY makes me :mad: !

PPs. And before anybody ‘flames’ me, I’m not suggesting that this is what happened in this case but, more over and in any event, we owe it to our innocent charges to act according to our status as professional pilots – i.e. if your kids were on that (or any other) flight, just what would you expect the of the pilots (and controllers) ?

Backoffice

2nd Jul 2002, 23:40

Sorry to say this, if it hasn’t already been said (there are 11 pages to this thread), but I feel there is another culprit here…..Advance planning.
Now, I’m not over familiar with slot management, so please correct me if I’m totally off track, but this was European airspace, or part of the Eurocontrol area.
Slots have to be approved through airspace.
How then, at 2330 are two aircraft flight planned through the same sector at the same level, when logic suggests planning them at a different level, if nothing else, to avoid controller intervention.
Assuming the German ATC do not have a crystal ball to say what aircraft are where in Swiss airspace, when they hand-over to Swiss ATC, aren’t EuroControl a little responsible for allowing conflicting plans in the first place.
Reading these pages I’m saddened that I have to hear the pitfalls of TCAS from first hand experiences of others following such a tragic accident. Funny how the sales blurbs never mention these things.
My heartfelt condolences to the families who have lost their treasured one’s.

Fox3snapshot

2nd Jul 2002, 23:44

Also posted in ATC issues......

To much reliance on "gadgets and Gizmo's", lets get back to raw ATC and flight operations and also use some of the more basic, and yet effective ATC tools at hand. Radar is wonderful, but at the end of the day the triple redundant radars (as always so proudly advertised by manufacturers!!!) do fail, ours only 2 days ago..... my point is that it is still important not to forget the basics of our procedural standards and build a bit of "fat" into the program to allow for, poor comms, possible language problems, co-ordination failures, radar failures etc. It should be noted that quite a few of these issues are human factor related and on last check we are all human.

I am sure for the controllers that have been in the business long enough and have filled their "little bag of tricks", that one of the most dangerous times is when it is quiet. Having had a few good scares on these grounds, I ensure now that during these times I am proactive with conflict resolution because I have let myself down before through complacency. This point is made not necessarily to the actual case at hand, which investigation is still only in its infancy, but more as a wake up call to us all in every aspect of the industry to ensure we all maintain our highest possible standards and support each other to provide the best and safest service possible.

It goes without saying that regardless of who is responsible, the controllers and supervisors at this centre will be enduring the most horrific time of the lives and it is important we make sure that we give them the support they need.

:(

Brookmans Park

2nd Jul 2002, 23:56

ARE RUSSIAN ALTIMETERS CALIBRATED IN FEET OR METERS?

Alpha Leader

3rd Jul 2002, 00:01

Anton Maag, Skyguide’s Area Control Centre manager, conceded on Swiss TV’s “10 vor 10” news programme Tuesday night that the ATC in-house collision warning system had been inactive on the night of the mid-air collision. All controllers had been informed of this, as the system was down for maintenance – work which could only be carried out during hours with marginal traffic.

Backoffice

3rd Jul 2002, 00:13

U/S equipment, hmmm, sounds like the ground movement radar at Linate. Or is that too caustic ?

GotTheTshirt

3rd Jul 2002, 00:44

Throughout the preceeding pages much discussion has centered around TCAS and the various configurations.
Perhaps I have missed it, but it costs $250,000 to install the "mandatory" Mop 7 TCAS ( from scratch) to meet current EU (JAR ) requirements, so are aircraft flying in EU airspace that do not meet these requirements ?? If so how?

BIK_116.80

3rd Jul 2002, 01:07

Alpha Leader posted 2nd July 2002 10:07

“Anton Maag, Chief of Zurich-Kloten Control Tower, and Skyguide Spokesman Patrick Herr, held a press conference today, Tuesday, to review the events of the previous night.

Between 2300 and 2400, there were no unusual occurences in Swiss air control space, with only a few aircraft in the air. Swiss ATC was handed over the Russian TU-154, which was on a East-to-West routing by German ATC at around 2330, whilst the B-757 freighter, on a South-to-North routing, was handed over by Italian ATC to Swiss ATC at 2323. Both planes were at an altitude of 36000 feet (around 11500 meters).”

Alpha Leader posted 2nd July 2002 11:55

“According to Anton Maag, Manager of Skyguide’s Area Control Centre, speaking at a media conference held on Tuesday morning at Zurich Airport, the situation until immediately prior to the mid-air collision had been entirely normal. Given the time of night, few aircraft were in the sky.

…Between 8 and 10 nm (or approx. 1 ½ minutes of flight time) prior to the crossing point ATC instructed the TU-154 crew to initiate a descent – but this instruction was not confirmed. A second identical advice also remained unacknowledged. It was only on the third attempt that the TU-154 crew reacted and began to seek the assigned, lower flight level.

…The TU-154 approaching from the east had been handed over by German ATC to its Swiss counterpart...at 2330. The flight had been advised in a timely fashion, too. The B-757 freighter had crossed the Italian-Swiss border (to the south of the collision site) at around 2300.

At the time of the actual collision, there was very light air traffic, with only a few aircraft in the sky. The two controllers on duty in Zurich had only one sector to look after.”

Volume posted 2nd July 2002 12:49

“On July 1st 2002, 23:35 MESZ (21:35 UTC), well above the Bodensee a midair collision happened...

(Analyzing swiss radio recording, the 154 was advised to sink from FL360 to FL 350 50 seconds prior to the collision…”

Alpha Leader posted 2nd July 2002 23:02

“Swiss ATC company Skyguide’s manager Urs Ryf confirmed that details released by German crash investigators about the timeline involved in the mid-air collision were correct. Accordingly, ATC instructions to reduce altitude were issued about 50 seconds prior to the collision. This morning (Tuesday) Skyguide had still maintained these had been issued up to two minutes earlier.

Skyguide also revealed that at the time of the mid-air collision at 23.35.40, the second controller on duty that night had been taking a break. At this point in time, there were another three planes within the Skyguide air space but 30 to 40 nm away from the collision site.”

Time Line

23:00 or
23:23 B757 handed over to Swiss ATC.

23:30 TU-154 handed over to Swiss ATC.

23:34:10 or
23:34:50 First instruction to TU-154 to descend.

23:35:15 Further instruction to TU-154 to descend.

23:35:40 Aircraft collide.
(times based on above reports)

What was the Swiss air traffic controller doing for the four minutes between 23:30 and 23:34:10 (or 23:34:50)?

We all know that just because an ATCO is not transmitting it does not mean that they are not busy.

The Swiss air traffic controller must have been engaged in activities that were of such a pressing nature that they were of a higher priority than keeping the planes apart.

Whilst I can well imagine that the air traffic controller is experiencing a great deal of distress, I am finding it difficult to summon compassion because of the apparent likelihood that this distress has been largely self-induced.

The controller might be emotionally distressed, but the pilots and their passengers are dead.

May they rest in peace.

Rhoo

3rd Jul 2002, 01:25

Often wondered about this and I am sure someone here can explain.

How does TCAS deal with an aircraft that is not actually at the FL at which it is reporting to be, due to 1013 not being set at transition?

From my understanding ATC and other aircraft TCAS equipment would observe it to be at the correct FL. The whole time the aircraft could be off the actual FL by the difference between 1013 and QNH which is sometimes quite significant and in extreme cases could be well over 500’ .
I appreciate that TCAS can derive azimuth and distance without any need of altitude input but wondered how it would deal with an apparent conflict where the aircraft were actually vertically separated but appeared to be at the same level and in conflict due to incorrectly set altimeters in one aircraft? Could it give a Descend RA to one aircraft to vacate the apparently common level while in fact descending it towards the other? Or is it "smart" enough to take care of this sort of situation?

I am sure someone can put me straight on this one.

Wizofoz

3rd Jul 2002, 01:44

I stand to be corrected, but I believe the TXP and therefore the TCAS get Barro information direct from the ADC. Therefore what is tramsmitted is raw pressure altitude and ATC correct this for QNH when the aircraft is below transition level. Therefore both TCAS units are using the same Datum regardless of subscale setting.

There was a very near-miss in Japan recently when an aircraft followed an incorrect ATC direction instead of a TCAS RA. TCAS is a wonderful tool IF crews are trained to follow RAs as a first action.

BIK_116.80

3rd Jul 2002, 01:51

The altimeter setting has no effect on the transponder's mode C output or TCAS which are always referenced to standard pressure of 1013/29.92.

Rhoo

3rd Jul 2002, 02:56

Wizofoz and BIK_116.80 that makes good sense and answers my questions nicely, Thnx.

Wino

3rd Jul 2002, 03:36

The descent calls to the Russian plane were late. They were SO late that DHL had already called their own RA that they were maneuvering for.

I suspect that part of the delay was that the Russians were being told to climb by their TCAS and decend by ATC. If that was the case and stuck with that choice, they chose badly.

ALWAYS follow the RA. The controller is NOT in the loop of the negotiations between the two aircraft carrying out the avoidance maneuver and doesn't know who has been told to climb and who has been told to descend by the respective TCAS systems. DO MAKE A TURN if given by the controllers, but DO NOT allow the controller to overide the TCAS instructions as to climbing, decending, increase climb, maintain climb, etc...

A suprising number of people don't know that...

(wildass speculation begins)Furthermore, that 154 looks like a 727, and probably can come down like a bag of hammers just like a 727 (IOW a much greater descent rate is possible from the 154) and so even though DHL might have started down first, the 154 could have caught it...(Wildass speculation stopped)

CHeers
Wino

Fox3snapshot

3rd Jul 2002, 03:38

Bindook,

I assume you are referring to the settings above the transition layer?????

:rolleyes:

Alpha Leader

3rd Jul 2002, 03:48

The following compiled from info in the public domain:

Skyguide is a company commissioned by the Swiss government to handle ATC in Swiss air space. To the extent of 99.85%, its shares are held by the Swiss Confederation. (This means it is not a statutory body, but - in the eyes of the law - a privately held company). Headquartered in Geneva, Skyguide has been responsible since early 2001 for both civil and military ATC – a unique consolidation of duties in Europe. Some 1400 employees control commercial and military air traffic at Zurich-Kloten, Geneva-Cointrin, Bern-Belp and Lugano-Agno as well as at various military air bases. Skyguide also controls assigned air space over foreign territories (such as over Southwest Germany, where the recent mid-air collision took place). Skyguide’s authority over that particular German sector has been the subject of controversy in the context of the Swiss-German air agreement, as the German side has threatened to re-assign this area to German ATC by way of decree should the current round of negotiations for a new air agreement prove unsuccessful.

The Swiss government recently commissioned a study to look into a permanent ATC system which would also identify aircraft without transponders.

Skyguide’s role has been a regular focus of recent air crash investigations, such as the Crossair crash of 24 November 2001. In the case of the Alitalia crash of 14 November 1990, in which all 46 passengers and crew were killed when their aircraft flew into Stadlerberg, a hill located north of Zurich airport, the final accident report listed nine contributing factors, one being the failure of the assigned air traffic controller to provide a timely warning which could have prevented the crash. However, a criminal investigation was eventually discontinued, and faced with compensation claims, the Federal Court later ruled out any responsibility by air traffic control.

shakespeare

3rd Jul 2002, 04:20

I 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. I will wait for all the facts, however far too many pilots fly at or request non-standard cruising levels, without too much thought (if any) of opposite direction traffic. They implicitly trust ATC to tell them if a collision risk exists.

All those innocent people (and wonderfully talented children) killed in an accident which could have possibly been avoided by adherrance to basic rules.

Alpha Leader

3rd Jul 2002, 05:23

Swiss news agency SDA reports that the flight data recorder of the B-757 has been recovered.

Yesterday, the flight data recorder of the TU-154 and a CVR - believed to be that of the same a/c - had already been found.

NigelOnDraft

3rd Jul 2002, 05:34

There was a comment a few pages back, from an ATCO (?) about proposed SOPs now aircraft have TCAS. It was along the lines of "get lateral separation - let TCAS sort them vertically" when aircraft are getting close.

This seems excellent advice - and would apply to us pilots also. Use the TA to try and acquire the likely "traffic" target - prepare for RA, and plan a LATERAL avoidance maneouvre if necessary. Whatever you do, when you get the RA, follow it religously, not just in direction, but 'green sector' RoC/D / attitude.

We are experiencing a "problem" (others?) with the latest TCAS software, where not all "targets" are being displayed on the screen. We have been repeatedly assured that the target not on the screen IS being monitored by TCAS, and will give TAs/RAs. Therefore visible acquisistion is not a guarantee you have the correct traffic...

Swiss ATC - it is fine to say "an error" of theirs to call the descent so late (and I agree it seems the largest factor to date) - but what are the rules? You cannot "blame" someone unless there is a limit they broke... I was reassured by the (UK?) ATCO who stated that he considered he had failed if the aircraft had not "achieved 1000' separation by 20NM". Given, for a 1000' descent an average descent rate of 500' or less, he was never going to have 1000' separation by 5NM. I really hope his intial call to the Russian was prefixed with an urgency attention getter.

Finally, although it is good advice to "keep the lights turned down" etc, I doubt it would have altered anything here vertically - even if one/both aircraft FD lights were "up". It is very difficult to judge relative altitudes by day, let alone night, and I believe there was a mid air in the USA (near NY?) (1 ac a Constellation?) where correctly separated aircraft collided because they visually felt a collision would occur, and one climbed / descended into the other (sloping cloud I think).

Lessons to me - let TCAS look after the vertical, I'll try and help laterally, and I would hope ATCOs would consider likewise when standard distances of achieving vertical separation (well before TCAS would act) have been missed...

NoD

Nugget90

3rd Jul 2002, 05:39

WINO addressed TCAS II training: what pilots should be trained to do - and what they must not do - are described in Flight Deck Forums >> Tech Log >> TCAS.

Ausatco

3rd Jul 2002, 05:59

BIK_116.80 wrote

What was the Swiss air traffic controller doing for the four minutes between 23:30 and 23:34:10 (or 23:34:50)?

We all know that just because an ATCO is not transmitting it does not mean that they are not busy.

The Swiss air traffic controller must have been engaged in activities that were of such a pressing nature that they were of a higher priority than keeping the planes apart.

Why not wait for the FACTS to come out before leaping to conclusions. :mad: Your armchair analysis is constructed of a number of reports of what other people have had reported to them. Some of them are media releases. Hardly definitive.

Whilst I can well imagine that the air traffic controller is experiencing a great deal of distress, I am finding it difficult to summon compassion because of the apparent likelihood that this distress has been largely self-induced.

The controller might be emotionally distressed, but the pilots and their passengers are dead.

Your cynicism is stunning.

This is a forum of professionals. Try and be one, there's a good chap.:mad:

AA

BEagle

3rd Jul 2002, 06:12

I do not intend to pass comment whilst the facts are still emerging. However, one observation I do have is that it is almost impossible in these RVSM days to know whether the FL you've been assigned is 'wrong way' or not. Gone, it seems, are the days of flying IFR semi-circulars based upon track in Class A airspace.

arcniz

3rd Jul 2002, 06:26

This tragic accident seems to be characterized by a short list of ambiguities that were either unresolved in time or unsatisfactorily resolved. Perhaps readers will care to correct, amend or add to this list.

One can hope that it may be possible in the future to define or refine procedural and technical means to eliminate these and similar ambiguities to prevent a recurrence.

Ambiguity 1) Relative Position: The two aircraft seem to have been unaware of each other's positions, especially the details of same altitude and intersecting course, until and even after the TCAS alerts. So the crews were not prepped for informed avoiding action there and then in the dark night.

Ambiguity 2) Visual: The roughly right-angle intersection of aircraft tracks made visual contact a somewhat difficult scan at night until very close to the collision zone. Other than the assumption of common frequency guarding, I have not seen info that traffic advisories were called to either aircraft about the other.

Ambiguity 3) Timing: The flight crews evidently had no particular sense of urgency until at or near the time their respective TCAS alerts sounded.

Ambiguity 4) Resolution: The presumptively reliable TCAS information for DHL was unambiguous but turned out to be unhelpful. TCAS guidance in the TU is not yet as clearly understood, but by inference that it was opposite to DHL guidance, so it would also have been opposite to contemporaneous ATC guidance, creating a fundamental and unresolvable ambiguity for the TU crew at the critical decision moment.

Ambiguity 5) Remediation: In the last 25 seconds prior to the collision, none of the responsible parties (DHL, TU, and ATC) evidently had sufficient information to call off the disaster because information ambiguity existed at all three points of control regarding the T-25 manoeuvers and merging positions of the two aircraft.

Semaphore Sam

3rd Jul 2002, 06:35

Following questions are just that; not in any sense implied judgment:

1. ARE THE RUSSIAN ALTIMETERS IN METERS OR FEET? (5th time?)

2. Do Russians still use radio operators (as was the case with the Delhi collision a few years ago) that 'translate' radio calls to non-English speaking pilots?

3. Granting tremendous improvement in Russian English; with the new RVSM flight levels (FL 360, 340, etc) possibly causing delay in understanding due to newness of numbers, AND having to translate these numbers to meters (again new numbers), AND possibly having to go thru a radio operator/translator, the possibility for delay in understanding & compliance is there. Combined with a late call by ATC for a descent, a possible chain exists. Again I say POSSIBLE; just speculation.

4. (6th time) DO RUSSIAN ALTIMETERS USE METERS OR FEET?

Fox3snapshot

3rd Jul 2002, 06:59

AusATCO,

I am with you....bit my tongue but happy to see I am not the lone soldier.

Bindook was a little out of line...Bindook do you have access to the actual ATC/Pilot transcripts, radar tapes, CVR, Aircraft Despatch notes, WX info, blah-de blah-blah....and if the answer to any one of these questions is no.... then Bindook I am sorry you do not even remotely come close to being able to determine who is at fault and you can join the ranks of most of the speculating community until this is all officially released.

I have just as many (if not more) mates in the flight deck environment than the ATC environment, but ultimately for many years have enjoyed something in common with all......we are in the aviation industry!!!!!!! Therefore lets not bleat and complain about who should do what and when and who's fault it is, but get together (a big narly booze up would do it!) and resolve decades of unsolved issues!

There will be a chain of errors in this disaster, and remember on a daily basis any one of us could be a link in this chain....

Good better best,
Never let it rest,
Till the good is better,
And the better best!

Alpha Leader

3rd Jul 2002, 07:12

Semaphore Sam:

Traditionally, Russian a/c have had altimeters with indications in meters. I understand that the TU-154 involved in this mid-air collision was equipped with one, too.

TopBunk

3rd Jul 2002, 07:24

Not trying to prejudge anything, but I had a similar incident in mid-1995 in the region of the German/Swiss frontier whist en-route from LGW_SOF.

We were at FL330 SE bound working Munich about 80nm NW of RTT NDB (if I recall correctly), when we got an instruction from Munich ATC to climb immediately to FL350 and turn left 50 degrees.

This was in a pre-TCAS 737-200.

The intruder was a Dassault Falcon jet westbound under Zurich control at FL330. It passed within about 1nm horixontally and about 800ft underneath as we climbed.

I believe that it was to be investigated by the German authorities, maybe someone can find the results and point to them (date of event 15/6/1995).

Condolences to all involved, there but for the grace of God...

TopBunk

Ruslan

3rd Jul 2002, 07:32

To whose who seeking whenever altimeter in feet or meters

I’ve posted already, Tu 154 equipped with BOTH, further more this is absolutely NO FACTOR,
Check EUROCONTROL RELASE showing height monitoring status of Russian aircraft 1 HOUR before tragedy

Gathering all available information, I would admit we came close to what happened, considering extra (instructor) captain onboard of RA-65816

Bigmouth

3rd Jul 2002, 07:37

Was it VMC or IMC at FL350?

Standard_Departure

3rd Jul 2002, 07:42

Skyguide claims that it is within standard operating procedures to issue an instruction to achieve separation within 50 seconds of impact.....

If this is the case, we can expect that the first instruction issued to the T154 would NOT have included the words "Traffic Avoidance", "For avoiding action" or "immediately", and that the ATC would have transmitted the instructions in a cool calm and collected fashion......

What will skyguide say if these words are in fact spoken in the transmission.

Fox3snapshot

3rd Jul 2002, 07:53

Lets talk about the altimeters, understand that the jets were both originally cruising at the same level (verified), regardless of what measuring system they were using!, the requested level change from ATC was minimal ie 1000'...enough to provide vertical sep. Under the new RVSM criteria if it was in fact being applied. Regardless of peoples perception and misunderstanding of the new RVSM standards this collision could have been at any flight level ie. below FL290 and the 1000' separation standard required would would still be acceptable regardless of where you are in the world.

The Tupolov operators were experienced crew and the flight level change (feet or meters!) was not a major issue. It should be noted here, for those not familiar, that most the modern jets are equipped with altimeters and/or squizzy LCD/analogue kit that represents both standards meters/feet, why you ask?? Well it isn't just the Russian/Baltic states that are doing business in these numbers, China also are still working in this format and the Cathay/Air Honkers/Dragonair lads and ladettes will be very familiar with this, and is it now a good time to mention the Americans still deal with Altimeter readings in Inches instead of Hpa/Mba,

When......oh when will this planet decide on a universal standard!!!!

List of Aviation measures...
Height in feet....ooooh ...and meters
Visibility in .....meters/Km
Area pressures...Hpa/Mba...and Inches...
Longitudal/lateral ATC Separation....in miles
Time....GMT/UTC
Runway separation....meters...and feet etc. etc. etc.

:mad:

ramsrc

3rd Jul 2002, 07:54

Further to what Ruslan has said about dual altimeters on the Tu-154. This photo (http://www.airliners.net/open.file/209564/L/) from airliners.net shows them quite clearly on a Malev Tu-154.

sponix

3rd Jul 2002, 07:56

CPB

"The incidents you list above, whilst certainly part of the communities TCAS learning process, are somewhat dated. To the best of my knowledge the issues raised have been addressed."

I hope the problems have been sorted! Can anyone be sure though and have *all* existing systems been updated??

"..So for erroneous altitude encoding to nail you, both ADCs have got to be in error by the same ammount, and become so at the same time. Highly unlikely."

Unlikely but *possible*.

"As mentioned above, it appears the b757 manouevred first. From reports above, and the crews call to ATC, a descent was flown."

The impression I got from the media was that the Tupolev strated to descend shortly BEFORE the Boeing.

"Someone else maintains that the t154 was also TCAS equipped."

Yes, BBC news stated that BOTH planes had TCAS.

"If if it was equipped, (and on and serviceable), then they will have been receiving a 'Climb RA'. They descended. TCAS should still have been able to ressolve the situation by issuing a reversal to the b757 UNLESS it was pre version 7 (see my post above)."

Anyone know if Russian TCAS systems have been updated to the latest software?

"Now, pure speculation I admit, but lets say you are flying a non TCAS aircraft and you suddenly realise that ATC want you to descend urgently. As you commence your descent, you hear another aircraft saying 'TCAS Descent'. What goes through your mind?"

I don't like to think..

Sponix

Fox3snapshot

3rd Jul 2002, 08:00

Please check Ruslan's post to answer the altimitery questions:

Ruslan:

To whose who seeking whenever altimeter in feet or meters

I’ve posted already, Tu 154 equipped with BOTH, further more this is absolutely NO FACTOR,
Check EUROCONTROL RELASE showing height monitoring status of Russian aircraft 1 HOUR before tragedy

Gathering all available information, I would admit we came close to what happened, considering extra (instructor) captain onboard of RA-65816 Ruslan To whose who seeking whenever altimeter in feet or meters

Alpha Leader

3rd Jul 2002, 08:18

Based on official statements by Skyguide to date (and they are far from being unambiguous and complete), there are three major questions hovering:

Why were two a/c which entered Swiss-controlled air space on intersecting flight paths allowed to proceed for so long at identical flight levels?
In the case of the TU-154, the time elapsed since entering Skyguide’s air space was around 4 ½ minutes (based on Skyguide’s on press releases, and in the case of the B-757 it was 7 minutes.

Why did the Russian crew not respond to the first set of instructions?
In combing through statements released to date, there has also been no clear evidence as to whether the Russian crew ever positively acknowledged the second set of instructions (issued about 25 seconds prior to impact) – other than to initiate a descent.

What was going on at Skyguide’s Control Centre?
With their own conflict detection system down and only one controller on duty (the other taking a break), was there possibly a sudden case of task saturation (or the opposite – a false sense of “no problem”)? Apart from the two a/c that eventually collided, there were only another three a/c in the sector at the time. It has been confirmed that the B-757 crew radioed to Zurich ATC that they were diving based on their onboard TCAS, so – given his previous/simultaneous instructions to the TU-154 to descend, one would have expected the controller to immediately instruct the B-757 crew (with whom he was positively in contact) to climb.

We once again face the sad fact that an accident is rarely the result of one single action, but an unfortunate chain of events.

'%MAC'

3rd Jul 2002, 08:19

Wow, there’s a panel that could use a human factors engineer. I suppose the altimeters (3 of them visible in the photo) are clustered around the RMI? Which one is in feet and which in meters? Two are drum pointer types, and the odd one is the 3 hand pointer to the right of the RMI, but they don’t seem to be labeled.

ramsrc

3rd Jul 2002, 08:39

%MAC

This photo (http://www.airliners.net/open.file/012885/L/), again from airliners.net, shows a Tu-154 in flight. The two altimeters above the RMI appear to show feet (right hand instrument) and meters (left hand instrument). Not sure where the third one fits into the scheme of things though, perhaps provided as a backup unit?

Oldjet Jockey

3rd Jul 2002, 08:50

If the times quoted in previous posts are correct, I am amazed that a controller accepted the hand over of a flight on a crossing track at the same level as an aircraft already under his control when the time at crossing point was exactly the same and this only five to six minutes before the crossing point. Absolutely no longitudinal separation and very little time to resolve the confliction. Questions need to be asked on the application of co-ordination procedures between the various ATC units:confused:

'%MAC'

3rd Jul 2002, 08:53

Ramsrc

Thanks, that clears it all up. The 3rd looks like meters also.

(They're not exactly holding altitude)

Alpha Leader

3rd Jul 2002, 09:05

Oldjet Jockey:

Good point. In particular, the flight path of the TU-154 (heading for Geneva) was to take this a/c over Trasadingen (only about 10 - 15 nm W of the collision site), at which point it would have been directed to 35000 feet anyway, this being the standard FL for this route. The question is, indeed, why did ATC not direct this a/c to 35000 ft immediately at hand-over?

GEENY

3rd Jul 2002, 10:07

ID 90 and others,
In the Inex-adria vs Trident the DC-9 was alreadyabove the Trident level when instructed to descend.
If the TU was physically above the 757 the TCAS RA make sense (the altimiters could have been showing the same alt).

Oldjet Jockey

3rd Jul 2002, 10:28

Alpha Leader

You may be right about the level change requirement at trasadingen but my main point was that the TU154 should never have been accepted at FL360 in the first place with crossing traffic at the same level. Swiss ATC should have refused to accept it at that level and requested the German ATC to change its level before handover!!!!!!!

vanman

3rd Jul 2002, 11:17

Having waded through this entire thread I would add the following observations:-

1) I have flown extensively in and out of Swiss airspace from a multitude of directions and have never suffered any handover problems (other than an initial incorrect freq from the Italians maybe). The swiss have always acted with a high standard of professionalism. Lets give them (as with all the other parties) the benefit of the doubt until the facts appear.

2) I have yet to see evidence, from any official source, that the TU154 was indeed TCAS equipped although I believe that it is a requirement to fly in European airspace. Having said that I have flown an aircraft over the same point within the past two months with a large ADD sticker next to the transponder relating to the unserviceability of the TCAS system. The MEL provides 7 days for it to be rectified.

3) It would seem that this accident may be attributable to, for whatever reason, the instructions to the TU154 to descend coming too late so that, by the time they were translated into action in the cockpit of the TU154, those instructions were in conflict with the instructions from the TCAS. This leads a pilot into a situation where seconds are vital but indecision or even an incorrect response are possible (especially in a quiet sky late at night).

I would argue medium range collision avoidance by controllers can and should involve level changes (ie would have been applicable on first contact with both these aircraft). Once normal seperation has been erroded, and given the likely onset of conflicting Resolution Advisory messages from the TCAS units, that for a controller to offer anything other than a lateral conflict resolution call would be extremely dangerous for the reasons which may have become all too evident in this case.

Simple let TCAS take care of the vertical - limit the controllers inputs to the horizontal - no conflicting instructions can be received.

Sympathy to all involved.

sky9

3rd Jul 2002, 11:19

A report in the BBC midday news suggested that the Swiss ATC conflict alert was turned off for maintenance.

Boulderman

3rd Jul 2002, 11:19

i accept that these a/c were not flying at their max alt, but I was wondering if a 'TCAS expert' could answer this question. If 2 a/c at say 42000 on an intercept course with resulting TA followed by RA would one a/c be given a command to climb? and would this be wise to accept if it took the a/c above its max operating altitude and close to 'coffin corner'.

Or does the system take into account a/c performance when commanding an RA? If flying at high altitudes would TCAS command one a/c to descend and another to maintain its level?

Alpha Leader

3rd Jul 2002, 11:24

Oldjet Jockey:

Your point fully taken. I am not too familiar with (Swiss) civilian ATC (only military ATC), but I would doubt whether you could refuse a handover once the a/c has physically entered your sector.

Alpha Leader

3rd Jul 2002, 11:38

Immediately prior to the mid-air collision over Lake Constance there was – contrary to earlier reports – a breach of duty at Skyguide, the Swiss ATC company. One of the two duty controllers had left his post contrary to standing orders.

The second controller of Swiss ATC company Skyguide who had taken a break at the time of the mid-air collision over Lake Constance had left his workplace at Zurich Airport control tower without authorization. This account of events was conceded by Skyguide manager Anton Maag during an interview on Wednesday morning.

Internal regulations stipulate that during maintenance work on the in-house conflict warning system installed at Skyguide, there must be two controllers on duty at all times. “The violation of this directive will have internal consequences for our entire operations” said Maag. “We must ensure that current regulations are followed more accurately” he added.

In this interview, he did not exclude that the absence of the second controller might have contributed to the collision of the two aircraft. This, however, would have to be a matter for the ongoing investigation, he added.

The above based on AP at 1237 MEZ

120.4

3rd Jul 2002, 11:41

Even if the STCA was turned off, isn't that only a last safety net?

I really feel for the Russians. Sure, they could probably have prevented the collision and the STCA would probably have done too, but how was the confliction set up in the first place?

It is a REGULAR occurance for traffic to miss r/t calls, sometimes it takes 3 or 4 attempts to get a response. At Heathrow yesterday a shuttle was out of contact for several minutes; they were about to scramble the Tornados. A few years ago traffic off BNN and LAM on conflicting tracks very nearly took each other out because BOTH were off the r/t for several minutes. If we are expecting things not to go wrong then we are being naive in the extreme and if we are building systems on that basis so that we can move more traffic then we are in for more of this.

I feel sick.

Point 4
:(

Avius

3rd Jul 2002, 11:43

Boulderman,

your eveluation is correct. The TCAS in deed does include the performance-factors of the aircraft, and in 42000 feet (assuming that is close to the max. altitude under given conditions -A/C weight, Temp., etc.), the TCAS would not issue a climb-command on RA, but as you correcly stated, to maintain the present altitude, while the other A/C is commanded to descend.

Of course, a Learjet operating at 42.000 feet is likely to receive a climb command on RA, while a 747 will certainly be commanded to either maintain altitude or to descent by the TCAS.

Cheers

captchunder

3rd Jul 2002, 11:52

Bring on CPDLC

GLADTOBEONE

3rd Jul 2002, 11:56

Just an observation but on the front cover of the flight safety publication issue 47 the aircraft in the back ground appears to be Reg. 00 DL-K.

:(

I would only add that it is a very sad event and shall await the formal report to make any conclusions

Alpha Leader

3rd Jul 2002, 12:05

From an interview with Volker Thomalla, Editor-in-Chief of "Flug Revue", published today via Süddeutsche Zeitung/AFP/dpa:

Swiss AT controllers did not work "to their optimum capabilites" in the minutes immediately leading up to the fatal mid-air collision, according to Volker Thomalla, Editor-in-Chief of "Flug Revue". Their instructions to the TU-154 crew had been issued at very short notice, he said. There was no apparent reason for the controller to issue his warning a mere 50 seconds prior to the projected collision point, but he should have done so considerably earlier. On the other hand, AT controllers should normally be able to rely on cockpit crews reacting promptly.

He also added that Swiss ATC "did not have a very good year in 2001", with some 55 near misses recorded. This had to be seen against a background of very heavy traffic on intersecting air routes, as North-South and East-West routes crossed over their air space. A unified European air space as well as a single standard would contribute towards greater safety, he added.

sponix

3rd Jul 2002, 12:12

It seems as though the early warning systems had been switched off by Swiss ATC to test the software, shortly before the crash:

(From: ananova.com, bits snipped )

An automatic warning system alerting controllers that two planes were on a collision course was switched off when they crashed above Germany.

A Swiss air traffic control spokesman said the warning system was switched off for maintenance, and it was "a purely theoretical question" whether the system alone could have prevented the disaster.

"Many signs point to an exceptionally unlucky combination of circumstances," Patrick Herr said.

The spokesman said the warning system was undergoing software checks. The routine maintenance is carried out at quiet air traffic times, he said.

Story filed: 11:24 Wednesday 3rd July 2002

http://www.ananova.com/news/story/sm_621141.html

vanman

3rd Jul 2002, 12:56

This thread is drowning in repetitions!

Sponix see Alpha Leader's comments on previous page.

Standard_Departure

3rd Jul 2002, 13:05

Even as a controller, I have to say that it saddens me to see that there are still those who are referring to the scenario as though the T154 pilot could have done much about it.

To be honest, I see both sets of pilot's as though they were rabbits stuck in the headlights of an oncoming truck.

The ATC system appears to have put the aircraft in a very dire situation, and now claims that it is their fault because they ducked instead of diving.

Quite honestly, unless there is some (as yet un-forthcoming) reason why the ATC's attention was not on his Radar Display, providing simple Standard Separation (timeously), I can see no excuse for ATC.

It may well be that over-reliance on MTCD has given the ATC staff a false sense of security.

It is also known that (in ATC) most incidents occur when the traffic levels are low and the ATC is not paying 100% attention to the task at hand.

Findo

3rd Jul 2002, 13:07

With 150% hindsight and making no judgements whatsoever for all professionals involved going about their duty ….

So far the situation looks like –

Geneva ATC had their ATC conflict alert off for maintenance.
The sector should have been manned by 2 ATCOs and only one was there. The second ATCO had actually left the building.

Geneva accepted the Russian aircraft at FL360 on a track which directly conflicted with the DHL in the cruise at FL360 and under their control. Normal separation for crossing tracks at the same level would be at least 10 minutes. (If aircraft were on direct routes the advance warning of confliction on Flight Progress strips may have been less obvious or non existent)

Swiss ATC said initially they instructed the Russian to descend 2 minutes before collision. That has now been revised to 50 seconds. ( A time now probably measured to the second from RT tapes)

So far it is not clear what phraseology was used for the avoiding action descent.

It appears no avoiding action was given to the DHL when a hard right turn would probably have been an appropriate option.

The Russian crew did not acknowledge the first call but did acknowledge the second and was descending.

At the same time, if his TCAS was serviceable, it would have been annunciating the RA “climb, climb” as a consequence of the “descend, descend” RA to the DHL.

It is likely then that the Russian was receiving conflicting resolution from ATC and TCAS.

Spoken to in his non native tongue, with less than 50 seconds notice he assimilated two avoiding action instructions, disengaged the autopilot and took the ATC avoiding action and managed a descent of about 500ft.

The simultaneous and similar TCAS and ATC avoiding action kept the aircraft in conflict until collision.

One big lesson pilots may take from this scenario even if not 100% accurate - never, never, never choose not to follow a TCAS RA no matter who tells you or what you think is correct.

Hopefully the industry will not allocate blame but talk about cause.

Oldjet Jockey

3rd Jul 2002, 13:08

Alpha Leader

I understand your point but the sequence for hand over is that first there is a co-ordination between the two ATC units in which the handing over control unit offers the traffic to the receiving unit under certain conditions the main one of which is the flight level of the aircraft concerned. If this is accepted by the receiving controller the hand over takes place. If it is not acceptable due to other traffic already in the receiving controller's airspace he would refuse the offered co-ordinartion and request a different level or a delay perhaps rarely with one or two orbits at the same level to ensure separation and to resolve the confliction. This should all take place BEFORE handover and not afterwards.

Suplementary questions would be: was the aircraft at the c0-0rdinated level? or was there a correct co-ordination with a level bust?

Only time will tell but these are questions that must be asked

Alpha Leader

3rd Jul 2002, 13:11

Findo:

It's ok to say "Hopefully the industry will not allocate blame but talk about cause".

However, given the admission of "breach of duty" by Skyguide, it will be hard to avoid the allocation of responsibility if not blame.

The point is that accidents are rarely caused by "things happening" but by human action.

Greek God

3rd Jul 2002, 13:13

Firstly my condolences to all concerned.

[/QUOTE] Cause 5. Bad luck. Even though both a/c were descending at the time of the collision, an accident was by no means inevitable as has been suggested on the TV news tonight. The chances of a collision were still small, especially since visibility was good. Instead of the catastrophe that happened, we would probably not find out about the incident for some time and it would be 'just another airprox incident'. [/QUOTE]

In aviation there is no such thing as "Bad Luck".
It is perhaps ironic that the swiss cheese simile is used in our Flight Safety forums but sadly it is no less pertinent when the holes line up as they have here. There is obviously a chain of events which could have been broken at any stage from Flight Planning to the final manoeuvres of both aircraft. Many valid points have come out of this forum already without the speculation of what the respective crews may or may not have reacted to. Those professional amongst us will recognise these points without me re-iterating them again. But for my tuppence worth:

TCAS is not infallible but assuming it was working correctly, it has a perceptable lag time in resolving a DESCEND RA to a CLIMB, add the pilots reaction time and the time to change a 90+ ton aircraft's flight path and it all adds up to getting too close for comfort. Yes, believe and react to TCAS but it should be a last line of defence. I find it inconceivable that there was no lateral separation instruction issued by ATC or requested by either aircaft. Personally, if I get TCAS traffic at the same level on an apparent intercept I would query it well before it got to a TA or RA. I would also be aquiring it visually(assuming VMC).
The case mentioned by Pontious? was BA & Pakistan 747s over the Indian ocean, I think, both at their correct opposite FLs except the PAL 747 TCAS had a bent pin resulting in an incorrect alt input to the TCAS telling it that both a/c were co-alt. TCAS did its thing and instructed PAL to climb (up to BAs level) and BA to descend (down to PALs level) Collision avoided as PALs TCAS switched Alt bands as it climbed and thus fed correct inputs plus to the A/C were visual. The kit may be good but it should be used in conjunction with the "Big Picture".
I'm sorry, but I do not believe these two aircraft should have been placed in that situation on a quiet night in the first place. Having been done so consequent actions are open to debate but it does behove all of us to place ourselves in either cockpit and ask "what would I do?"

God Bless all

Alpha Leader

3rd Jul 2002, 13:26

Oldjet Jockey:

Again, I understand more about (Swiss) military ATC than civilian ATC. However, SOP is to have two controllers handle the hand-over, one on screen and the other via telephone.

Your comments thus open up a can of worms, because we now know that one of the two Swiss controllers was AWOL at the time of the collision (and possibly for some time prior to that) :(

Standard_Departure

3rd Jul 2002, 13:33

Does anyone know if there is a minimum equipment requirement from ATC side, for the application of RVSM?

eg: Is there a requirement for STCA or MTCD ?

gjp

3rd Jul 2002, 13:46

Been reading about this terrible incident...I am wondering why RVSM has anything to do with this - we should be questioning why the aircraft ended up on the collision course in the first place - RVSM or normal airspace raises the same concerns - surely if under radar control you should not have this problem. Why was the DHL aircrfat not warned of the situation?

BIK_116.80

3rd Jul 2002, 13:54

Ausatco and Fox3snapshot, nothing at this stage is definitive. That much is obvious.

But there are questions that need asking. Perhaps one of you might enlighten us.

Would you consider that it is reasonable for a controller to first issue instructions to separate two aircraft which are on a collision course 50 seconds (or even 90 seconds) prior to impact?

If the initial instruction was issued that late, then why was it issued that late?

Is it reasonable to expect that an enroute controller should be able to identify traffic conflicts without the benefit of the automatic conflict alerting devices which were apparently offline for maintenance?

After the traffic is handed over, how much time should it take for a controller to identify that a conflict exists?

Skyguide were very quick to start throwing mud, blaming the crew of the TU154 and blaming TCAS. They seem to have been back-pedalling ever since their initial press statement.

Shakespeare, said : “… this possibly would not have happened had BOTH a/c been cruising at STANDARD cruising levels”

If the B757 was on a north-westerly track, and the TU154 was on a south-westerly track, wouldn’t “evens” be standard in RVSM airspace?

Fox3snapshot, are you, in your 3rd July 2002 03:38 post, suggesting that the altimeter setting knob is in some way connected to the transponder’s mode C altitude output and TCAS when below the transition level?

It doesn’t work that way in any aircraft I’ve flown. They all output raw pressure altitude based on 1013/29.92. I have not flown a TU154.

Captchunder, I could not agree more. And bring on one single sky for Europe as well. Refer Flight International editorial on page 3, 11-17 June 2002.

ShotOne

3rd Jul 2002, 14:03

Whatever the lapses in Swiss ATC here, we must admire their news management skills. Anyone reading the newspapers in the UK would be given the impression that blame rested squarely with the Russian pilots.

vanman

3rd Jul 2002, 14:05

Actual aircraft tracks as illustrated on SkyGuide's WWW:-

www.skyguide.ch/img/photos_presse/skyguide-map-detail.jpg (http://www.skyguide.ch/img/photos_presse/skyguide-map-detail.jpg)

Big Tudor

3rd Jul 2002, 14:08

Whilst I can see the benefits of single Euro ATC, I can't see how it would have avoided this conflict. A Euro ATC structure would still employ nationals from all EU countries so the language issues would still exist. (Even if only English controllers were employed, the pilots flying the aircraft would still be non-native English speakers). Secondly, the crash apparently occurred shortly after handover. Any EU wide ATC system would have to be split into regional sectors and handovers would still need to occur between controllers. There is no way one controller could be expected to control airspace from the Arctic Circle to the north coast of Africa! :eek:

Oldjet Jockey

3rd Jul 2002, 14:10

Alpha Leader

Yes prhaps I have opened a can of worms and if this leads to improved co-ordination in the future it may help to save innocent lives.

Your point about the level after trasadingen raises another question that needs to be asked. Is it possible that in the co-ordination/handover the conflict was not spotted and the descent instruction was merely to achieve the standard level after trasadingen and not as a conflict resolution? This could account for an apparent lack of urgency in the descent instruction to the TU. I do not intend this as speculation but rather as a question to be asked during investigation.

What is quite sure is that if the two a/c had been flying at different levels there would not have been a TA or RA, and TCAS would not have become involved. However the tragic incident has drawn out a number of pertinent comments on the use of TCAS that hopefully will be discussed in detail and lead to a better and safer understanding of this potentially useful facility

Alpha Leader

3rd Jul 2002, 14:20

Oldjet Jockey:

Your point re Trasadingen is very valid, although - with only five a/c on his hands at the time - it is hard to imagine that an alert controller would have overlooked the fact that another a/c was at the same FL of 360.

Euroc5175

3rd Jul 2002, 14:22

BBC news are now reporting that due to the 'conflict alert' system (STCA?) being off-line for maintenance, the procedures are for 2 controllers to man the sector (presumably as T & P). An extra set of eyes and ears to make up for the absence of the automated conflict alert, whether that be STCA or Medium Term Conflict Detection.

One of these controllers was reportedly on an "unauthorised break" when the accident happened.

The finger seems to be being pointed at the Russian crew. However, if, and it is only an 'if', both the aircraft were co-ordinated in at FL360, the controller has accepted a planning conflict that should be resolved by tactical means, i.e. vectoring or climb/descent, when on frequency. The fact that reports indicate instructions to change level were only given a minute prior to the accident occurring would suggest that 'avoiding action' was being instigated rather than a routine deconfliction of traffic. Vertical separation should of course be provided before the loss of lateral separation (presumably 5nm in the airspace concerned). Unfortunately, initial indications suggest that ATC error may be the root cause of the accident.

preflight

3rd Jul 2002, 14:33

Maybe it´s time to realise that the old radarbased atc systems needs to be replaced. Ive tried to find a site that explains the new world standard system invented by the swede Håkan Lanz. I think it´s called VDL mode 4. I cant say that this system would have prevented this accident but it sure would have given the pilots a better picture of the situation.

From what I´ve heard this system is up for large scale testing in Spain and Portugal...

Regards// Preflight

Oldjet Jockey

3rd Jul 2002, 14:40

BIK_116.80

I will try to answer some of your questions as an ex enroute controller

Is it reasonable for a controller to first issue instructions.........50 seconds prior to .......?

No if he is doing his job properly and has all the normal flight data available to him.

If the initial instruction was issued that late then why was it issued that late?

Only speculation at this time, the investigation should reveal the answer

Is it reasonable to expect.........without the benefit of the automatic conflict alert.........

I would say yes with the rider that perhaps controllers have been lulled into a false sense of security since its introduction. I certainly never had such a facility and would have been very ashamed to have missed a potential conflict in such light traffic.

After traffic is handed over how much time should it take for a controller to identify a conflict....?

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.

pengjian

3rd Jul 2002, 14:45

This extract from The Guardian's coverage this morning.
I'm an outside observer, and would be interested to hear what those in the industry have to say on privatisation issues and the single sky proposal:

"Would an integrated European air traffic control have prevented the crash?

Air traffic controllers across Europe recently went on strike over the EU "single sky" proposal, under which planes cruising above 28,000ft would be guided and controlled by a unified organisation, avoiding disruptive handovers. The unions claimed it would lead to job losses.
Surprise was expressed yesterday at how little time the Swiss controller had to assess the situation. The Tu-154 arrived in Swiss airspace at 11.30pm, just five minutes before the collision. The fact that both planes were allowed to converge rapidly on one another, both at 36,000ft, was also questioned.
Russian aviation officials said the Swiss controller should have ordered the Boeing to climb away at the same time that the passenger jet was instructed to dive. And why, they wanted to know, was the first warning only given 50 seconds before the point of collision.
Gilles Gantelet, a spokes- man for the European commission, said it was too early to determine whether the "single sky" plan would have prevented the crash.
The accident happened in an area where zones controlled by Vienna, Munich and Zurich converge. One airline pilot said: "It's a busy area but it's well organised. You have confidence in them despite the national split."
Erwin Teufel, the minister president of the German state of Baden-Württemberg, said: "We're looking forward for discussions between Germany and Switzerland to find a way of reducing the overburdened air corridor over Lake Constance."
South-west German airspace has been controlled by Skyguide for more than 30 years.
Skyguide, which was recently privatised, looks after traffic flying over the region and landings and takeoffs at the large regional airports.The agreement is a part of a bilateral contract between the two neighbours which was hammered out two years ago, but has yet to be ratified by either country.
It has come under strain after accusations by Switzerland that Germany has been heavy handed and tried to renege on the agreement in an effort to take over control of large areas of air space and dictate common practices.
There have been several near air traffic accidents in the region, leading critics to say that a crash was inevitable. "
(p.4 The Guardian 3/7/2002)

teeteringhead

3rd Jul 2002, 14:52

Some thoughts/questions which don't seem to have had much exposure on this thread - and I speak as a military aviator with perhaps different frames of reference - but which seem to me to flow from basic aviation commonsense/airmanship.

1. It was a "quiet sector", only 4 or 5 ac to be controlled; so why were 2 planned routes in confliction anyway?

2. Both crews were reportedly working the same frequency, so should not whoever was first on freq have heard the other "arrive" in the sector, and used their SA (situational awareness) to note a possible confliction?

3. We all (pilots and controllers) work less well when underaroused, particularly on a "quiet night". Is there an argument for saying "never mind noise-abatement, let's spread the traffic more evenly through the 24 hrs!"

4. I note the arguments about TAS/IAS relationships and sluggish response in roll (and I know we ain't talking fighters), but we all operate in a 3 dimensional environment; why does the maintenance of separation (by TCAS or ATC) seem to concentrate on vertical OR lateral separation, but not both? Put simply: climb or descend, but turn too!

5. Final point: some talk of the Mk I Eyeball as the final safety net. I was told in training the Mk II was better: it's trained, experienced and regularly checked! Should we lookout more than we do on "quiet nights"?

Before I'm rubbished - please read my caveats again. Like most accidents, there are many links in the chain that caused it (and we don't know yet what those links were, or how many there were). But like all chains, break one link and the chain is gone ..........

DeltaTango

3rd Jul 2002, 15:16

I understood from some of the initial reports that they where at FL260 at the time of the disaster?!?!?

IF I'm correct then the russians might have been completely without RVSM?!?!?

My condelences....may we learn what we need to avoid such disasters in the future.

Roadtrip

3rd Jul 2002, 15:27

It seems obvious that the controller was aware of the conflict, hence the order to change altitude to the Russian jet. In that case, if the controller saw that the conflict could result in violating protected airspace, he/she should have issued "immediate" vectors or climb/dive to the pilots.

Let's wait for the investigation, however, in politics we know how these things go especially when you have four different nations involved.

vanman

3rd Jul 2002, 17:15

does anyone read any of a thread before chipping their pennies worth in? Guys...

tug3

3rd Jul 2002, 17:33

Some dispute as to "Unauthorised break": When STCA offline at night, it is NOT a requirement to operate a two ATCO per sector system. This requirement only applies during daytime (busier) hours.

(Reported on BBC TV 'Ceefax' as having originated from Skyguide)

320DRIVER

3rd Jul 2002, 17:37

If it transpires that the Russian pilot only had 50 seconds notice before the collision it might be wise to stop pointing fingers in this direction.

So let's the see what would have happened if the Tu154 pilot responded normally. Obviously the times I am using are hypotethical but based on my background.

I am also assuming (possibly wrongly) that the controller told the Tu154 to the descend in a normal voice tone.

Action 1. Listen, acknowledge, and process ATC request i.e. about 1 second.

Action 2. Set 35000 in the FCU or whatever they have in the Tu, and then set the v/s to -1000 fpm (normal for a 1000 ft level change) , i.e. another 2 seconds.

Action 3. The Autopilot starts figuring what the pilot wants to do and starts descending, i.e. about 2 seconds.

So that 's 5 seconds gone, leaving 45 seconds to descend at 1000 fpm. i.e. at the intersection point, the aircraft would have missed each other by about 750 feet, still less than the required 1000 ft vertical separation.

JAGS2

3rd Jul 2002, 17:51

Is this not the most significant bit of info , assuming factual
from alphleader post

QUOTE:

Skyguide were also in contact with the crew of the B-757, and had been so since that aircraft had entered Skyguide’s air space over the Swiss-Italian border. The pilot of the B-757 also informed ATC that he was following instructions of his TCAS to descend. This report from the Boeing crew was received immediately prior to the last set of instructions radioed to the TU-154 to descend, after which the collision happened.

The words " RECIEVED IMMEDIATELY PRIOR " jump out at you .
Why if the boeing stated he was decending in line with TCAS instruction , was the TU 154 further instructed to decend after the Boeing message was recieved .
Could the controller in any way have been incappacitated in the time prior to the 50 sec warning and then panick / confusion set in ?

Iron City

3rd Jul 2002, 18:09

And what will CPDLC provide you except another avenue for data to be hosed off at the crew and the aircrafts' avionics? Until there is a real vital use for it it is a waste of money and bandwidth.

Lets wait for the investigation. If it is like many others there will be enough blame to go around.

lukewarmskywa*ker

3rd Jul 2002, 18:13

In reponse to Pengjian:

The notion that European controllers went on strike to protest against the Single Sky proposals is a standard case of media soundbites missing the point.

I understand from the more militant members of our union, and from other ATCO contacts, that the action was actually taken because ATCEUC, the umbrella union representing (I think) 5000 controllers throughout Europe was not directly involved in the negotiation.
Some time ago they 'delegated' (or it was delegated for them) their rights to seats at the table to the ETF (European Transport Federation). Subsequently, the ETF went off on some kind of wrong direction (to ATCEUC 's perspective), and the views of controllers and the ATM professionals were not heard, never mind listened to.

I'm trying to relate this in the most objective, honest way, but now perhaps I should say that my opinion as one of 'Thatcher's children' (apparently) takes over. It seems that the ATCEUC simply threw all of its toys out of the pram, and tried to wail to anyone listening. Of course, in France and other still very much civil-service outfits this is easier to do than at multinational or semi-privatised units.

At Maastricht we made a token gesture of work-to-rule for four hours, and despite much acclaim for the support offered, in real terms it was a pointless and fruitless exercise.

Maastricht in particular (as part of Eurocontrol, at least for the moment) has long supported a single sky. It is infact the organisation's slogan, and its culture. Maastricht UAC has very successfully provided cross-national ATC for 30 years.
The practicalities of a pan-European system are really only in the realms of the technical, not principle.

Would a pan-European system have prevented this accident?
It would appear not. Aircraft often come closer than we would like in an ideal world. We would all need to start talking in soundbites ourselves to avoid the sense of inevitability and tragedy that this real world provokes.

eg. 'acceptable risk' . Is a single midair acceptable amongst five million movements? As risk managers we may have to concede yes.
As human beings and professionals within the aviation industry, we all scream an adamant NO!
For aircraft to collide, serious human errors occurred somewhere.
There is no blueprint for Europe that will exclude human error.

caba

3rd Jul 2002, 18:20

Maybe one of the targets wasn´t shown on the controllers screen? According to the Swiss Accident Investigation Bureau it has happened before (http://www.bfu.admin.ch/common/pdf/1744d.pdf).

And wouldn´t this be a good explanation why the DHL never got an avoiding instruction, and neither of the two planes was instructed to turn???

TomPierce

3rd Jul 2002, 18:55

Right at the beginning of this thread someone suggested that ATC had a lot to answer for. This has been discussed at great length without any real answer. Then matters started to take a turn against the Swiss ATC in ZRH who vehmently defended their position. Who wouldn't I suppose.

Now! The executive director in an interview on TV admitted two things. Their anticollision system WAS turned off "for maintenance" with NO apparent loss of integrity! And, that ONE of the TWO controllers had taken an unauthorised break! "But this should not have impaired the functioning of ATC" - what absolute tosh and arrogance!

They have from the outset tried to set themselves aside from this accident and now they admit this. Does that sound like a system that a pilot would be confident with?

I will refrain from making any further comment.

RatherBeFlying

3rd Jul 2002, 19:27

So how often were/are controllers issuing separation instructions in en route airspace with just 50 seconds to go?

Perhaps this ATC sector developed this habit over time and nobody stopped to consider the size of bet being placed on instant aircrew response made necessary by the lack of margins.

And what consideration was given to allowance for lost comms?

Just to add to the many other good questions that have been raised.

Sheep Guts

3rd Jul 2002, 19:41

Yes this seems to be pointing at the controllers. The fact they have admitted in instructing the Russian Plane to descend only 45-50 secounds before the point of crossed flight paths( impact in this case), is very unerving. 50 seconds at a combined closure speed of say 900kts is about 6-7 miles from impact, to me thats too short. Was there a problem in the handover?
Those with international experience, will understand the problems with language, and handovers to different centres all over the world. Was this a factor this time? The language thing comes up alot I notice.

brockenspectre

3rd Jul 2002, 19:59

Most here in this forum are infinitely more qualified to comment in detail so I have but two questions that have been provoked by all that I have read.

1. What do we know of the experience of the one controller left "in charge" by the absentee second controller?

Something in the back of my mind is saying, "if I were a trainee or new and had been told to mind the fort in absentia and do nothing might I react slowly and only post-haste at the last moment"?

and .. not contradictory but along the same lines

2. Are we actually being told that the timing of 50 seconds for a first/last call to initiate separation where a/c are on a collision course is considered "normal" for Swiss ATC?

If I have misunderstood I apologise, but if not, then are we to presume that "normally" (in daylight hours) for example, congestion of Swiss airspace is such that a max time for an avoiding action call is ALWAYS 50 seconds? If so then clearly someone has been way over optimistic with the ability of a system to cope.

RIP to all souls lost.

All sympathy to the two ATC controllers.

Condolences to families, friends and colleagues.

Engineer

3rd Jul 2002, 20:04

Interesting facts here are that with TCAS a TA occurs at approx 40 seconds from closest point of approach (CPA) depending on altitude related sensitivity and an RA is given 25secs before CPA. Considering the 50 second call not much room for manouvre is there.

One other point that appears to have not been considered in all the other posts is that of the collision height of 35250ft. Here the westbound aircraft had almost completed the necessary descent instruction but unfortunately the north bound aircraft had apparently initiated the TCAS descent requirement. However, everything should become clearer with the transcript of the CVR

As stated by teeteringhead and well covered by CRM courses lose a link and the chain is broken and in this case as others with dire effects.

timzsta

3rd Jul 2002, 20:12

Firstly my deepest condolences to all those concerned. This is a real tragedy and it's up to us all to make sure that nothing like this can happen again.

There is much talk about altitude separation, by various means over this incident. I was an Intercept Controller in the military until recently, not an ATCO' just a "Freddie". But I was thoroughly trained and examined in ATC procedures and separation techniques. I was taught from day one the correct way to separate aircraft is lateraly. A ten degree heading change when aircraft are 40 miles apart will give a lot of separation.

Leaving it to trying to achieve 1000ft separation with 50 secs to go to collision, late at night, with one aircraft from a country whose understanding of English might not be the best, flying an old airliner, is seriously reducing the odds.

Let us let the investigation take its course and have everyone learn from this tragic event.

God bless their souls, may they rest in peace.

Whippersnapper

3rd Jul 2002, 20:26

Seems there are 2 fundamental factors here:

1) ZRH ATC totally screwed up by not giving DHL avioding action, regardless of equipment or number of controllers;

2) 154's apparent failure to respond to radio or TCAS. This leads to the question of whether they had an avionics or electrical problem (even a coffee spilt on the pedestal could cause this). The lack of response could very concievably have been out of their control and the press and Swiss blaming the Russian crew is at the least premature.

ZRH's statement that they leave separation to the last minute is not comforting. As for RVSM, I can't see a problem - they were at the same level, not 1000' apart.

TCAS is a great piece of kit which I understood to be mandatory for ops in JAA airspace. It also takes precedence over any other instructions from ATC or GPWS so it's unlikely that confusion existed over which to follow.

As for the comments about 'too many gizmos' and 'use the Mk1 eyeball' , it's immpossible to tell visually if you're at different levels until you're almost on top of each other when at altitude, and what about when you're in cloud?

Unfortunately the growth of aviation means a greater reliance on fall backs such as TCAS, and like any system it's not 100% reliable. I fly brand new US aircraft and TCAS is intermittent on a couple of them, particularly at lower levels, as the antennas are often poorly sealed and water fouls up the signal.

Standard_Departure

3rd Jul 2002, 21:27

It is fair to say that the Air Traffic System was probably largely responsible for this tragic event. The real question is what specifically was the problem, and how can this be avoided in the future.

Firstly, one must realise that ATC systems around the world all operate and function in a different manner. Whilst we all work on the standard separation minimums as required by the appropriate authorities, we do so in different ways with different tools. We are trained in different schools and in different schools of thought. Many ATC units do not have the benefit of conflict detection, specialised sectors, state of the art equipment and more… with this in mind; it is possible that one ATC would see this mid-air as an absolute ATC (controller) error, whilst another ATC would see this as an absolute ATC (system) error.

There is a tendency in the developed world, to reduce the size of a sector that any one ATC will work, often referred to as sausage factories, where there is a production line (if you will) of controllers working small sectors with aircraft spending just a short time in a sector, and then being moved along.

In other parts of the world (often where there is less traffic), the responsibilities of individual controllers cover a wider range of tasks, a single controller could be working the departures, arrivals, final approach, doing his/her own coordination with adjacent sectors etc, and often, these controllers work without the aid of a safety net (STCA/MTCD).

The importance of this difference is not immediately obvious; after all, both methods get the job done. The difference however is deep. The problems start in the training of controllers.

In the specialised environment, controllers are often not exposed to the “big picture” controlling, they develop their experience(s) in an environment where there is always a safety net, and there is always someone to do the coordination. Technology and redundancy are accepted as standard. Specific methods are used to resolve specific conflicts, and controlling traffic often becomes more of a monitoring function than a decision-making process.

In the other scenario, controllers “grow up” in an environment where they are always required to back themselves, check and re-check their separations, be prepared for Radar, Radio and Transponder failures. ATC’s in this environment will often offset an aircraft’s heading slightly for a climb through, so that in a worst case scenario, a reduction in separation would occur and not a near-miss. They will devise & refine new methods of dealing with situations as they arrise, and always be aware that there is more than one way to do the same thing.

Simply put, there are small tricks of the trade that may or may not get trained in the specialised environment, and even if they are taught theoretically, they are certainly hardly exercised in reality.

What may seem to be a basic task to the “big picture” ATC, might require the prompt of conflict detection equipment in the specialised environment. Additionally it may happen that when faced with a unique and unusual situation, the “specialised” ATC may not be trained or practiced in taking simple & immediate remedial action, or "design" a solution off the cuff.

The bottom line is that if we condition ATC’s to work in a certain manner, using specific tools and safety features, then we dare not expect them to perform at the same level of efficiency when we remove those vital tools. I suppose the equivalent would be to ask a (modern) pilot to navigate accurately using sextant, chart and compass.

So, back to the mid-air,

I am not defending the controller’s actions or lack of action; I only wish to point out that there may be more to the situation than meets the eye (or the ear when the tapes are made public).

As ATC’s, some of us may feel that the resolution to the conflict could have been as simple as an offset heading or an early decent instruction. To other ATC’s, this may not have been so obvious.

If the latter is the case, then the system has failed, and the man is just the last link in a chain of unfortunate and fatal events.