Tcas

[fmgc]

Today when working Brest Control we heard a UK LoCo call "TCAS descent". The Brest controller said "Negative, Negative, maintain FLXXX, the aircraft will be levelling off a 1000' above you." Quite rightly the LoCo continued his TCAS descent and told the controller so.

In light of the tragedy over Switzerland a few years ago I can not believe that a controller would actually try and tell a pilot to ignore his TCAS.

I am amazed and admire the pilot's tolerance of the controller. I hope that an MoR was not only filed about the RA but also about the standard of ATC.

[5milesbaby]

Good on the flight crew for still obeying the TCAS instruction, I hope that this will get a lesson drilled in to all the French controllers about dealing with TCAS.

[ToPocHi]

Yes, even I have to agree to that. For a controller to tell the flight crew to ignore the RA would be something of great folly as this was the very cause of the crash itself in Switzerland a few years back. Even cadets know that.

[126,7]

Many ATCOs have already forgotten about that fateful accident and many of the youngsters haven't even heard of it or if they have, don't know any of the details. Sad that a person takes such little interest in their job.......
FWIW, I've never heard an ATCO telling an aircrew to ignore the RA.

[fmgc]

Just to add more details, I believe that the LoCo was in level flight and the conflicting a/c was descending to a 1000' above his level.

[Daysleeper]

the aircraft will be levelling off a 1000' above you

How the heck could the controller know that, he might have been cleared to that level but to tell someone to ignore an RA is totally unacceptable. I hope the MOR is not ignored like so many seem to be.

[Avman]

Yes, even I have to agree to that. For a controller to tell the flight crew to ignore the RA would be something of great folly as this was the very cause of the crash itself in Switzerland a few years back. Even cadets know that.

The above quoted post from ToPocHi could be misinterpreted depending on how you read it. Those of us who have read the report know in what context he means this. But to those who haven't, it may sound as if the controller specifically instructed the aircraft to ignore an RA. This was NOT the case.

Back to this latest case: yes, absolutely unbelievable. It comes down to poor training and lack of professional discipline.

[ATC Watcher]

Very correct reply Avman, thank you.

Topochi : if you had read the report you would have found that at the time the RAs started in both aircraft, none of the crew informed ATC.
(the TU154 crew never informed ATC and the 757 crew did so only 23 seconds later, and even that transmission was blocked by another aircraft )
The causes and factors that led to this collision are many in this case and would take too long to mention their interactions here .
Just make sure the cadets you are talking about have the correct facts .

Back to the subject :

The controller reaction is totally wrong and proves once more the lack of TCAS training / awareness/ refresher training , among too many ATC units .
Equally the importance of the recommendation to reduce vertical rate on the last 1000 Ft of a clearance to avoid RAs is too often not stressed enough to crews.

To understand ( but not to excuse) why we end up with these problems are simple, :

TCAS aims at getting 2 or 300 feet between aircraft, to avoid metal to metal contact . while controllers aim at 1000 ft to avoid loss of separation .

This discrepancy in objectives lead to conflicts ,especially if you have other aircraft in the vicinity of the pair involved, and even more if you have another a/c 1000ft below and opposite to the one which is descending.

Now, since the Ueberlingen collision, we finally have clearer guidelines and recommendations. What is making me extremely worried, is that now, only a couple of years later, we are seeing the same reports as before the collision.
I see ( as part of one of my jobs) an alarming rate of TCAS incidents that prove to me that the lessons of that collision and the recommendations issued thereafter , are not followed and that we are back to where we were before.

In one recent incident , a crew , like in Ueberlingen, followed all the way an ATC clearance that was against the RA issued later . What was “ interesting” for us was that this was involving two major “ established” airlines , and 2 very modern ATC units in the middle of Europe.

This proves to me that unless we ( and I mean by we ICAO, Eurocontrol, the FAA, the UK CAA, etc..) re-open the TCAS training issue rapidly , we are going to have another collision in our skies where TCAS will be involved.

[Gary Lager]

There exists the current requirement for specifically training aircrew to follow TCAS RA when in receipt of conflicting ATC instructions, precisely because the frequency of these kind of contradictory directions is significant in ALL busy controlled airspace - before anyone asserts that it is a symptom of general poor ATC standards.

Research has shown that ATCOs mentally sort traffic into two types - those requiring constant monitoring and those who are 'procedurally' separated (as in our case here). When something happens to demand the ATCOs attention to traffic which was considered previously 'separated' then the instinctive reaction to try and either reassert the original instruction (perhaps in denial of a deteriorating situation due to the stress of an impending conflict) or 'rescue' the situation (since despite TCAS now removing the ATCO from the loop the sense of responsibility he/she feels for the traffic is not diminished) it takes considerable mental effort to sit idly by whilst aircraft on your screen are busy doing their own thing in close proximity to one another.

I have seen the same thing many times in tapes of incidents in UK airspace as well: and believe me, the controllers I have trained with here are well aware of their responsibilities when aircraft are in receipt of an RA - it's just often easier said than done, particularly when under unexpected stress.

So don't let's be too quick to criticise the ATCO involved, unless he/she persisted in issuing contradictory instructions - just all take this as a stark lesson in the very real benefit of training for this situation beforehand.

[ToPocHi]

ATC Watcher, Avman: Thank you for pointing the facts out gentlemen. However, the cadets, including myself (also a cadet) are aware of this. My previous post may have been constructed in an ambiguous manner causing some slight misinterpretations and for that, I apologize.
Gary Lager: That makes a whole lot of sense indeed. I suppose that everone has their reasons for carrying out a certain course of action, may it be the flight crew or the ATCO's themselves. All are aiming for a safer and more secure flight. And considering safety has always been the main emphasis in the modern aviation industry, especially during these times, it becomes particularly and increasingly difficult for both the ATCO's and flight crew to carry out their duties without impending stress that would significantly affect their performance. I guess, at times, things can get pretty rough up there.
-Gentlemen, thank you again for pointing out the facts to me. I'm still a cadet, therefore I feel that I may be in no position to comment further. I frequent this site to learn more in so that I may be a more prepared aviator in the near future. Thank you again, and I hope to hear more from you gentlemen by means of forum participation. Cheers!

[Wiley]

I've gotten into the habit of making all enroute climbs in VS mode these days. (I hear cries of horror from the 'danger! open climb' people, and equally from those who go in fear of the VS you're asking for being too much for the aircraft performance.)

I believe I'm covered on both counts by the fact that open descent and open climb are not a problem on the aircraft type I fly (as it is not on all modern types) - the designers fixed that problem quite some time ago - but many (sometimes quite senior) people seem to be unaware of this fact.

On the performance side of things, the ROC I ask of the aircraft is always less than it would take up if I used VNAV or Level Change.

I do it for two reasons
(a) it gets me into the habit of doing it, so that when it is necessary, as in a heavy traffic RVSM environment and I'm busy, I'll do what I usually do, and

(b) (far less importantly, I accept), is a far more gentle manoeuvre and allows you to make the level change without the pax being aware of any change of engine note.

[fmgc]

Gary Lager,

I accept your reasoning but I do not agree with you acceptance of incorrect actions.

it's just often easier said than done, particularly when under unexpected stress

Is that acceptable? I am sure that for controllers and pilots alike that would not be accepted as a reasonable excuse in one was to balls up in the simulator.

I think that once a controller hears an aircraft call "TCAS xxxxx" then he must just acknowledge it and wait for the resolution to complete.

In the same way I think that many pilots do not consider reducing rates of climb or descent when nearing level off altitudes.

The incident mentioned at the top of this thread was caused by the descending aircraft having a too higher rate of descent.

[NiteKos]

I've gotten into the habit of making all enroute climbs in VS mode these days. (I hear cries of horror from the 'danger! open climb' people, and equally from those who go in fear of the VS you're asking for being too much for the aircraft performance.)

Wiley is that your own procedure or is it part of your Company SOP's.

[jetset]

Regardless of what the ATCO said, thats why the boys in the pointy end are paid the big bucks.

It doesn't matter what was said and all may have been well intentioned but this is an example of where the pilot took control of the situation as he/she(?) was trained to do.

Well done guys.

As for ATC if they made a mistake, well it happens sometimes, I mean even I have made one on occasion thankfully my partner in crime saved the day, as usual.

;)

Wiley -

Fair enough but I consider the threat and use the mode most appropriate to the situation, we don't need to dumb down. We need to actively engage with our surrounding environment and behave accordingly. Thats what we are paid to do imho not just thoughtlessly take the easy option. If the skys emtpy use open climb and experience the joy of flight!

Okay, thats enough from me then.

[Bokkenrijder]

Oh well, nothing suprises me anymore about French ATC. Whether it´s NCE, CDG, ORY or enroute!

There is obviously something very wrong with the way the French train their Air Traffic Controllers!

[RAT 5]

I asked this question after the DHL B757 mid-air. No success then, so try again. It might be a Tech forum topic, but the thread is here, now.

Firstly, I believe it is an FAA airspace requirement to have max v/s 1000 in the last 1000', and max 500 in the last 500'. This was even befoe TCAS, and please correct if I am mistaken. If that is correct why did the FAA not also require the a/c manufacturer to program the autpilots to achieve the same? This mode of of operation could have an override button for emergency manoeuvering, but otherwise it would be the norm, or some other settings as thought best; e.g. v/s 1000 in last 1000', as is many airline SOP.
In this day and age of sophisitcated avionics, where the sensitivity of auotpilts is reduced below certain heights on ILS's etc etc. this would be a simple fix. I even heard, after Sioux City, that they tested an autoland using engines only for control. If they can do that, a simple reprogramming of level off technique is simple. I'm still amazed that the autopilot does a good job of reducing 3000 ROC to zero, smoothly, in only 400'.

The requirement for a crew intervention, V/S, into a routine safety manoeuvre, seems not the best method. Further, at high ROC, e.g. 3500, the ALT ACQ trips in well before 1000 to go, and thus the V/S mode is disabled in autopilot ops. The only way the crew can override the A/P and reduce the V/S to avoid an RA, is to disconnect. Hardly ideal.

The solution seems technically so simple. Why no action on the regulators' part?

[MysticFlyer]

Please, we could discuss this matter to death, but really not necessary.

RVSM-RA-Pilot-Action. This is not a chicken/egg thing either....

[ATC Watcher]

RAT 5, be careful not to mix up requirements ( e.g mandatory) with recommendations.

quick facts to help a few answers :

TCAS software was initially designed for the US domestic lower airspace, ( where the vast majority of the collisions were )
Aim was IFR/VFR protection first, IFR/IFR as a by product. It was regognised from the outset that in the upper aispace with ( very ) fast speeds and CPAs the system will behave badly.

To fly IFR ( outside RVSM ) an Auto pilot is not required.

last : TCAS III ( the lateral version ) was officially abandonned. ( although private studies still go on, but with extremely low chances of getting one day implemented )

Current flavour for the after-TCAS II era, is for a (much better ) anti collision system based on ADS-B.

[Wiley]

NiteKos, it’s my own preference, but company SOPs don’t prohibit it.

jetset, I’d take issue with you that I’m ‘dumbing down’ the operation in using VS mode. I’d say that what I’m doing is quite the opposite. The pax aren’t disturbed by a change in engine pitch, I’m probably saving a nanofart of fuel in not increasing RPM quite as much as a VNAV climb, and (far more importantly) I’m using a procedure every time (unless I’m asked to expedite the climb) that will ensure I won’t be responsible for some poor sod having to carry out a TCAS avoidance manoeuvre.

I take it from your lack of understanding of the term “open climb” that you’re not an airline pilot.

[5milesbaby]

fmgc wrote:
I think that once a controller hears an aircraft call "TCAS xxxxx" then he must just acknowledge it and wait for the resolution to complete.
Not at all, you can expect UK controllers at least give you traffic information including whatever their clearance was (ie. descending to maintain 1000' on top) and if the conflict looks close you will also get avoiding action in the horizontal plane. Subsequent updates on traffic information will be passed if thought pertinent until you report "resolution finished, returning to level".

[qwertyuiop]

Wiley,

I have many thousands of hours as an airline pilot but have no idea what "open climb" is. Airbus thingy isn't it? Beware of sweeping statements.

[Bokkenrijder]

open climb (iBus) = level change (Boeing) ;)

[cdb]

I was under the impression that we no longer give horizontal avoiding action in case it reduces rate of climb - traffic only.

[jetset]

Nothing wrong with V/S wiley.

Just expressing my aversion to having procedures that are adopted on every occasion. Its a toolbox, and you use the right tool at the right time.

My apologies if my tone was offensive.

Open climb, similar to LVL CHG on the boeing.

I am probably not an airline pilot but then I am being paid as one so that'll do for me!

[Wiley]

Well gents, while we're all apologising, let me humbly do so as well.

I understood the term 'open climb' (and more particularly, 'open descent'), to mean climbing/descending in vertical speed with no 'safety net' like a built-in altitude capture mode at the end of the climb/descent, (hence the term open climb/descent, as in 'no end to it', or 'unprotected').

I think I'm showing my age in assuming that younger aviators would have the same understanding of what I thought to be a common term, which dates back to 707 days (and probably earlier).

The first generation passenger jets had pretty basic flight directors and autopilots with lots more traps for young players than today's do, and one of the real traps was the dreaded ‘open descent’, which was quite literally a killer, and which was part and parcel of selecting vertical speed as the descent mode. In VS mode, ALT CAPTURE mode was disabled, even with a lower altitude dialled into the FMA window. And so pilots quickly learned to avoid this trap by avoiding descending in VS mode.

The auto pilot/flight director designers learned from the shortcomings of their first designs and put in the fix of having altitude capture mode engage when VS mode was selected, (so long, of course, as a lower altitude was selected in the FMA window).

However, many 'old hands' had had it heavily drummed into them that VS mode was a serious no-no in descent because it gave you an 'open (ie, unprotected) descent', and even after the newer aircraft with the more sophisticated flight director/auto pilots came into general use, many old hand trainers and checkers still insisted that VS mode should never be used because that was what they'd been taught and had become used to, (and many's the FO or trainee captain who's had to swallow his objections and utter those well known and oft repeated three letters of the aviation alphabet - Oscar India Charlie - (“Oh, I C [see]”) when the ‘old hand’ trainer wouldn’t listen to his explanation that that particular trap had been made safe). It's still posible to get yourself into an open descent with the new kit if you forget to set a lower altitude in the FMA window, so the old salts still have a point.


jetset, apologies for the snide remark, but to belabour my point: I’m of the school that thinks that when you get really busy, you tend to fall back into the habit patterns you use every day. So I’m inclined to do ‘unnecessary’ things and follow ‘unnecessary’ procedures that 99.9% of the time aren’t in fact really necessary. But on the day when all the holes in the proverbial pieces of cheese line up, maybe that ‘unnecessary’ procedure I always do (and do the same way every time), even when I ‘know’ it isn’t necessary, might just provide one last piece of (hopefully solid) cheese in the line and, (to mercilessly mix my metaphors), break the error chain.

[Warped Factor]

This ATSIN ACAS INTERFACE WITH AIR TRAFFIC CONTROL (http://www.caa.co.uk/docs/33/ATS015.pdf) describes to UK ATC their responsibilities following a TCAS RA/TA.

May be of interest in this discussion.

WF.

[5milesbaby]

Good link warped factor, and although it says that ATC no longer become responsible for standard separation I would not like to be the one that doesn't give any vectors and then have a nasty due to some problem in executing the RA's. If the blips are going to merge and a resolution reported by any pilot says that standard 1000' or 2000' isn't going to be maintained then I WILL issue vectors. I'd like to see any ATCO that can morally argue against that, after all we are providing a SAFE, orderly and then expeditious service.

[ayrprox]

if i'm climbing or descending someone 1000ft below/above i'll almost always tell both parties,especially if the rate of change is particularly good. at least that way both crews are aware and so far,touch wood, it has meant no annoying paperwork.
theres tempting fate for you:E .....

[chevvron]

Personally I just say 'roger' and pass details of other traffic which might give him an RA when he descends.

[NIMFLT]

Good link warped factor, and although it says that ATC no longer become responsible for standard separation I would not like to be the one that doesn't give any vectors and then have a nasty due to some problem in executing the RA's. If the blips are going to merge and a resolution reported by any pilot says that standard 1000' or 2000' isn't going to be maintained then I WILL issue vectors. I'd like to see any ATCO that can morally argue against that, after all we are providing a SAFE, orderly and then expeditious service.

ATCO's are not required to separate an aircraft undertaking an RA manouevre from other aircraft. Traffic information and a requirement to report resuming cleared level are all that it required. We are providing a safe service to the extent we are allowed. If aircraft are going to make RA manouevres when there is no danger, then the system is taking the situation out of our hands until that aircraft resumes its clearance.

[cdb]

I agree.

Although I've never had a RA occur on frequency, I would just acknowledge and pass traffic.

As said earlier, I'm sure I read somewhere that there was a concern that the large bank angles from asking pilots to take horizontal action could reduce the climb rate below that required by TCAS.

[5milesbaby]

Having had quite alot of RA's on frequency I agree that normally you just let the event happen and give traffic information, with updates if needed. However on one occasion I did face a situation which compromised obtained separation and avoiding action was subsequently given which was considered in the following investigation to have been pertinent to aid the safety of the a/c, not only against the RA traffic, but subsequent tracks that would have posed a threat if the courses of all continued.

[Few Cloudy]

5milesbaby,

In your previous post you mention reporting "resolution over, returning to level".

If this is supposed to be SOP after an RA then it is not good. Far better to check all round with ATC what is now the best action isn't it?

By following the RA we have followed the operation of last resort and hopefully averted an accident. By climbing or descending BACK to level without clearance or guidance we would be taking a big chance and possibly creating a second conflicting situation.

FC.

[BOPralph]

A quote from the BFU accident report -

"Utilizing its own mechanism and international resources available ICAO should ensure that all ACAS/TCAS users are consistent in their response to the equipment advice. ICAO auditing processes must pursue compliance with its ACAS SARPs and training objectives at all levels within the aviation industry."

Mike J's info above shows many of the good words have been written (and there are many more), and others have brought facts that reflect the intended use of TCAS within the aviation system. But the evidence shows that the level of understanding is lacking.

TCAS is good... but only if everyone knows what they are supposed to do. We don't. And someone should be driving this point harder.

The BFU considered it a 'systemic cause' that "the integration of ACAS/TCAS II into the [aviation system] was insufficient and did not correspond in all points with the system philosophy". If the Ueberlingen tragedy is repeated 'systemic cause' could be replaced with 'guilty parties'.

[cdb]

Fair enough then, if you have plenty of practical experience I shall try to learn from it!

Thinking about it now, do you mean that horizontal AA was used to prevent further losses of separation with other A/C?

[5milesbaby]

Few Cloudy: from CAP 493 (http://www.caa.co.uk/application.aspx?categoryid=33&pagetype=65&applicationid=11&mode=detail&id=222) (Manual of Air Traffic Services Part 1) which is downloadable off the link
Effect on ATC Operations
The effect of advisories on air traffic control operations is as follows:
Traffic Advisory – Pilots are advised not to take avoiding action on the basis of TA
information alone but may ask for traffic information.
Resolution Advisory – Pilots are expected to respond immediately but have been
instructed to restrict manoeuvres to the minimum necessary to resolve the
confliction, advise the air traffic control unit as soon as is practical thereafter and
return to their original flight path as soon as it is safe to do so.
CAP 493 Supplementary Instruction No. 3 of 2005 Para. 3


cdb, what I'm saying is that I would be concerned of letting the blips merge with 2 a/c following RA's that compromises separation and yes, avoiding action was given to overt further losses with other a/c.

[Few Cloudy]

Thanks for that quote 5milesBaby.

That looks a lot better than calling out "resolution over, returning to level", as it contains the important requirement "safe to do so", which the pilot alone cannot discern.

Thus it requires ATC advice / control to return to level.

FC.

[Packsonflight]

Number of times the controllers issue a traffic advisory: "climbing traffic is leveling off 1000 ft below you" Then we simply have to watch the aproaching dot on our Tcas screen and confirm that the traffic is actually levelling off 1000 ft below, it works like a charm.
I dont know weather this is statndad ATC procedures, or simply up to the controller if the do this or not.

[Viper2]

Number of times the controllers issue a traffic advisory: "climbing traffic is leveling off 1000 ft below you" Then we simply have to watch the aproaching dot on our Tcas screen and confirm that the traffic is actually levelling off 1000 ft below, it works like a charm.

I have the same experience and am happy with that to... Moreover it is quite often directly followed by a transmission to the climbing or descending aircraft to confirm the level off.

It makes me aware that an aircraft is approaching "my" level with high vertical speed so I can check that it is really leveling off. The climbing or descending aircraft is made aware as well and can adjust vertical speed to prevent a RA.

Changing software or modifying AP to match TCAS thresholds is a little bit overdone to my opinion. I am lucky to fly a modern aircraft and have never seen the AP significantly overshooting an assigned altitude. Although in some cases it might cause a RA for other aircraft. But when these situations arise VS can be reduced by pilot intervention.

We can ask the authorities to make more rules and regulations to try to cover any possible situation we run into. Or ask the technicians to better program our AP software. But to my opinion it should be up to the guys in front and the guys on the ground behind the screens to manage these situations. That's why we get the big $$$ isn't it? :ok:

[fmgc]

we simply have to watch the aproaching dot on our Tcas screenwe simply have to watch the aproaching dot on our Tcas screen

Many of our A320's TCAS only shows traffic if we have a TA or RA so that little gem will not work for everybody.

[5milesbaby]

Number of times the controllers issue a traffic advisory: "climbing traffic is leveling off 1000 ft below you" Then we simply have to watch the aproaching dot on our Tcas screen and confirm that the traffic is actually levelling off 1000 ft below, it works like a charm.
I dont know weather this is statndad ATC procedures, or simply up to the controller if the do this or not.
Not a mandatory thing but is being used more and more, ironically it has cut down the amount of TCAS RA's! One of those "you will level off as there is traffic" things that tends to make the a/c reduce climb/descent rate in the hope the traffic passes before the level off occurs - or something like that anyhow.

How many of you are aware that calling "traffic in sight" when inside UK controlled airspace (Class A and B at least and I expect Class C and IFR in Class D) actually means nothing to ATC? We even get the occasional "traffic passed down the left, request further climb". We still have to wait for our minimas before offering any further, we cannot permit pilot-visual separation if we are using radar.

[Fubaar]

So from a pilot's point of view (and ATC's as well), to reduce the number of RAs, the poster earlier in the thread who advocated using VS as a matter of course has the right idea.

I know many RAs aren't necessarily opposite direction traffic, but I've often wondered if FMCs were programmed with an automatic offset when above 10,000', (as I remember someone suggesting here on PPrune years ago), whether that would reduce the number of RAs. Navigational accuracy, thanks to GPS (and for the Europhiles, soon to be Galileo) is so high these says that it’s almost too damn accurate in some cases.

[5milesbaby]

You are right Fubaar that RA's aren't always generated by opposite direction traffic, at least 5 of mine were from tracks crossing by roughly 90 degrees, and mostly from 'heavies' descending into the TMA off the ocean cleared on top of European destined traffic out of London, but one I remember well was an MD11 descending FL270 with another MD11 climbing underneath FL260 only going to the East Coast in the States. Between them they had a closure of 7000ft a minute so you can guess the rest...... ;)

[kontrolor]

that's why I monitor vertical speeds of potentially conflicting traffic and when descending/climbing traffic is going to be pretty close to other traffic, I allways give traffic information. it costs nothing and alerts pilots.

[canadairguy]

How many of you are aware that calling "traffic in sight" when inside UK controlled airspace (Class A and B at least and I expect Class C and IFR in Class D) actually means nothing to ATC?
I've also been told (by a controller) that the reply "traffic is on TCAS" is even more useless.

[kontrolor]

not only it is useless, it can be very dangerous (see my topic on verbal abuse)

[ATC Watcher]

Kontrolor, where is your topic on verbal abuse ?

I fully agree with your remark, see the Eurocontrol ACAS safety bulletin nr 6 ( March 2005) that warns about Incorrect use of TCAS traffic display.

[DtyCln]

"Not at all, you can expect UK controllers at least give you traffic information including whatever their clearance was (ie. descending to maintain 1000' on top) and if the conflict looks close you will also get avoiding action in the horizontal plane." 5 miles baby

UK CONTROLLERS WILL NOT ISSUE AVOIDING ACTION IN EITHER THE HORIZONTAL OR VERTICAL PLANE ON BEING INFORMED THAT A PILOT IS RESPONDING TO A TCAS RA.

"On being informed that an aircraft is manoeuvring in accordance with a TCAS
Resolution Advisory (RA), a controller must not issue control instructions to that aircraft." CAP493 ACAS/TCAS Supplementary.

[MancBoy]

DtyCln, does your name suggest those are the sectors you are valid on?

If so, they are my sectors too!

5miles has been valid for at least 5 years, certainly before we moved to swanwick anyway.

[DtyCln]

5milesbaby's identity is well known, therefore I know exactly how long he has been valid.

[5milesbaby]

I stand corrected on what the Part 1 says, I have never however "self proclaimed" to be an expert, but believe I do have over 5 years VALID experience to base a reasonable reply on. If my identity is well known then you would also know that I'm the sort of person who will accept being corrected either on here, or even better have a word with me at work - your reply came across as a harsh personal attack, something that's inappropriate in this thread and on these forums.
Don't forget that the manual also says:
1.1 Air traffic services within the United Kingdom are provided in accordance with the Air
Navigation Order and Rules of the Air Regulations. Generally these are in line with the
standards and recommended practices of the International Civil Aviation
Organisation.
1.2 The Manual of Air Traffic Services contains instructions and guidance to controllers
providing air traffic services. Nothing in this Manual prevents controllers from using
their own discretion and initiative in any particular circumstance.
CAP 493 Air Traffic Services Chapter 1 Paragraph 1
I know its an ambiguous and overused phrase and if it led to an incident then there aren't any legs to stand on without reasonable cause, but given certain incidents, ie. the one portrayed in the recent Sky One program, is there the flexibility to use a phrase like "if it doesn't compromise the TCAS RA then I suggest you make an immediate right turn" to both aircraft involved?
I'd be interested to your replies including any pilot who can shed some light into how a turn of any nature could affect a TCAS RA.

[MancBoy]

5, why am always standing up for you?

Must be the northern connection!

Good luck for saturday in el derby.

Manc

[5milesbaby]

Who needs luck m8 :ouch:

Just £100mil into the fund will do :ok:

[MancBoy]

If i win euromillions on friday, maybe i'll lend city some?

[DtyCln]

TCAS RA Climb instruction from aircraft.
Avoiding action turn from controller.

Aircraft may not be able to acheive required climb rate to satisfy RA due to lack of climb ability due to the turn.

Nearly all civil aircraft in a steep turn will be unable to maintain a level, far less climb.

Again there have been numerous examples hence the reason the lateral avoiding turn was removed by SRG this year based on TCAS encounter feedback.

Early nineties a BA B742 given an avoiding action turn whilst IMC in the hold, LOST 2-3000 ft due to 45' bank angle.

[the_hawk]

Sounds reasonable, plz allow me a non-pilot question: would it be useful to consider an avoiding turn for the a/c with the descend RA?

[DtyCln]

the hawk-

Good point, worth considering by our regulators.

[Max Angle]

Then we simply have to watch the aproaching dot on our Tcas screen and confirm that the traffic is actually levelling off 1000 ft below, it works like a charm.But does not mean that you shouldn't follow an RA if you get one.

[kontrolor]

Kontrolor, where is your topic on verbal abuse ?
I fully agree with your remark, see the Eurocontrol ACAS safety bulletin nr 6 ( March 2005) that warns about Incorrect use of TCAS traffic display.
here it is http://www.pprune.org/forums/showthread.php?t=197083