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delay undetermined
21st Aug 2006, 11:37
Hey folks,

I'm happy I understand both a VMC descent and a Visual approach. I understand their use and application and who is responsible for separation etc.

But how does it work close to the ground. I'd be interested to hear controllers opinions on vmc descent to below the MSA? (Who is then responsible for terrain sep?) Followed by a Visual approach? Can you do a VMC descent and a visual approach concurrently?

The MATS1 is specific with each but does not easily translate into the real world where an a/c would want to make a visual approach to an airport but cannot because of IFR traffic below him where the only procedural separation that can be applied is a VMC descent - though its more of a good weather get out clause and not separation standard.

Anyone come up with answers and phraseology?

Cheers.

Tarq57
21st Aug 2006, 12:53
I'm happy I understand both a VMC descent and a Visual approach. I understand their use and application and who is responsible for separation etc

By VMC descent, are you referring to own terrain clearance visually, or maintain own traffic seperation visually? If the former it is the pilot's responsibility to maintain a safe terrain clearance when below MSA. Used in situations where the requirements for a visual appraoch are not yet fulfilled, but expected to be.
If the latter, I don't know. Used to be an option here (NZ) but think it may have been withdrawn. I'd have to check MATS when at work next.

eyeinthesky
21st Aug 2006, 14:30
If you mean IFR VMC descent through other IFR traffic as defined in the MATS 1, (radar not available, one pilot able to see the other, etc.), then you can do that subject to those conditions. It has nothing to do with terrain separation as it must happen above MSA. Unless, of course, you are doing a visual approach, which requires the pilot to have visual reference with the gorund before descending below MSA.

So in the scenario I think you mean: Providing all the criteria for a VMC descent through other IFR traffic are met, you may clear IFR traffic to descend visually though other IFR traffic in order to make a Visual Approach, provided he does not descend below MSA without visual reference to the ground.

Remember that a Visual Approach is still subject to the IFR rules and must be provided with the requisite separation from necessary traffic depending upon the class of airspace. The responsibility for not impacting the ground during the approach rests with the pilot!

2 sheds
21st Aug 2006, 20:19
I don't see any reference to the pilot having to have other traffic in sight or the procedure being limited to use above MSA!

ATCO2
21st Aug 2006, 22:22
Hi,

I have a question similler to one above. I am vectoring an acft for an ILS apch and pilot wants to descend visually to altitude below MVA, how to descend an acft below if it is on radar vector, to what altitude? Condition for visual approach is well known and VMC descent is only allowed if second acft is having first in sight and states that he can maintain own separation and VMC (reff. Doc 4444) but it does not say below MSA or MVA. It is applicable above but not below MVA or MSA in non radar environment (except visual approach is comenced), if someone knows any doc. which describes that, please tell me.

Best regards,

delay undetermined
22nd Aug 2006, 05:49
eyeinthesky you've hit exactly what I'm looking for.

The VMC descent is a separate thing to a visual approach, but if, in order to conduct a visual approach he must do a vmc descent against one other IFR aircraft to avoid delay, how would I phrase it?

And can he do it? do you split it up - ie does he do a vmc descent to a vertically separated level first, followed by a visual approach, or can he do a vmc descent against one bit of IFR traffic (standard separation being provided against the rest) and cleared for a visual approach?

2 sheds, you are right, there is no mention of msa - mats part 1 seems to be aimed at area in the respect of vmc descents. Apparently there used to be a vmc approach, which I guess is what I'm describing above.

ATCO2
22nd Aug 2006, 07:29
Hi,

What VMC descend are you talking about? A Doc 4444 says: acft can descend beloow MSA if it is following a STAR or any instrument procedures or visual approach is being executed. What is VMC descend folowing visual approach? It must be visual approach requested by pilot or initiated by ATCO and agreed by pilot. Which ICAO Doc describes the VMC descend below MSA if Visual Approach is not executed or to descend below MVA if the acft is being vectored?

Thanks,

delay undetermined
22nd Aug 2006, 08:04
Here is both direct from Mats part 1 (uk).

MATS Part 1, Section 1 Chapter 3,

5.5 VMC Climb and Descent
To avoid excessive delays to traffic when radar is not available, controllers may
authorise an aircraft to climb or descend in VMC provided:
a) essential traffic information is given;
b) the pilot of the aircraft climbing or descending agrees to maintain his own
separation from other aircraft;
c) it is during the hours of daylight;
d) the aircraft is flying in visual meteorological conditions;
e) the manoeuvre is restricted to Class D, E, F and G airspace at or below FL 100; and
f) the aircraft is not in CAS-T.
1)


Mats part 1 Section 3, Chapter 1

12 Visual Approach
12.1 To expedite traffic at any time, IFR flights may be authorised to execute visual
approaches if the pilot reports that he can maintain visual reference to the surface and
a) the reported cloud ceiling is not below the initial approach level; or
b) the pilot reports at any time after commencing the approach procedure that the
visibility will permit a visual approach and landing, and a reasonable assurance
exists that this can be accomplished.
12.2 Standard separation shall be effected between such aircraft and other IFR and/or
SVFR aircraft.
12.3 Controllers shall exercise caution in initiating a visual approach when there is reason
to believe that the flight crew concerned is not familiar with the aerodrome and its
surrounding terrain.

Bern Oulli
22nd Aug 2006, 11:08
All not to be confused with "Approach maintaining VMC" (long time defunct in the UK doubtless because of the aformentioned confusion). Quoting from my MATS Pt 1 last updated July 1972, "....IFR flights may be cleared to approach maintaining VMC and their own separation, if reports indicate that this is possible." A recipe for disaster IMHO and a good thing it has gone from the book.

delay undetermined
22nd Aug 2006, 12:14
True ... from what I hear it was being used as a get out of jail free card in some busy airspace!

What do you folks think of this: Traffic info and request for VMC descent given and received, "with a vmc descent against previously mentioned traffic, cleared for a visual approach, report ... etc"

Or is that illegal since standard sep should be provided?!

Any procedural experts out there wanna put me right?

discountinvestigator
24th Aug 2006, 09:21
May I please just make a slightly sideways reference to Aviation Law in the UK, as opposed to MATS Part 1 which is an intepretation document and not actually a legal document?

The ANO 2005, as subsequently amended by Stat Instruments blah blah, Part 9 does not mention any responsibility for air traffic controllers in relation to separation. ICAO Annex 11, last time I looked, had 57 mentions of responsibility for ATC, none of which were related to safety.

The Rules of the Air Regulations 1996 makes specific reference to the pilots having to maintain safe separation from each other's aircraft.

So, under the laws of the land, if you are on approach to Heathrow in Class A airspace, with full ATC service, IFR in IMC (and add a bit of night in for the hell of it), it would appear that the pilots have full responsibility to give way to the aircraft from their left.

Back to reality, all UK ATCOs should check their Unit Safety Case for the interpretation of the phraseology which has been approved by the management for use at their local unit. It is not acceptable in England and Wales to just take the MATS Part 1 standard and apply it. The unit has to show that the standard is relevant to their operations and that a risk assessment has been carried out. :ugh: Interestingly, the laws in Scotland and Northern Ireland are slightly different. However, it would appear that Scottish law is just about the same interpretation as England and Wales now. As for Norn Ieron, well, let's hope nobody has cause to find out! (The CAA may not require you to do a risk assessment for legacy procedures for their purposes of licensing a unit, unfortunately, public expectation is such that you are required to do it, and it is 12 persons from the Clapham Omnibus that will be judging you. "We changed the procedure after the accident..." is not good enough any more.)

And before you fry me, (i) I defend controllers in court, (ii) I spend a lot of time lecturing on the finer points of corporate manslaughter exposure in aviation.

Happy landings and PM if you need to know more.

Discount

2 sheds
24th Aug 2006, 10:12
Discount

Several points, please, re your interesting post.

The MATS Part 1 is not a legal document but is, surely, the medium through which the Authority specifies how the task is to be performed.

The ANO might not refer specifically to ATC responsibility, but any significant lapse on the part of ATC could still result in a charge e.g. of endangering an aircraft, could it not?

I am surprised that you say that "it would appear that pilots have full responsibility" when Rule 17 states quite clearly that "Notwithstanding that the flight is being made with air traffic control clearance it shall remain the duty of the commander of an aircraft to take all possible measures to ensure that his aircraft does not collide with any other aircraft" - which obviously must include compliance with rules of the air if necessary.

QUOTE=discountinvestigator]
Back to reality, all UK ATCOs should check their Unit Safety Case for the interpretation of the phraseology which has been approved by the management for use at their local unit. It is not acceptable in England and Wales to just take the MATS Part 1 standard and apply it. The unit has to show that the standard is relevant to their operations and that a risk assessment has been carried out. [/QUOTE]

I am sure that this will be news to many people - what is your justification for saying this? How does this assertion square with the Authority's requirement that standard phraseology is used for specified situations? And surely, any such unit-specific phraseolgy that might be appoved should be in the unit MATS Part 2? "All UK ATCOs" should not have to delve into the Unit Safety Case document to determine ATC instructions.

2 s

discountinvestigator
24th Aug 2006, 12:13
Hi, ooh the debate has started!

The MATS 1 point is really, that just because a procedure exists in MATS 1 does not mean that it is appropriate for your unit to use it. By this I mean that the unit may chose to use a subset of MATS 1 procedures, just because it is there does not mean that you have to have it. There are some areas where you may chose to develop additional procedures, subject to CAA approval, which do not conform to MATS 1 and operate as a "trial" etc...

On the subject of endangering an aircraft, it would be most unlikely for an ATCO in England and Wales (now why can I see half of Prestwick resigning at this point and heading for Southampton?) to be prosecuted successfully without deliberate rule violation errors coming in. If for example, you deliberately vectored an aircraft into a hillside in IMC because it was flown by your wife's new boyfriend that she left you for, well maybe we get into the realms of possibility.

The point of law, now again, please do not fry me here, you may need this...., is that an air traffic controller is responsible for the following
(i) turning up to work approximately on time
(ii) to have had sufficient rest
(iii) to be in a fit physical state
(iv) to be in a fit mental state
(v) to want to do a good day's work (should be shift really)
(vi) to apply the procedures given by management to the tasks
(vii) to use the training and experience in applying those procedures.

Your job is not to make up new procedures on the spot. Your job is not to take shortcuts with the current procedures. Should you wish to change a procedure, put it to management and say why. They may (i)either ignore you, in which case carry on with old procedure (ii) tell you why the procedure change is inappropriate (iii) change the procedure having done the safety analysis.

Now, I do not wish to knock controllers in any way, but you would be defended against a manslaughter charge on the basis that you are an "operator" in the system, not that full responsibility rests on your shoulders alone. That is the point of SMS, you know where you sit. You do not carry insurance, your employer does. You will find that expert evidence and a good barrister (yes, I know one...) have managed to argue successfully for other system operators in multiple manslaughter charge cases, such as most train drivers.

I used the word "appear" as I am confident in what it says, but we have not had it tested in case law. I hope we do not either!

By interpretation of the phraseology, what I meant was that if you have a procedure and its associated phraseology, it will be defined somewhere what is meant by it. It should be what is meant in MATS 1, but remember, some units do different things. Remember the holding point and holding position argument? Many units are not very good at explaining procedures to controllers, just bang out another Temporary Operating Instruction and off we go....

The unit safety case should have all of the boundaries for the application of procedures listed within it. The MATS 2 may not. This is where MATS 2 formats tend to be hopeless. Many are about 40 years out of date in terms of good procedure format, but ATC are a conservative lot....

The MATS 2 should explain why the procedure is there, the hazards that it is designed to manage, the scope and boundaries of its application, the required equipment and say MET conditions, who can use it and when, what training is required and all of the operational limitations, contingency procedures etc, not just the procedure itself.

In fact, you should find that airport related procedures come from the Aerodrome Manual first, then into MATS 2, but that is a whole other subject (oh, I might excuse LBIA as they do airport and ATC in house, and the other units like that).

IF and only IF your MATS 2 contains all of the information you need to apply a procedure, then that is where you have to look. If it does not, then at least tell management that you are missing some of the important operational application limits in it. I can assure you that the instructions to the controller at the heart of the mid-air over Germany had a set of operating instructions that were not worth the paper they were written on.

What I would also say is that we are trying to get it right in the UK. You should see the rest of the world, with a few exceptions.

2 sheds
24th Aug 2006, 13:42
So, under the laws of the land, if you are on approach to Heathrow in Class A airspace, with full ATC service, IFR in IMC (and add a bit of night in for the hell of it), it would appear that the pilots have full responsibility to give way to the aircraft from their left (sic!!).



Discount

I would have thought that pilot responsibility in an ATC situation was demonstrated frequently, e.g. in a circuit scenario or in the ground movement scenario if ATC has not informed an aircraft that another is holding but otherwise appears to be conflicting.

I would be slightly more impressed with the other assertions if there were some quoted authority or precedent. What exactly is the authority (or relevance) of the list of controllers' responsibilities ("a point of law")? The reference to the "holding point" v "holding position" episode seems to be quite irrelevant to the particular argument and, from what I recall, is actually a good example of ATCOs rising as one and getting SRG to get a formal grip on events.

Which leads on to the remarks about various MATS Pt 2 - if they are so lacking, perhaps you should be directing some of this criticism and advice to SRG - who approve those documents.

Meanwhile, back at this thread, what is your answer to the original post?

Pierre Argh
28th Aug 2006, 15:48
discountinvestigator... I read with interest your comment about legal liability. I realise I'm taking this thread off subject, but hope readers will bear with me?

Bowing to your apprarent professional knowledge, perhaps you'd explain "Vicarious Liability"... a phrase much banded around. Some use it in the sense that the employer has it, if one of their staff messes up; but in another sense I've heard it used that the employer can absolve themselves of responsibility if they can prove their staff had been properly breifed and trained, so that they shouldn't have messed up?

If, as you suggest, a Controller is "an operator" in the system and therefore not fully responsible; why could the RAF court-marshalled the controller involved in the Ben McDui F15 CFIT incident (much about which has been posted elsewhere on this Forum).

Finally, (excuse me I may be getting out of my depth here, but IIRC) isn't there a scenario whereby if the employer is called as a witness for the prosecution (i.e. to answer questions on the acused devaition from standard proceddure) they cannot act also for the defence... so they are unable to stand-by their employee (I believe this scenario might have happened in another fatal accident)?

DFC
29th Aug 2006, 21:55
To answer the initial question, when operating visually, one is not required to remain at or above the MSA. The legal basis for this is in the IFR rules (ANO). When operating below 3000ft AMSL clear of cloud and in sight of the surface, there is no requirement to be 1000ft above all obstacles within 5nm of the aircraft.

Unless being vectored, the pilot is solely responsible for terrain spearation. That separation can be acheived by flying at a pre-calculated height which will provide the required clearance or visually avoiding obstacles.

Remember that visually avoiding obstacles is an approved procedure in the departure phase as well as the arrival phase.

ATC will not vector the aircraft below the MSA or the minimums specified on the radar vector chart. Thus the visual approach will be commenced at a height which is terrain safe. At the moment that ATC clears the flight own navigation (for a visual approach perhaps) then the pilot becomes solely responsible for terrain separation.

-----------

discountinvestigator,

Interesting view. However, Annex 11 gets straight to the pooint that objective number 1 of ATC is to prevent collisions between aircraft. Obvously it is recognised that ATC can not acheive that objective for every aircraft airbourne every day. Thus, the Airspace class system is used to clearly indicate to pilots the level of service ATC provides and thus the ATC objectives / responsibilities. The parts of (for example) UK airspace where ATC are going to provide separation between flights is legally notified in the AIP in accordance with the ANO.

Thus ATC can not be held responsible for a collision between say two VFR flights in classes C to G and they can not be held responsible for two IFR flights colliding in class G (or class F if one is not participating).

You are correct to say that the aircraft commander is responsible for avoiding collisions with all aircraft on the ground and in the air. However, the task of acheiving that responsibility can legally be delagated. For example the view to starboard from the P1 seat of a B747 is limited by the aircraft structure. The P2 however has a much better view and should spot aircraft to starboard which we may be required to give way to. Similarly when operating in controlled airspace and in IMC, the task of ensuring that we do not collide with other aircraft is delagated to ATC.

In VMC, then the pilot is fully responsible for avoiding collisions despite what ATC may be doing.

The whole system is organised to make this work. That is why ICAO VMC criteria require all VFR flights in controlled airspace where ATC do not provide separation from IFR flights to be 1000ft below cloud. Thus ensuring that the IFR flight just above the base of cloud will be 1000ft above a VFR flight below. Unfortunately, the UK has decided to permit such VFR flights to operate right up to the cloud base making things harder for ATC and more dangerous for both IFR pilots and the VFRs who don'tknow better.

Thus while a collision between two aircraft regardless of rules and so called local service provided in class G would be pilot error, two IFR flights welding together in class A airspace and in IMC would be very much an ATC error. An ATC error the cause of which could be laid firmly at the feet of the ATCO only following an investigation.

Regards,

DFC

Spitoon
29th Aug 2006, 22:28
discount, whilst I would dearly like to take each of your points and disect them individually, I do not have the time right now and I suspect that even if I did it would not change your views one iota. However, what you are doing is blurring the purpose of aviation legislation - which is there broadly to provide a framework consistent with the responsibilities of the UK to comply with ICAO and to do what other bits and pieces that the MPs, that we elect, may wish to add - with more general legislation that relates to health and wellbeing of individuals and employees (where the individuals happen to be employed).

Whilst I'm no a lawyer, my understanding is that the latter invokes concepts of 'duty of care' and the like and uses expressions such as 'all reasonable measures to ensure that...' and that courts are there to judge whether those reasonable measures were taken. This legislation sets the framework for societal values generally, not aviation in any specific way. When a court is deciding whether reasonable measures were taken by, say, an ANSP, it would consider whether the relevant aviation legislation was complied with.

On a couple of other points, you are right that Annex 11 doesn't go into great detail about how an ATC service achieves its objectives but PANS-ATM does. What is more, PANS-ATM mentions separation quite a few times - and it this document that MATS Part 1 is largely based upon.

You also make a number of assertions about the way that deviations from MATS Pt 1 (and thus ICAO) are managed - for all of your claimed expertise, you appear to misunderstand the UK regulatory framework because mot of these assertions are incorrect. You may not believe that the UK regulatory system is right but if you are going to cite it, please make you comments on the system that is in effect rather than guesswork or how you think it should be.

I will now await the inevitable tirade in response and, maybe, when I have more time, we can engage in some usefuk and informed debate.

All rather off-topic, but you started it.

Pierre Argh
30th Aug 2006, 08:53
DFC when you say the task of ensuring that we do not collide with other aircraft is delagated to ATC and In VMC, then the pilot is fully responsible for avoiding collisions despite what ATC may be doing I think it is better to say that ATC will assist the pilot in collision avoidance... IIRC the pilot is always, ultimately responsible for the prevention of collisions irrespective of airspace and IFC (hence ACAS procedures?)

(This debate on responsibility might be a good topic to prune off onto a thread of it's own?)

2 sheds
30th Aug 2006, 20:47
"Rule 17 (1) General
(a) Notwithstanding that the flight is being made with air traffic control clearance it shall remain the duty of the commander of an aircraft to take all possible measures to ensure that his aircraft does not collide with any other aircraft."

ATCO2
30th Aug 2006, 21:17
Just to say few words about separation. What I have read somewhere above, I am not quite sure is correct. IFR flights are to be separated from A to E class airspace and separation is responsibility of ATC not pilots , except the second aircraft is in visual contact with one in front of and requesting VMC descent maintaining own separation. In that case separation is given to someone who request it. I cannot understand that somebody here can say that IFR flights in VMC conditions are separated by themselves. Where did you read it and where do you apply this kind of separation?

One more thing what I asked before. Aircraft on a radar vector is requesting to descent visually (in that case is going below MVA) but not requesting visual approach, would you allow him/her to do it or not?

Answer will be highly appreciated.

I do not expect answers based on national regulations of some countries. I expect answer based on ICAO rules and regulations.

Many thanks.

DFC
30th Aug 2006, 22:28
Pierre,

I agree with your wording. If I remember corectly, that was the wording in Annex 11 some years ago.

---------------

ATCO 2,

I am trying to think of a reason for an IFR flight operating normally in controlled airspace would be requesting to descend visually (below that applicable minimum safe altitude) but not make a visual approach. Are they going to wave to Mamma and then climb back up or regain a safe level later when the level is lower?

Regards,

DFC

Giles Wembley-Hogg
31st Aug 2006, 08:21
DFC

Barcelona on westerlies. Radar vectors to the ILS often leave you a shade high if ATC bring you in tight. High(ish) ground on base leg means ATC cannot offer a lower level unless you are visual with the surface. By reporting visual with the terrain beneath (and obviously maintaining safe separation from it), ATC can allow you an extra couple of feet descent, thereby allowing a nice high speed, CDA ILS to be flown.

G W-H

Pierre Argh
31st Aug 2006, 19:17
gwh... no names, no pack-drill, but at a certain unit in the UK we used to routinely ask pilots if they were visual with the surface, and then would say "maintain your own terrain clearance, descend to.... ft"? We could probably get away with it because we were working in Class G (it might have even been before those classifications were introduced?)... but it helped get pilots in when weather was marginal IMC