Level Restrictions Question

[Neptune262]

Well I will let PPRuNe Radar come back with his response for your specific question but my take on the subject in general is as follows...

Because the pilots are questioning if relative restrictions still apply to new clearances, if there is a chance of either mis-understanding or assumption on the part of the pilot, then the controller should re-state that the restriction still applies, if that restriction is still what the controller wants, or say that the restriction is lifted if the controller does not require it anymore.

Also if the pilot is in doubt and the controller has not made it clear, then the pilot should ask for clarification.

As we all know, we all have to go above and beyond the required procedures on occasion, so to save the necks of all concerned, make it crystal clear what you want.

[AirNoServicesAustralia]

When an amendment is made to a clearance, the new clearance must be given in full to the pilot by the air traffic controller, and this new clearance automatically cancels any previous clearance.

This phrase is what I was getting at. You choose to put that only into the context of if the level is changed any other level restrictions are cancelled unless restated in the new clearance. The phrase above clearly states that when issued with a new clearance the clearance cancels any previous clearance. That said as I outlined in my examples, does that mean that any restrictions that were issued as part of that original clearance are cancelled along with the clearance.

Example. ABC cleared DESDI for the DESDI 4V arrival descend FL150, speed on the descent not above 270 kts Indicated.

Next call is ABC you are now recleared direct to UKRUM for the ILS RWY 12L, descend A100 QNH 1012.

As far as your quote from the UK CAA Ops Notice to pilots, says subsequent clearance cancels previous clearance. Does that also cancel the speed restriction that was part of the original clearance?

BTW I still think in the case given where,

An aircraft is given a clearance, 'descend FL150, cross XYZ FL180 or below' and then receives another clearance of 'descend FL130'. Does the 'cross XYZ FL180 or below' restriction still apply?

that the restriction is automatically cancelled, is crazy and in my opinion open to errors by pilots and controllers alike.

Also I don't appreciate the condascending tone about the amount of traffic in someones airspace. We all have our unique challenges and the airspace around Dubai has more than its fair share. Try working with the Iranians for a few days and see how you get on.

For Neptune, maybe the alternative (since the existence of this need for clarification means that despite what PPRune Radar says this isn't black and white for everybody) is to make the whole situation crystal clear for everyone by making it that any requirement but me specifically cancelled by a controller otherwise it continues to be required. Seems pretty crystal clear to me.

[PPRuNe Radar]

Also I don't appreciate the condascending tone about the amount of traffic in someones airspace. We all have our unique challenges and the airspace around Dubai has more than its fair share. Try working with the Iranians for a few days and see how you get on.

That's not what I was getting at, and I suspect you know it deep down. I was trying to illustrate that the practice of having to restate a restriction seems not to be an unacheivable burden in parts of the world where traffic densities are high, and so where you might expect the procedure to be unworkable. So it can probably work in other areas too (which have their own local problems as you allude - but unconnected with this debate). The US invented aviation (in the form of mass transport we know today), so if they invented something that works and ain't broke, why fix it ??

I still think folks are losing sight of the fact that a clearance has up to 4 elements which are not intrinsically linked (unless a link is stated as part of a specific condition) - namely vertical profile, horizontal profile, speed profile, and time constraints. If you change one element, you only change that element in the reclearance, the rest remains the same (unless you have linked it to another element and then it requires restating or amending).

Otherwise, if we take the logic of a reclearance being everything previous is null and void, we would have aircraft routeing direct to their terminal fix and climbing/descending as they wished simply because we told them there was no ATC speed restriction on departure !!!

[AirNoServicesAustralia]

Similarly, if the original clearance included a restriction, e.g. ‘cross XYZ FL180 or below' then the issue of a revised clearance automatically cancels the earlier restriction, unless it is reiterated with the revised clearance.

You talk about the 4 elements of a clearance, and if you change the specific element that relates to the restriction then that restriciton is cancelled. That isn't what your own advice to pilots says. It says that if you reclear an aircraft restrictions relating to the previous clearance are cancelled.

Above and beyond that, please tell me the logic of a rule where you have a restriction due to crossing aircraft at FL210, so you give a requirement to be FL220 by a time/place. The aircraft is climbed to FL270, then FL290, and then FL310 as the upper levels become available, all while the aircraft is still in the FL's below the crossing problem. Why does it make sense that while you are not changing a level that has anything to do with the segment of the flight trajectory that the restriction relates to, that restriction keeps getting cancelled and having to be restated? It keeps getting said that this works and so the rest of the world can and should do it this way. Do you think you could open your mind to a different way of operating and even just consider that there are others out there that may have a better way of doing things. I am certainly not saying that Australia or Australian controllers have the answer to everything and do everything as efficiently as they could, but just maybe on this one, they have something.

[BlueSkye]

Here is a SID: " After departure RWY36, maintain runway heading to 5DME ABV, turn left heading 300 to intercept R340 ABV outbound. Climb to FL080 and cross 15DME ABV FL040 or above. At 25DME ABV set course as per flightplan. "

So on first contact you identify the aircraft and clear the aircraft to climb FL120. Does this automatically negate the requirement to "...cross 15DME ABV FL040 or above."?

[airman13]

Certainly YES unless the controller says ''proceed as cleared''.

[BlueSkye]

Certainly YES

Irrespective of the reason for the restriction on the the SID?

[BlueSkye]

unless the controller says ''proceed as cleared''.

As cleared by who, the SID or the ATC?

[CDN_ATC]

Bottom line:

A responsible controller would re-itterate if it's still required.

A responsible pilot would either meet the restriction anyway, or inquire to the new controller.


Simple, safe, and easy, no need for discussion really.

[AirNoServicesAustralia]

Thats bollocks CDN. There is a need for a discussion because certain parts of the world do it one way and other parts do it another way. Just cos ICAO have their tea parties in Montreal doesn't mean they are always right.
All I get in response to my questions as to why a requirement to get an aircraft above a crossing aircraft at FL150 should be cancelled by a revised final cleared level of FL350 to FL370 is that "That is just the way it is".
My answer is no, that is not the way it is everywhere, and IMHO it shouldn't be that way anywhere cos it is plain stupid and makes no sense.

Bottom line, a responsible Air Navigation Service provider will ensure that an ATC requirement is cancelled specifically rather than cancelled by default due to a revised clearance.

[PPRuNe Radar]

I think you can make a case for either way of doing things and there's certainly no lack of respect for the Oz way. It's just that I think the other way is more cast iron because I know the restriction is cancelled and will either not be adhered to, as expected, or alternatively the pilot might adhere to the restriction anyway which will be no big deal. The other benefit is there are more airspace users throughout the world used to doing it this way. The problem with assuming that the restriction will still be adhered to with the other method is that some pilots won't, because they have not been trained to do so. This might end up with you getting egg on your face.

The bottom line is that we should standardise things so that pilots know what to do, wherever they are from. If the standard is 180 degrees out from what I personally would like then I either live with it, or live with it in the meantime and try to get it changed through the appropriate channels. But any change is going to take a long time and a lot of debate and lobbying if you want to change the world who might all prefer the current way of doing things anyway.

[airman13]

BlueSkye, I meant ''as cleared'' by the previous ATC.

[BlueSkye]

PPRuNe, in your notice in post #20 under amendments, it mentions that the vertical profile of the SID is cancelled if you climb the traffic above the "SID FL." In your books this provides ample opportunity for a mess. A SID is designed so as to keep you clear of inter alia, other SIDs, STARs, other airspaces and the big daddy, terrain. It also provides guidance in radio failure procedures and cuts R/T time.

I am perfectly happy with the fact that when you issue a heading before the SID is completed, the entire SID is cancelled. In this case ATC would then be responsible for terrain clearance, which was provided for in the SID. What does not sit well with me is the part where you give a climb instruction and then the vertical profile is also cancelled. Lets go further, if the vertical profile is cancelled why not just cancel the whole thing and upon receiving climb (as mentioned earlier), route direct to your first waypoint.

To say "Comply with SID and climb to FL120" would be a contradiction, because the SID clears you to FL080. Semantics, maybe, but this is suppose to be black and white.

What if you are in a procedural environment? Then you must wait for the aircraft to level of at the end of the SID before giving further climb? Or report passing the built in vertical profile level before issuing further climb? If you do climb the aircraft higher on first contact and the pilot disregards the vertical profile and fly into high terrain, then what?

The question I guess is, which parts do you adhere to and which parts do you disregard? Do you as a controller assume that he will comply with part of the SID, half of it or all of it? Where is the line and do you always have the time to consider these possibilities?

Sorry, but the UK way leaves way to many unanswered questions.

[BlueSkye]

One more thing,

a clearance has up to 4 elements which are not intrinsically linked (unless a link is stated as part of a specific condition) - namely vertical profile, horizontal profile, speed profile, and time constraints. If you change one element, you only change that element in the reclearance, the rest remains the same (unless you have linked it to another element and then it requires restating or amending).

Correct me if I'm wrong, but this is exactly my point. If your clearance contains a clearance limit with a vertical profile requirement at point XYZ and you change only the clearance limit, then the requirement does not change. The vertical profile is linked to XYZ not the clearance limit.

Obviously if the clearance limit changes to either above or below the profile requirement, the restriction becomes null and void. If a route reclearance is given that omits XYZ from the route, then the vertical profile restriction is cancelled because XYZ was the link to the vertical requirement.

My head is going to explode, good night.

[Blockla]

Amendment to ICAO

11.4.2.6.2.5 Level restrictions issued by ATC in air-ground communications shall be repeated in conjuction with subsequent level clearances in order to remain in effect.

Does this now mean that SIDs, STARs or other 'plated' procedures must be complied with as the levels/restrictions etc. aren't issued over "air-ground comms"?

Thoughts?

Has the UK updated your procedures/doc yet?

Also see this link