Total disconnect between Eurocontrol and ATC

[IO540]

Many times I have filed a route at say FL150, which I noted would have a huge overhead of say 30-40% if filed at non-oxygen levels of say FL090.

On the day, if it's a nice day, I ask for a "stop climb" at say FL090, to conserve oxygen. The MPG is more or less constant FL080-180, and in the absence of a tailwind to exploit there is no point in climbing higher.

Sure enough, on the day, I sit there for 3-4 hours at FL090, all the way...

How is it that ATC are perfectly happy to handle traffic tactically at levels which the Eurocontrol computer would never dream of accepting?

Is there some kind of job creation scheme in Brussels, concerned with creating thousands of airway restrictions every day - which the relevant ATCO, with the radar picture in front of him/her, tosses straight in the bin?

For this reason, I never file below FL140, and ask for a "stop climb" at FL090/100 if there is no IMC evident enroute. Obvious exceptions (mountains) aside, this works at least 90% of the time.

[fuzzy6988]

Could this be a post for the "ATC Issues" area?

[bookworm]

Is there some kind of job creation scheme in Brussels, concerned with creating thousands of airway restrictions every day - which the relevant ATCO, with the radar picture in front of him/her, tosses straight in the bin?

"Brussels" does not create restrictions. The restrictions come from national ATC, and are assembled into the RAD by Eurocontrol.

What's the route in question? Without concrete examples it's difficult to answer your main question.

[IO540]

Try routing (with FPP) any substantial route across Europe at FL090.

[bookworm]

Try routing (with FPP) any substantial route across Europe at FL090.

I do both route and file across Europe at FL090 most of the time. I appreciate that your trips are often a lot longer than mine, but I don't have that much difficulty.

The only such restriction I regularly have to plan around is the FL120 minimum on L984 over FFM. My experience, though not recent, is that traffic at FL090 really is in the way, though Langen is always helpful in finding a mutually acceptable plan, whether by coordination or rerouting.

Conversely, FL90 over Amsterdam is plannable, but effictively not flyable as Amsterdam want you at FL100+ over the TMA. Again, if that's an operational problem, there are contingencies involving a handoff to Approach.

If you give specific examples of where FL090 is not plannable but always flyable, we can give the appropriate feedback to CFMU to get the restriction amended.

[IO540]

I had a super example which I flew a few weeks ago but, today, it works OK at both FL150 and FL090...

That is itself not suprising.

What I don't have is the actual airway restrictions which prevailed on the day, and which prevented the FL090 routing being accepted by Brussels, but which ATC did not care about on the day. To have those to hand I would have to do a screenshot from FPP.

[M609]

Some of the problem can be that many ATS routes are not defined below base of CAS, or just not defined below say FL100 or there abouts.

I know Sweden (Which has blanket FL95 base of the enroute CAS) block ATS routes below FL100 via IFPS. (Not DCT)

Other tings that might throw a wrench in the works are terminal airspaces that block IFR transits in TMAs, or that only allow filing via special designated routes. (And those routes might be allmost impossible to find in the AIP, or indeed know of their existence at all)

From a controller standpoint, if I get a flight that has filed say FL140, and during climb states that FL90 will be final cruise, I can only assume there is a operational reason for that, and will coordinate the flight accordingly.

[bookworm]

From a controller standpoint, if I get a flight that has filed say FL140, and during climb states that FL90 will be final cruise, I can only assume there is a operational reason for that, and will coordinate the flight accordingly.

As do most other controllers. The problem comes when the different level, accepted without a problem by the controller upstream, causes a capacity issue for the sectors downstream. Rarely a problem at FL140/90 I'd guess, but quite an issue where a level-cap is undermined by a higher clearance upstream.

The solution comes from balancing the need for flexibility in operations with the need for advanced planning of ATFM by a suitably joined up ATC system. But we're a way away from that as yet.

[IO540]

Time and time again, on IFR flights FL100-FL190, I see exactly zero traffic anywhere near my level. I'd happily fly from here to say Austria, and give you £20 for every plane we spot within say 2000ft of our level

Admittedly, a 737 may not be visible say 30nm away, but 30nm is way more than the horizontal separation applied in CAS under IFR.

That whole "GA level" airspace is more or less an empty void.

Presumably, this is why a different cruise level works on the day, despite CFMU-enforced restrictions. ATC can be pretty relaxed about the traffic, most of the time.

Stuff like overflying Frankfurt is different (FL120/130 min, IIRC, or you get a big dogleg) and also overflying the Alps

I am sure M609 illustrates at least reason why lower levels can result in poor routings.

So......... who is it that draws up these restrictions?

[niknak]

IO540
It's already been pointed out to you, but let me put it in simple terms.

Your world: You file your flight plan, you think the world will revolve around you, you get airborne, you seem to think that just because you can't see anyone else or hear any other aircraft on the frequency you are on no one else is out there. Why shouldn't you do what you like?

Real World: You file your flight plan, the Eurocontrol Computer studies your route, takes into account every restriction across the entire route you have filed and adjacent routes and sectors, it takes into account all other filed flight plans for aircraft which will be climbing and descending from/to aircraft in the areas you will be overflying, it takes into account the forecast weather much further away which may cause aircraft flying in the same airspace as you to be delayed or re routed.
Once you are airborne the tactical ATCOs have a real time picture of what is going on and are able to offer the flexibility available.

Had you posted on the ATC forum in the first placed you would have saved yourself a lot of embarassment.

[IO540]

it takes into account the forecast weather

Gosh I never knew it was that clever

Next time a filed route is rejected, I will know why

Thank you for your pompous arrogant reply, anyway.

[niknak]

The truth hurts.....

[IO540]

Having been to your "international" airport and had my toothpaste confiscated, I assume they have just promoted you to Head of Security

Anyway, I am always willing to learn new stuff. So, tell me, how does CFMU work the "takes into account the forecast weather"?

Start with an easy example, of a flight plan being filed (or just validated) say 4 days in advance.

[mm_flynn]

Originally Posted by niknak

...you seem to think that just because you can't see anyone else or hear any other aircraft on the frequency you are on no one else is out there.

This is a fairly common comment from ATCOs. From the pilot's view - you are flying along in crystal clear air with plenty of time to look for traffic and can't see any, have TCAS and don't see anyone anywhere within 10 miles and 4000 feet, look at the ADS-B radar tracks and don't see anything other than your own aircraft, visit Swanwick on another day and the airspace is empty - yet we are assured there was lots of traffic right nearby that we didn't see. What should we be looking at to see the traffic?

I have been assured there is a ton of jet traffic on the DVR KOK link at FL100 - F130 yet I have only once ever seen anyone else (an opposite direction twin) and every after the fact radar trace seems to show the jets at FL190 by DVR.

[bookworm]

Time and time again, on IFR flights FL100-FL190, I see exactly zero traffic anywhere near my level. I'd happily fly from here to say Austria, and give you £20 for every plane we spot within say 2000ft of our level.

Sure. But the controller who is working your flight is also working the flights that are 10,000 ft above you and 50 miles away. So the constraint on capacity is not so much about the capacity of the airspace physically to accommodate your aircraft, but the capacity of the controllers to give you the attention you need.

[Fuji Abound]

I always set TAS to unlimited so I have got a pretty good idea what traffic is around - above, below, up above, underneath.

You can also get a pretty good idea by looking at any of the on line services that show traffic throughout Europe that is on an IFR plan in CAS.

I would also be interested to know how and when the weather becomes a factor.

[mm_flynn]

Originally Posted by bookworm

Sure. But the controller who is working your flight is also working the flights that are 10,000 ft above you and 50 miles away. So the constraint on capacity is not so much about the capacity of the airspace physically to accommodate your aircraft, but the capacity of the controllers to give you the attention you need.

There are two different questions. One is about capacity (space and controller) and the second is about the intrinsic structure of the airspace (as defined by the airways and the published restrictions). I think IO's question was on the second point.

Niknack's summary broadly corresponds to my understanding of what the flow management unit does, however, in my experience it is rare for flow management to be a factor for a light GA flight (other than arriving/departing/transiting a busy TMA). Equally, it would seem an unusual set of conditions that meant the workload for handling someone at FL100 vs FL140 would be different (other than that the FL100 aircraft might actually be talking to a terminal controller rather than enroute - (see busy transit point above)

On the second one, there are a number of airways where the base is set to go over a modestly busy airport controlled airspace (Nantes is an example from memory). I suspect this is done to simplify the above flow management logic, in that CFMU doesn't need to think about transiting aircraft in this airspace.

However, there are other examples where the controllers view of what should be happening and the published restrictions are different (there is an odd one once again into Nantes where the obvious route from the Southeast wont validate, so you file something that works and then fly the obvious route!). From comments from a Northwest based controller I believe if you file to leave his airfield via the published standard route with a Reroute Accepted remark, you will have your flight plan modified off the standard route and then the controllers will clear you back onto the Standard Route.

I suspect for those cases where a TMA causes the enroute airspace to bump up over FL100, it is just that most of the time the airfield is not busy and it is fairly straight forward for the controller to clear you through (just like a ad hoc transit), however, some days it won't be and you will wind up at your filed level.


ps - I believe in 'bad weather' the sectors can declare a reduced flow rate and this increases the odds of a flow restriction being applied.

[IO540]

But the controller who is working your flight is also working the flights that are 10,000 ft above you and 50 miles away.

Indeed, but that factor should work against me getting the "CFMU-impossible" FL090 routing on the day.

I can see CFMU imposing a slot due to controller capacity limits somewhere along the filed route, but then one has to ask the obvious question: where has this traffic disappeared to on the day?? I don't think the controller is busting his employment/union rules just for me... especially if the frequency is pretty quiet. At least 90% of IFR traffic is regular CAT and they fly mostly to repetitive flight plans. They shouldn't just vanish.

Somebody out there is creating rules which for some reason are meaningless on the day, and it certainly isn't due to traffic volume which has gone missing at the last minute.

I suspect one reason might be what mm_flynn suggests: the lower airways have artificial capacity limits which are wasted because CAT is doing CDA descents which don't go anywhere near low enough.

I can't file/fly above FL200 but I wonder what it is like at the bottom end of the upper airways e.g. FL210/220. There is virtually no CAT there (except the London-Brussels run, etc) but you get the benefit of the relatively straight upper airway routings.

[bookworm]

Indeed, but that factor should work against me getting the "CFMU-impossible" FL090 routing on the day.

No the point is that all levels have to be considered for both flow rates and RAD routing restrictions. If a sector takes in all levels up to FL195, and most traffic wants to fly from the usual entry point to the usual exit points at FL180, then routing the traffic in a particular way via a RAD restriction can help to reduce the controller workload and increase sector capacity. But unless the RAD restrictions are made insanely complex, those restrictions are going to apply at the planning stage to FL100 too. When you roll up on the day at FL100, the controller sees nothing else close to the level and gives you a DCT to wherever you want to go.

Usually, that doesn't cause an operational difficulty for an aircraft, though admittedly sometimes it could be better to have a more fine-grained restriction. But if you don't give examples of these "CFMU-impossible routings", it's very difficult to see your post as anything other than a rant.

[M609]

To get the "fine grain" restrictions you would in effect need a much more precise CFMU system (or similar), and some of that functionality can be seen as part of the 4D trajectory ops the SES boffins dream about.