New Transition Altitude UK & Ireland
 

Saw today this article: here at the CAA website. Consultation will begin, but why no mention of the proposed new level? They obviously have an idea of what will align them to neighbouring states...?

I've heard 18,000ft is on the cards.
How does this work in a TMA? Is there a 'regional QNH' type value for the TMA/CTA?

TMA QNH already exists, it's en-route QNH you need to worry about.
Anyway 18.000 ft sounds a bit high to me. It's OK in the USA where you have those things called mountains, but I would reckon either 9 or 10,000 (as there presently seem to be several 'divisions', such as floor of 8.33khz frequencies and top of LARS, at FL095 at present) or 6,000ft as it already is in some TMA.

The press release specifically states that they want to "significantly raise" the TA, so maybe something above 10k is what they are aiming for?

I had heard that it would be 18000ft and that there would be a push to make this the transition altitude throughout Europe. Which would certainly cut down on confusion.
I wonder if any US controllers would care to offer some opinions. It's 18,000ft there but the vast majority of the US doesn't have mountains anywhere near that. The highest peaks are all in Alaska and the highest in the continental US is Mt Whitney in California at 14500ft.

SoCal,
What did they impact with, the Rockies?
Surely though, your terrain is much higher than ours. We've only got a little pimple called Ben Nevis, (it's 4,400 and something-or-other), and your country is about 80 times as big as the UK.

Eurocontrol (I think) has made a paper discussing the impact of Transition Altitude (TA) and the consequences of various TAs.

I don't remember where it is though (and I can't find it on skybrary) but if I remember correctly the conclusion was something like this:

Low TA, easiest for enroute, least risk of having diffrent QNH for various aircrafts in the TMA (and if you have it they're generally going to airports very close so the diffrence is very small).

Downside is that during certain pressures the approach unit lose several available flight levels and it does complicate the work a fair bit.

High TA, removes the problem with losing altitudes in the TMA. The down side is that you need to start with regional QNH, since you can have enroute traffic going on QNH all the way (short hop propeller aircrafts etc) and you can have streams to airports quite far apart all being at an altitude.

There were also a medium TA option in this paper but if I remember correctly they concluded it was just in between, there are still lost levels in the TMA (just higher up where it might be easier to work with but can cause a ton of problem aswell) and there may still be aircraft needing a regional QNH rather than the airport pressure.


If anyone else has read this paper and remember the location feel free to link it, I will google a bit for it later (or tomorrow, I'm quite tired now :p).

I do by the way blame the terrible grammar and spelling on the fact that I've been travelling all day, it's not intentional :p

I thought they were already trying to roll out a TA of 6000ft across the UK? (I think Southampton/Bournemouth changed fairly recently & Birmingham is changing very shortly). Seems a bit pointless to spend all this time faffing about changing it now if they are going to make it even higher in the not so distant future...:confused:

The question is....do we want to lose the lower level in the stacks [occassionally] or do we want to screw the higher sectors in the most dense and complex airspace over London? Don't forget the massive increase in R/T loading......and that's even before SRG have written a complete chapter on transmission and readback protocol.
People's jobs depend on perceived work output....this is one result......but believe me when I say that the R/T loading alone should kill this off.

I found two documents by eurocontrol discussing and comparing diffrent TAs.

Flight deck perspective:
http://www.eurocontrol.int/airspace/...erspective.pdf
ATC pespective:
http://www.eurocontrol.int/airspace/...erspective.pdf

I and many others have advocated a TA of around 6000ft outside CAS.
It would make life so much easier for everyone and probably reduce the risk of quite a few airproxes which occur precisely because of the risk of confusion between flight levels and altitude.

I would venture to suggest 6000ft for all UK airspace would be most logical, but unfortunately those people in Brussels will probably dictate what we want.

Had a chat with the project manager today and 18k it is.

BD

Raising the TA won't be a bad thing but if it is 18k what QNH would that be based on and would approach units then have to change the aircraft to the airfield QNH later in the approach phase or would QFE make a comeback?. If so what level would that be done?

I Imagine it would be ok as the disparity between say a london TMA QNH and say the birmingham airfield measured QNH would not be as big as you sometimes get between QNE and QNH.

for non uk

QNE = altimeter setting for flight level
QNH= altitude (above sea level)
QFE = Height above aerodrome elevation

Will be interesting to see whether this major change is being tested and run through the enroute iFACTS kit.

How will it cope?

That should thoroughly confuse the uninitiated, particularly the QNE "definition", which, I note, Eurocontrol got wrong as well!

2 s

So what do the 'non uk' people use?

Apart from concise definitions.....

Australia uses Transition Alt 10,000ft, Transition Level FL110 (Min. available Level increases when area QNH is low).

New Zealand uses Transition Alt 13,000ft, Transition Level FL150 (Min. Level also increases).

Both countries use Area or Aerodrome QNH when operating at or below the Transition level, and QNE when above the transition level. I don't have a web link for the Australian Procedures, but the New Zealand procedures are here.

A point to note, New Zealand allows unpressurised operations without oxygen up to 13,000ft (for 30 mins max), whilst Australia only allows operations up to 10,000ft without oxygen.

The only real problem I can foresee in the UK are the extra words that will inevitably be bolted into every transmission "ABC623 Descent now altitude wun tree tousand QNH wun zero wun zero" instead of "ABC623 Descent now flight level wun tree zero. " Another four for both parties... unless of course we can get a bit smarter. Does Mode S pass an aircraft's current altimeter subscale setting?

PM

So about as much as the approach bods will save then?

Not to mention the "to.." and "...feet" !

2 s

And hectoPascals if the CAA get their way

It is proposed that 'hectopascals' will replace 'millibars' in Nov 2011. An AIC will be issued shortly.

...even more words than I thought.

PM

Somehow the Americans manage, unless we believe our own publicity that we are somehow busier and so just won't be able to cope...

You only need to pass the QNH to an aircraft on first descent from FL to ALT, you do not need to add it to every further descent clearance thereafter.

Piltdown Man,

Yes, TC can see it and there is already a warning tool in use with LHR approach that will, within certain parameters, warn ATC if an a/c is descending from flight levels to altitudes on the wrong pressure setting. It works very well and I'm sure will be rolled out further in due course.

Ok, with a TA of 18000ft there are going to be a lot of turboprops plying their routes round Scotland on QNH. But which QNH? This part of the world can see some pretty steep pressure gradients when deep lows trundle by. A Saab 340 operating its schedule from Edinburgh - Sumburgh at 16000ft can easily find a 10 or more millibar(Hpa) difference between the two and that doesn't take into account that they overfly Aberdeen where the pressure will be different from either the origin or destination. Will they have to reset altimeter approaching Aberdeen (bearing in mind that they will be mixing with Aberdeen departures/arrivals who will be on Aberdeen QNH)? Or (as someone mentioned earlier) will Regional Pressures come more into play? If so the constant resetting of altimeters in the cruise would be a real PITA - and kind of defeats the object imho.

DD

Dad, given that in the continent that is North America sees odd bit of severe weather causing a pressure gradient (you know, weather that causes tornados, tropical storms, that sort of thing) yet they manage to cope I'm sure we'll be able to figure out something as well.

I just don't get all the negativity to this long overdue change.

I'm not going to say what I want to see happen, I don't have enough insight in the subject to comment on it.

How ever I'd be intrested to know how a similar problem to the one Data Dad described is handled in the US (because I'm sure it happens), does anyone know?

You raise the levels that an Approach unit would talk to traffic.The example that DD talked about would mean that Aberdeen could control say up to FL195 and overflights at altitude 16 thousand feet would have to talk to Aberdeen.
The airspace below FL195 would become more of a Terminal area,under the control of approach units.It would certainly cause a unit like Aberdeen some issues about pay etc,and not having the staff to take on the role.
Then again leave the system as it is,and you could have different units(Approach and Area)applying vertical separation,with the possibility of different QNHs being used.Now that's not exactly safe.:hmm:

I know its the controller's section of PPRUNE, but as a pilot I would rather have to change QNH in the cruise or early descent when my work load is at its lowest. People always quote the day when a pressure change is 10 mb over 200nm but fail to quantify that it only happens on 35 days of the year, the rest of the time it is much less. The majority of long sectors are flown above 20,000' and it would be a mistake to design the UK air traffic sysyem around the 3 flights a day that route from EDI to LSI. The vast majoity of flights will still be cruising on STD. Of the few flights that dont, they will still take of on one QNH then land on another QNH. The only difference is they will use an intermediate QNH for cruise rather than STD. On a high pressure stable day there might be no altimter changes..... but that would also only be 35 day per year .

What is a problem is having pilots changing from STD to QNH while changing frequency at around 6,000' and the work load is at its greatest.

This excellent proposal will remove a very old but dangerous procedure. Many altitude busts have occurred because of the low TA. The much slated GA pilots will no longer be challenged by lower airspace that could be a FL or altitude with no rhyme or reason as to which it is. This could lead to fewer airspace busts.
Airspace planning will no longer have to stop outbounds at 6,000' for fear of clearing a dim and retarded pilot to climb to a Flight Level with the risk they might forget to change to STD. This will save fuel, reduce noise, increase safety through reduced workload in the cockpit and release airspace/ create more airspace for other airports traffic.
I would prefer to see 24,000' but am equally happy with 18,000'.
As a pilot I can see no down side and found it worked well in the USA in busy airspace.
bb

I agree with bad bear. As a pilot who flies a fair bit IFR OCAS in the UK, I've always thought the 3000' TA was far too low and caused unnecessary problems.
I'd like to see it at an altitude that most light GA didn't have to bother with it, something like 10,000' would be fine, because as has been said already, other things also change there. Alternatively, how about 19,500', can't really see why 18,000' is being suggested, I understand why it's there in the US but not the UK.

I'd rather not lose 1 or 2 levels in my hold when the **** hits the fan, because if it does, we (intermediate ACC/Terminal) get the beating, not the APP sector. And when we do get that ****load of traffic, we need all the room we've got.

Yes, it works in the US. But we are not in the US, so why try to be like them? We don't have the room they have to solve problems!

Correct me if I'm wrong but isn't this TA change going to make it a common TA across Europe, part of the SESAR programme.

Hopefully at some point in the not tooooooo distant future European ATM will be far more joined up and work much more akin to the American system, and not before time. We need to move away from our parochial thinking.

We could "have the room they have to solve problems" if only there was the will to do so.

Ofcourse, but why not implement it after (or simultanously) we have got that bit sorted out?

Don't quite see how a higher TA will create more space between LL, KK, SS, GW, KB, LC, LF and HI.

It will no doubt just be part of better organised airspace and systems.

Ye gads what a negative bunch.

Roffa, I am not against raising it at all BUT 18000ft (as suggested) seems excessive for a country where the highest terrain is around 4500ft.

Whilst I agree the majority of airline flights would still be on 1013, up here in Scotland an awful lot wouldn't be - a large number of Aberdeen arrivals and departures are to less than 18000ft and you then have problems with aircraft on varying QNH's (The quadrantal rule could become interesting!) Personally I think 10000ft should be plenty to remove the GA weekend pilot problem.

Making it higher than 10000ft potentially re-introduces the proven Level-Bust problem of the brain misinterpreting/getting confused by one-zero tousand and one-one tousand, a problem largely solved with flight level one hundred.

If its all about a single-europe, then I would much rather see 'Cleared ILS' happen first :ok:

DD

A valid point, however will making the TA higher than 6000 but equal to or less than 10000ft, affect the efficiency and capacity of the holds in the London TMA?

I'm not averse to the change, but how does it work in practice in the US ?

Let's say you are flying on Airways over a 600NM leg. You obviously have the departure airfield QNH set first, but what then ? Do en-route ATC give you a regional setting ? Are the 'regions' defined (similar to the UK Regional Pressure Setting regions) ?

If not, do you stay on the possibly subsequently innaccurate QNH until you change to the arrival airfield one on initial approach ? How do ATC cope with aircraft on a Heathrow QNH for example who then interracts with one further up the line who is on the Manchester QNH and another on the Belfast QNH and another on the Copenhagen QNH ?

I'd just like to know how the mechanics work in the US and what the workload and RT loading is ... as well as the possible different datums being used and who works out what is separated and what is not.

Sumburgh QNH today is 982 and Heathrow is 1016. That's 1000' difference near enough. Somewhere along the way, it could go horribly wrong unless the procedures are robust enough to ensure that datum differences are addressed. I'd be interested to hear the US solution.

Therein lies the nub of the question - does it work in the US because it has so much airspace, much of it wide open and (compared to Europe, particularly the UK) relatively uncongested?