FL420?

[dynamite dean]

Can some enlightened ATC boffin answer my question. Just curious yesterday evening flying over the Netherlands to Ireland at FL400 I asked the controller for the next level up - he said you can have FL410 or 420. Well without sounding like an amateur I have never heard of this - being cleared to that level. 410 and 430 etc always get the limelight i guess there isnt anything wrong with 420 but I am puzzled i didnt think it was a level?

[beamwidth]

FL420 is certainly a level, but it is not vertically separated from FL410 nor from FL430.
RVSM airspace tops at FL410
There was a case some time back when 2 aircraft were sitting on top of one another at FL410 and FL420.
It was only when the flights were passed to the next FIR, and a query was received, that it was realised that they had been like that for quite a period of time.
If there is no traffic at FL410 or FL430, then there are no vertical sep issues.
Not to be recommended though

[VectorLine]

I am puzzled i didnt think it was a level?

Why? Did you think there might be a gap in the space/time continuum?

If cleared, you can fly at any level you wish. FL415 would probably be acceptable if there was no other traffic at 41 or 43.

Same sort of confusion existed when we first started giving out FL300 post RVSM. Pilots soon got the hang of it when they realised their a/c didn't dissapear up it's own contrails when they levelled off at that level

VL

[bekolblockage]

Now, is F415 separated from F400?

[ayrprox]

yes it is !

[PPRuNe Radar]

Depends if the aircraft are RVA or RVN

[Spitoon]

Now, is F415 separated from F400?

It's not levels that are separated...or not, it's aircraft. A VectorLine has pointed out it's only a separation problem if there is another aircraft around.

Many years of working approach has highlighted similar concerns and misunderstandings around the Transition Altitude/Level. My job is to keep the aeroplanes separated by 1000ft vertically - I may temporarily assign an altitude to an aircraft above TL (or, heaven forbid, temporarily assign a level in the Transition Layer for 'cruising') in my known traffic environment, but so long as I achieve 1000ft vertically I've won the game. The rules do not stop me from doing such things. Whether it is good practice or a good idea is something else.

[ONE BIRD]

Now, is F415 separated from F400?

of course it is. where did you get your license from?

[VSD]

ayrprox & bird

Really?

Why does RVSM not extend to F430 although majority of traffic cruise between F290 and F410?

Shall we consider the height keeping accuracy and issue of tolerance at such high level, inter alia, F415.

[thorisgod]

separation ensured

of course 415 is separated from 400. If 410 is separated from 400 then anything above is too. Duh! How else would you climb an aircraft to 430 from 410 when it is already separated from 400.

look up the word

Separated:
adjective
-existing or happening independently or in a different physical space:

[bekolblockage]

Thanks for your answers to the bleeding obvious.

The reason for asking was that we constantly deal with separation between traffic at F400 and traffic from Mainland China at 12,500 metres (F411).
We had a devil of a time convincing the bosses that they were separated when RVSM was introduced in China. Interested in seeing other peoples rationale.

[radarman]

spitoon,

What do your LCE's have to say about your creative interpretation of altimeter setting procedures?

[Spitoon]

radarman, I should perhaps have put my post in the past tense because I'm not working operationally at present. But my LCEs never had any problem with the practice.

Nor did my 'creativity' generate any adverse comment from a trapper who witnessed my using an altitude above Transition Level for a minute or so. It was a while ago so maybe the CAA view has changed - and it does tend to depend on the who you get from the Belgrano! But as I recall we discussed it, I explained that I was using an altitude for an unplanned temporary stop above TL for a short time - less than a minute I would guess - to assure separation without requiring lots of altimeter resetting etc. Trapper appeared content that there was a reason and that I knew what I was doing. Mind you, I think it was that time I got a rollocking for something else!

[dynamite dean]

Thanks for all your answers - So as a pilot not hearing FL420 that often why doesn't it get some more use? Similarly can I ask for F440 If I so wish? I can see a fair few colleagues saying 'thats not a level etc..' thats why i posted it here!

I take the point that so long as you have 1000ft at least I can really go to any level.

cheers

[Dee Mac]

Not quite dynamite, you'd need 2000' sep at FL440. The reason those higher levels don't get much use is because aircraft don't ask for them, those up at say, FL450 for example get direct routes everywhere - due to lack of other a/c at that level. Sod's law does dictate though that you will have a conflict somewhere, it happened to me at FL450. FL660 I'm glad to say was "clean" of other traffic on the only instance I've controlled an a/c at that level.

[LapSap]

DD

With many aircraft flying around at ....380,390,400,410 the next naturally separated level is 430 then 450. The opportunity to use 420 and 440 just doesn't arise very often. Doesn't mean they can't be.
Just like pre RVSM, 300 was a legit level but almost never used as it would block the normal hemispherical levels at 290 and 310.

[45 before POL]

I remember your flight coming over the North Sea, mainly as said before ...not a normal allocated level, but as nothing at FL410 and FL430, why not? However not recommended practice at busier times, phone calls were made to onward sectors to ensure that it was not overlooked about the separation issue.

[dynamite dean]

Cheers experts,
I meant to say 2000ft seperation out of RVSM;

45 before pol - Many thanks for that keep up the good work boys and girls

[FUN.LEVER.FORWARD]

I had a US mil pilot request F420 in oceanic airspace once and thought the best action was to clear him into a block F410-F430 as those two levels are unavailable to other a/c. There is also a good chance the a/c is operating close to the limits of its flight envelope so a little room for manoeuver also helps. Easy to do over sparsely used ocean but not really a goer in high density airspace, where I wouldn't accommodate such a request.

[vapourer]

The UK MATS Pt 1 says "Cruising levels at or above FL410 up to FL660 shall be allocated according to the semi-circular rule, therefore, Flight Levels available are:
Eastbound FL410 450 490
Westbound FL430 470 510

"shall" means that the instruction is mandatory, therefore I would say that FL420 is simply not available for allocation.