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User avatar
By editmonkey
#1842328
How in the name of god does this work?

I have a revision question I can't figure out:

A/C is on track 075 degs
QNH = 1010
What is the lowest available flight level?

I came to the answer thus:

Transition layer = 1013-1010 * 30 = 90ft thick
So lowest level = FL035

Eastward track is odd so lowest avaliable FL = FL035

The book gives the answer as FL050

Can anyone clarify this for me please? Is my calculation correct?

Thanks in advance!
User avatar
By GrahamB
FLYER Club Member  FLYER Club Member
#1842372
ENR 1.7 specifies a minimum of 1000’ between the Transition Altitude and the first available Flight Level (the Transition Level) , which in this case would be FL045 (a westbound VFR level) assuming the UK standard TA of 3000’ and a QNH of 1010 hPa.

The first available eastbound levels would therefore be FL050 (IFR) and FL055 (VFR).

The resultant Transition Layer between altitude 3000’ and FL045 would therefore be a nominal 1410’ thick,

Note that SERA.5005 (g) requires all flights to conform with the semicircular rule when above the TA, but the UK exercises its right to not mandate it for VFR flights with ORS4 1423. When flying abroad it’s wise to stick to it; I’ve heard French ATC ask quite insistently an aircraft VFR outside controlled airspace to adjust its level when flying at the wrong one.
johnm, AndyR liked this
By johnm
FLYER Club Member  FLYER Club Member
#1842390
@GrahamB gives a very succinct summary of yet another bit of the dog's breakfast that is UK airspace :roll:
By johnm
FLYER Club Member  FLYER Club Member
#1842400
JAFO wrote:How is it a dog's breakfast not to mandate the use of specific flight levels for VFR flights?



I'm struggling slightly with double negative but mandated flight levels makes sense for when IFR and VFR traffic are mixed so that we have a predictable if not entirely known environment.
User avatar
By David Wood
FLYER Club Member  FLYER Club Member
#1842401
There’s a bigger question which is; what are cruising levels actually for? What is the safety case? What do they achieve?

The semi-circular IFR cruising levels are particularly absurd, given that a significant proportion of IFR traffic will be flying in IMC, with the pilot’s visual look-out compromised. Concentrating such 'blind' traffic into narrow height-bands is plainly idiotic, especially where the choices of available levels is often significantly reduced by Class A above. There are places where there may be only one available level (passing under an airway, for example). God forbid that one day there may be a mid-air in IMC there. If there is, investigators will look, open mouthed, at the rules that obliged such traffic to fly at exactly the same level.
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By A4 Pacific
#1842413
The semi-circular IFR cruising levels are particularly absurd, given that a significant proportion of IFR traffic will be flying in IMC, with the pilot’s visual look-out compromised. Concentrating such 'blind' traffic into narrow height-bands is plainly idiotic, especially where the choices of available levels is often significantly reduced by Class A above. There are places where there may be only one available level (passing under an airway, for example).


A genuine question if I may?

What does a better alternative look like?
#1842422
A4 Pacific wrote:
... There are places where there may be only one available level (passing under an airway, for example).


A genuine question if I may?

What does a better alternative look like?


Mandated EC (in and out) for IMC in class G and flight crew choose their own altitude?

OK, that assumes no VFR in IMC (there shouldn't be any, of course), but doesn't help with IFR in VMC in Class G - nearly there though?
rdfb liked this
User avatar
By David Wood
FLYER Club Member  FLYER Club Member
#1842475
A4 Pacific wrote:
The semi-circular IFR cruising levels are particularly absurd, given that a significant proportion of IFR traffic will be flying in IMC, with the pilot’s visual look-out compromised. Concentrating such 'blind' traffic into narrow height-bands is plainly idiotic, especially where the choices of available levels is often significantly reduced by Class A above. There are places where there may be only one available level (passing under an airway, for example).


A genuine question if I may?

What does a better alternative look like?


What would be wrong with pilots choosing their own levels?