Ultranomad wrote:
According to @what_next, it must be legal in Germany, but I remember being told off by München INFORMATION for flying VFR at FL98 when it was IMC at FL95 and CAS from FL100 up.
You are supposed to fly at “semi circular” levels, so VFR it would be either FL95 or FL85 depending on the direction. With clouds at FL95 you would have to descend to FL75. At your quoted level of 98 you are inside airspace E (withing Munich FIR at least). Flying VFR within airspace E requires a vertical distance from clouds of 1000ft. With clouds at FL95 you were violating that requirement.
Zorg wrote:
Do you fly at the limit if controlled airspace? Do you think it’s prudent to do? Are the vertical limits generally excluded from the airspace? (A reference to an ICAO document or similar would be appreciated.)
Yes, yes, and yes. The ICAO reference is Annex 11, section 2.6:
Note.— Where the ATS airspaces adjoin vertically, i.e. one above the other, flights at a common level would comply with requirements of, and be given services applicable to, the less restrictive class of airspace. In applying these criteria, Class B airspace is therefore considered less restrictive than Class A airspace; Class C airspace less restrictive than Class B airspace, etc.
Definition of a level bust (or airspace violation):
Level Bust is defined as any unauthorised vertical deviation of more than 300 feet from an ATC flight clearance.
Within RVSM airspace this limit is reduced to 200 feet.(EUROCONTROL – HEIDI)
So plenty of margin when flying on the boundary. I’ve been doing for more than 25 years and no one ever “told me off” for it.
But we aren’t talking about a level bust here. We’re talking about an airspace bust, which is an unapproved entry into controlled airspace. 1ft inside is inside. 1ft outside is outside. You’re expected to stay on the correct side.
Nobody expects you to hold an assigned particular level to within 1ft, hence the different definition of a level bust.
When I lived in the Vancouver area (crowded overlapping airspace blocks), I used to cruise at the limit between two controlled airspace blocks, or between controlled and uncontrolled airspace.
However, a couple of times it became clear that there was some confusion with ATC, i.e. They thought you were with the other block or were uncontrolled. When it was sorted out you might get a talking to or the wrong hand off, or no hand off. This might not surprise UK airspace users, but is unusual in North America where everything is well linked together.
After a couple of these incidents, I decided it was best to act according to your purpose. If you want the upper block, choose a level within that block. If you want the lower block (or uncontrolled) then choose something definitely below, say a couple hundred feet.
That being said, when requesting climb clearances or for a short water crossing, I wouldn’t hesitate to go right to the line, I just wouldn’t cruise there for an extended period.
Isn’t there room for some common sense here?
Skimming along at the boundary brings the risk of confrontation. Yesterday, I was merrily operating at the boundary (lateral) of two of the most consented pieces of sky in the world, the Israeli/Arab border. Do I fly to the line or do I fly at the boundary? The reality is that I impose a self defined buffer; flying at the limits is like playing chicken, regardless of the law.
Dave_Phillips wrote:
Isn’t there room for some common sense here?
I agree that being PIC should be about making decisions with a common sense, but sadly regulations seem to sometimes push us in another direction.
With respect to my original question, there are lots of cases where a VFR pilot might deviate from common sense due to fear of getting busted (although it might be perfectly fine for ATC to fly at the lower limit):
Two examples:
What’s worse, in my opinion, is the latent FUD we have to fly around with if such things are not crystal-clear. “The lower level of this TMA is at 3000 feet, so let’s fly at 2900 feet. Wait … what happens if my altimeter is off by 50 feet, and I drift off by another 100 feet. Somebody told me that some guy had to pay a fine of EUR 50k for a small level bust. And somebody else told me that in the UK they now introduced unlimited fines! I’d rather just fly around the whole TMA with a wide berth thing to be sure!”
Another point: As expanding commercial air traffic renders uncontrolled airspace a commodity in Europe, we VFR pilots should probably too aim to utilise the available airspace more efficiently. To add several hundred feet of safety margin due to an unclear situation doesn’t sound very efficient and may in some cases be a safety factor.
Just fyi, Italian TMAs (or TMA sectors) with limits defined as AGL are no more.
AeroPlus wrote:
The limit belongs to the airspace below
Actually the lower-class airspace. The boundary between class G and class D is class G regardless of which is above/below.
I then filed a complaint and indeed was told that formally I was correct, but it was common practise in the UK to fly a little lower.
That’s totally the spirit of SERA. Not. 
The UK has/had some totally self evidently bizzare stuff e.g. here
you can fly along the red arrow
You could not make this up! The middle case is complete nonsense.
