Sure that’s not gone with SERA?
Dave_Phillips wrote:
Isn’t there room for some common sense here?
Skimming along at the boundary brings the risk of confrontation
There are many cases where you need to ‘skim the boundary’ (particularly altitude boundaries). For example, the Manchester low level route. You need to fly pretty much at the ceiling of the Manchester LLR if you want to be able to “land clear” should your only engine stop running since there’s built up areas right in the middle of it. Similarly any area where the base of controlled airspace is close to the ground, for example, I used to live in Houston and the I-10 corridor runs between the KIAH and KHOU class B surface areas with the B starting at 2000 feet above. It was best to get flight following from ATC (who would instruct “at or below 2000”) and fly exactly 2000 feet. It would give you the most options in the case of an engine failure since the area is very built up, and nearly everyone else is flying at 1500 feet, so you’re also less likely to meet someone coming the other way.
you can fly along the red arrow
501ft AGL to FL064 (Class G) VFR non-radio
FL065 (base of Class A) VFR with a special “airway base crossing” ATC clearance
above FL065 is not allowed because there is no VFR in Class A
You could not make this up! The middle case is complete nonsense.
Indeed it is. The only case where “at the base” was an issue in the UK is for IFR, where quadrantal levels were mandatory. Thus there was a question as to whether that level was available for flight at the base. For VFR, you are clearly permitted fly at FL64.99, and not at FL65.01, so “at the base” is irrelevant.
I think I eventually managed to persuade the UK CAA that an IFR flight should be permitted to cruise at the base as if it were the lower class (inevitably class G), but I have no idea if that was ever published, or how many angels danced on the head of that pin.
Dave_Phillips wrote:
Isn’t there room for some common sense here?
No, common sense is substituted with rules and regulations 
In this case I’m not sure exactly what common sense should be. Clearly the ones flying in the more restricted airspace should stay further away from the limit than those flying in the less restrictive airspace, but other than that? It is potentially much more dangerous for someone in a more restricted airspace “busting” into less restrictive airspace than the other way around, but it is also a much more unlikely event. In my opinion ICAO is the common sense, and looking at that level bust definition, the 300 feet of vertical space in the more restricted airspace is per def off limit for someone flying in the more restrictive airspace.
@Dave_Phillips wrote:
Isn’t there room for some common sense here?
My common sense tells me why have a rule to which class a common level belongs to if you’re not supposed to be flying there? It seems obvious that ATC can assign it to you. And you’re not expected to keep a level to +-1 feet (there is a good chance you’ll have bigger variation between your altimeters than that). Of course, if it’s your choice, there is a question of how polite it is.
Isn’t there room for some common sense here?
Indeed. On airspace designers not to over-classify airspace, on pilots to pick up that radio and request a clearance, and on controllers to grant those clearances where practically possible – all done before an aircraft reaches the border.
DFS in Germany has recently issued an information note that touches this topic (in German):
In summary, they’re urging VFR pilots to not fully exploit the vertical (and horizontal, for that matter) boundaries of their airspace for various reasons, most notably wake turbulence caused by heavy aircraft potentially just 500 ft above you. They argue that in approach sectors (reverse wedding cakes) the IFR traffic will often by assigned the lowest available flight level, which may be just 500 ft higher than the airspace boundary. The also say (which is no news) they have to report any intrusion to the authorities.
I don’t see much room, literally, for the argument “when I fly at the airspace boundary, I can expect a 200-300 ft margin due to altimeter inaccuracy etc to be ok”.
Patrick wrote:
DFS in Germany has recently issued an information note that touches this topic (in German):
The link doesn’t work for me.
In summary, they’re urging VFR pilots to not fully exploit the vertical (and horizontal, for that matter) boundaries of their airspace for various reasons, most notably wake turbulence caused by heavy aircraft potentially just 500 ft above you. They argue that in approach sectors (reverse wedding cakes) the IFR traffic will often by assigned the lowest available flight level, which may be just 500 ft higher than the airspace boundary. The also say (which is no news) they have to report any intrusion to the authorities.All of this can happen in class E as well…I don’t see much room, literally, for the argument “when I fly at the airspace boundary, I can expect a 200-300 ft margin due to altimeter inaccuracy etc to be ok”.
Airborne_Again wrote:
The link doesn’t work for me.
This link should work:
@Peter: There seems to be a bug in the forum software. The following link doesn’t work. The reason seems that the “automatic URL detection” (which converts URL-like strings in postings into hyperlinks) substitutes single quotes in such URLs with another single-quote character, which messes up the hyperlink. Example (click on the link and check the single quotes of the URL in your browser):
