Stefan wrote:
Graeme Cant schrieb:

Lastly is a 100ft or 1000ft violation any different. it is still an
incursion either way you look at it.

No, it isn't. You can't ignore the accuracy of the measuring device.

Yes, it is. If your devices are inaccurate, then it's your
responsibility to add some extra safety margin. Simple as that.

Stefan

Rubbish. When it comes to altitude for ATC purposes - and that's what
the 18k limit is for - the reading on your altimeter is what counts.
Provided it's a legal instrument maintained properly, you fly to the
indications of your altimeter. Asking whether this is "accurate" is
irrelevant and meaningless. If you're told to maintain 18k in a powered
aircraft, what "safety margin" should you allow? Fly at 17750? Fly at
18400? Nonsense!

The OLC's problems arise because the legal device Ramy HAS to use when
he might bust a rule is the altimeter, not the logger. But when he
lands only the LOGGER figure is still there. Ramy was only illegal
though, if he flew over 18k on his ALTIMETER.

The madness of all of this is that the accuracy that Al seems to expect
is not expected by any of the authorities whose rules he claims were
broken. He thinks the whole thing is way more accurate than it is and
way more accurate than any of the real airspace users need it to be.

ATC define en route airways on a radar screen where the defining line is
400 yards wide - with fuzzy edges - and a target takes three sweeps to
cross it!! Al's concept that an airspace boundary is a precision line
in space accurately marked like the painted centreline on a road is
laughable.

So is the idea that a glider's position is measured to an inch by a $200
GPS receiver. Ramy may be 400yards outside a boundary on ATC's scope
but his GPS logger may show him as inside the rhumb line between the
coordinates defining the boundary. Or maybe inside the rhumb line but
outside the Great Circle. Was he wrong or right? If the coordinates
are 100 miles apart, the difference between rhumb line and Great Circle
could be a mile or more and what ATC's scope lines show is probably
neither. He's expected to measure his position by - at best - VOR
radial and DME, not GPS, so there's probably an uncertainty circle about
2 miles in diameter!

What Al wants to do with logger barometric readings and GPS positions is
needed by no other airspace users and the system doesn't work to that
level of accuracy.

GC