@Peter I don’t understand your post.
There are CAS and TMAs starting at 2000ft and possibly at 2500ft. Altitude is flown with QNH on the altimeter and whilst ATC see your altitude on the transponder the PIC doesn’t fly by it.
With regard to error they probably take common sense approach, maybe giving the pilot a warning that he is danger of busting airspace. IIRC altimeter error is 80ft max on the ground check during pre flight.
johnh wrote:
The controller was responsible for separating the IFR traffic from VFR….
In class E?
Peter wrote:
ICAO states that the airspace class of a boundary is that of the less restrictive class. The UK ignores this (without filing an exception to ICAO) and probably other countries do too. Does anyone know about France having filed an exception?
I don’t think the UK ignores it, see CAP 493 (MATS Vol. 1), page 50 (https://www.caa.co.uk/publication/download/20755)
wbardorf wrote:
I don’t think the UK ignores it, see CAP 493 (MATS Vol. 1), page 50 (https://www.caa.co.uk/publication/download/20755)
wbardorf, yes, but they ignore the 200ft margin of error – one of the CAPs showed that if you are 1ft inside the more restrictive AS on your mode-S transponder, they’ll punish you.
arj1 wrote:
wbardorf, yes, but they ignore the 200ft margin of error – one of the CAPs showed that if you are 1ft inside the more restrictive AS on your mode-S transponder, they’ll punish you.
Agreed, whether 2,499 ft or 2,500 ft is inside or outside Class A has little practical implications but wanted to point out that the UK doesn’t differ with respect to more/less restrictive vertical airspace boundaries. Where is the the 200ft margin of error is coming from. I was taught in Germany that e.g. in the Frankfurt airspace region one foot above is technically an incursion but that there would be an accepted tolerance of 100ft or less but not more.
I can’t dig up a reference but the UK did treat the boundary differently, when it came to flying at the base of “airways”. A weird idea, which I remember from my PPL. You had to get an ATC clearance for it.
I’ve heard similar things on the radio around Brussels. Including once where Brussels info informed a plane that they had triggered TCAS on an airliner and gave them a phone number to call. BRU Info told them on frequency they had done nothing wrong, but that they needed the phone call for paperwork.
Other times I’ve heard BRU info kindly but strongly suggest uncontrolled VFR staying lower than the legal limit in certain places due to the particular approach in use at EBBR to eliminate TCAS triggering risks.
This is just meaningless. It’s not a GA pilot responsibility to prevent triggering of TCAS in other aircraft when that GA pilot flies according to airspace and clearances.
Allowable altimeter error in EASA is + or – 60ft or 2 hectopascals(roughly).
I quoted +/- 80ft in a previous post as that was the figure when I did my IR theory many years ago
But I have also seen 75ft quoted but that might be FAA.
Then there is this from the EASA website:-
“If you do have two altimeters, you can’t expect them to show the same as each of them individually has an acceptable error of ±60 feet. (not 50).”
What that means for a PIC and busting airspace I don’t know.
If mode S is showing on the ATCOs screen and s/he thinks that someone might be busting airspace IMO s/he needs to do the calculation based on QNH before they can even think about a bust and then use common sense which is, I am pretty sure what happens in France.
But a word of warning IIRC and perhaps another FFA member can help here. Do they remember a recent missive from the FFA about the floor and ceiling of restricted and prohibited zones which IIRC was the opposite to CAS.
I can’t put my hands on it for the moment.
Just a question under FAA if flight levels don’t start until 18000ft + what information is a mode S transponder in the USA sending with regards to altitude?
Same as anywhere – the pressure altitude.
