Peter wrote:
150m?
SERA.5005(f): Except when necessary for take-off or landing, or except by permission from the competent authority, a VFR flight shall not be flown:
(1) over the congested areas of cities, towns or settlements or over an open-air assembly of persons at a height less than 300 m (1 000 ft) above the highest obstacle within a radius of 600 m from the aircraft;
(2) elsewhere than as specified in (1), at a height less than 150 m (500 ft) above the ground or water, or 150 m (500 ft) above the highest obstacle within a radius of 150 m (500 ft) from the aircraft
That’s amazing. 150m laterally is very close for planning. MSA flight is planned at obstacle + 1000ft (+2000ft if above 5000ft) and 5nm laterally.
Obviously, in good VMC, you can actually fly 150m to the left of some tower, and that is anyway a legal requirement (the 500ft away from any man made object, loosely speaking, or 500ft away from all objects if in mainland Europe) but that is no good for planning a flight. And a flight must be planned to not bust CAS.
The 1000’ and 2000’ is an IFR requirement IIRC.
Also the 5000’ you refer to is defined differently in the French AIP.
Just got another MOR listing “in the post” 
This is most interesting because it shows an SD log differs from ATC data. The pilot (actually the instructor!) got away with it apparently by having a high-reading (but in spec) TXP
But this pilot didn’t get away with it, presumably because he told ATC he was at 2600ft
AIW? Is this different from CAIT, or just a generic name for it?
I do know one pilot who got a grilling last year from the CAA, the CAA staff was apparently pretty aggressive about it, and his Skydemon track had shown he had not infringed. I don’t remember the circumstances now (whether it was radar airspace (what’s the horizontal accuracy of radar?) or an alleged ATZ infringement that had been “eyeballed”) but understandably the pilot concerned was a bit unhappy with how he had been treated during the process, even if no further action was eventually taken due to the GPS track evidence.
I guess “airspace infringement warning”.
Radar is not all that accurate. Distance is like DME so probably 0.1nm, and azimuth will be less accurate at say 30nm radius. So much worse than GPS. One challenge might be proving that you were getting a decent GPS reception at the time. I don’t know what SD stores in the logs; I would expect stuff like VDOP HDOP etc to be stored.
Who was “CAA staff”, I wonder? Actually I don’t wonder at all; I spoke to him on the phone as written up here and the content of the phone call, had I recorded it, would have been pure dynamite. The CAA pretends there is a whole committee making decisions but other data suggests it is just the one man dishing out the punishments and the committee exists mostly nominally to make it look good. Certainly the numbers (something under 2k a year) could easily be dealt with by the one bloke who is probably on 100k.
I have found that the usual reason for aggression is that you are on bad ground and are trying to bully the other side into a Guilty plea (criminal) or into submission(civil). I used to know a law firm down here which contantly used “bull in a china shop” tactics and mostly got bad deals for its clients. Yet this is 100% the activity of the CAA in this area. And it works because most pilots are like most drivers: they take the less-hassle or the less-cost route.
Not relevant to the UK directly, but I find the whole transition altitude thing a complete pain. In France at least it is all over the place. Gallois mentions 3000 feet but I think at all the airports I’ve been to it’s 5000 or 6000 (in the south where we have a lot of terrain). Presumably as you fly along at 4000 feet you are popping in and out of FL territory and in theory should adjust your altimeter and altitude accordingly – except that there’s absolutely no way of knowing.
Much simpler in the US where it’s true (well, QNH-based) altitude up to 18000 feet whether you’re in Kansas (flat) or Colorado (not flat).
Peter wrote:
The pilot (actually the instructor!) got away with it apparently by having a high-reading (but in spec) TXP
Nope, he did stay in the area where the floor was 3,500ft. The Controler reported “I am not sure he was actually inside CAS, it looked like it was paralleling the line where the base is 2.5A and 3.5A”, and the instructor wrote “reviewed skydemon log which seemed to show that we had come too close, but not infringed”
I wonder what would have happened if the controller had reported a definite infringement (and the ATC tapes whould have shownn that, too) when a GPS log showed he remained outside by 0.001 NM…
hazek wrote:
And you cannot bust a FL boundry if you are at or below the TA, period.
That is exactly the question, is it?
A FL is a pressure altitude, to fly it you don’t really follow an “altitude” at all but you fly over a isobaric pressure level. Hence its height over ground or even over any QNH defined Altitude is variable considerably.
Altitude in general and transition altitude specifically is however based on the pressure level corresponding to the QNH set for the area. So for most purposes other than academic banter it it is pretty much a constant altitude over sea level.
The logic you brought forth and the altimeter setting procedures you quote would suggest that the lower limit of an airspace defined by FL rather than altitude would change at low air pressure as the lower limit would descend through the Transition Altitude. And I agree this makes perfect sense.
Only what if CAA really do not take this into account? Theoretically speaking, a CAS with a lower limit of say FL040 = 4000 ft pressure altitude in an area where the TA would be 3000 ft may very well descend below that or even into the ground. The logical outcome is that in such cases, ATC will not use the levels under TA as they become unusable. That however does not mean they don’t exist, they just fall out of the bottom and consequently can’t be used by ATC. The question therefore would be: Does the formal lower limit of CAS change in such a case?
Posters here suggest that their CAA would go and still call it an infringement if someone penetrates the pressure altitude BELOW the TA just because that is where the lower CAS limit descends to theoretically, then what a lot of people here have been saying can theoretically happen.
The question therefore is, does it? Or is that a hypothetical case which only underlines the apparent fundamental distrust between pilots and their ATC/CAA in the UK?
Mooney_Driver wrote:
The question therefore is, does it? Or is that a hypothetical case
The real problem is just that no one knows how the CAA is going to interpret the lower CAS limit in that situation. We have been told that they don’t take altimeter accuracy, QNH roundoff or transponder encoder roundoff into account – all of which could cause a transponder return to show that the aircraft in inside controlled airspace either when it actually isn’t or when it actually is but the instrument readings available to the pilot shows that it is not.
