Some parts of the article are OK but some less.
One paragraph complains that ATCO no longer have any discretion to not report minor infringements. So it complain that subjectivity has been removed.
The next paragraph complains that human subjectivity is present in MOR reporting.
The bit on altimetry is not really worth the ink or electrons.
The first point is right, the other have either no effect on infringements or are the sum or points previously reported.
The whole idea that CAIT should allow 400ft margin was a funny joke. Does Pilot magazine really want all control airspace base to come down by 400ft (rounded to 500ft)?
Xtophe wrote:
The whole idea that CAIT should allow 400ft margin was a funny joke. Does Pilot magazine really want all control airspace base to come down by 400ft (rounded to 500ft)?
Given that there are tolerances for altimeter accuracy, I had always assumed that the airspace was designed with safety margins already incorporated. Is this something that has been forgotten, or something that nobody ever considered in the first place?
I’m not sure that I follow your objections to the section on altimetry. They seem reasonable points to me. Can you expound?
Also found this leaflet local copy on the European MOR portal
The last page of the leaflet / left-had half of the 1st page of PDF is a bit disconnected to the CAA practice.
kwlf wrote:
I’m not sure that I follow your objections to the section on altimetry. They seem reasonable points to me. Can you expound?
Error in the static system: If the same static system is used by altimeter and transponder and we don’t consider the encoder error (which I accept), the transponder and altimeter will read the same. That same value is potentially false but is the same. So it has no influence on CAIT and friends.
Some manufacturer’s continued airworthiness requirements do not require any repetitive checks.
Implying that it is normal to let an encoder drift out-of-spec. That the exact opposite. Some encoder or some transponder with integrated encoder manufacturer have demonstrated to the certifying authority that their design is robust and won’t loose calibration hence that statement.
ASE: I haven’t dig enough but really smell of a value out of context.
Will you start a flight if sitting on the apron after setting QNH from the ATIS, you see a 250ft difference between your altimeter and the airfield elevation?
That 245ft is very likely to already contain the 125ft (encoder) transponder error.
From the article
The transponder may not even be connected to the same static source as the altimeter. Some take their pressure from behind the panel, others from their own static source. Wherever it originates, the accuracy of the static pressure provided to the transponder at varying airspeeds and attitudes, including yaw, is never measured in GA aircraft.
I don’t know how common that is, but it isn’t as if the point wasn’t covered. Perhaps mode A transponders are being replaced with C/S transponders without them being connected up in the interests of expedience, as this would involve tapping into the static system and all the messiness and risks of screwing something up that entails.
I find the idea that nobody looks at the effects of yaw on static error alarming… unless that is only for VFR types in which case this is a non-issue. Can you really certify an aircraft for IFR flight without measuring such things?
I know that it’s a common error on my type (the pitot static are very close) that leads to different altimeter readings at speed. I think I checked it a long time ago on a long runway, but it’s worth double checking. I never thought of relating it to the bust ’em policy.
However, what ATC see (and what gets you busted) is the altitude encoder value, and that should be plumbed into the same pipework as any altimeter, so if there is an altimetry error due to speed, nobody will be in a position to notice it.
The only way you would realise it is by watching the GPS altitude, but very few people do that.
One paragraph complains that ATCO no longer have any discretion to not report minor infringements. So it complain that subjectivity has been removed.
The next paragraph complains that human subjectivity is present in MOR reporting.
Both are probably true. It is obvious from reading the MORs that a lot more effort goes into some of them than into others. Whether that makes a difference to who gets busted, I don’t know. The standard form of the CAA letter is that “X has been appointed executor on a MOR…” which is a ridiculous form of wording (which no normal civilised person would have chosen) and is clearly intended to sound like you are getting sent to the guillotine 
Xtophe wrote:
ASE: I haven’t dig enough but really smell of a value out of context.
ASE is the maximum difference between the indication and the actual altitude. So yes: it is already including all possible errors.
kwlf wrote:
Given that there are tolerances for altimeter accuracy, I had always assumed that the airspace was designed with safety margins already incorporated. Is this something that has been forgotten, or something that nobody ever considered in the first place?
The question (as always with safety margins) is: Who is allowed to eat up those margins?
“Everyone knows that my plane can indicated 250ft off so I should not be punished if I infringe less than 250ft” is only one possible perspective to look tat that problem. Another one (equally valid but obviously not that popular amongst pilots) would be “Everyone knows that my plane can indicate 250ft off so I should stay aways at least 250ft indicated from every airspace so that I’m on the safe side” …
