Originally Posted by TCAS FAN
Now is the time to challenge it and get SARG to justify their reasoning/logic? From recent experience with SARG this could be an interesting exercise with a justifiable response not forthcoming.
How come White Waltham get away with a LFA and A/G within the LHR CTR?
Slight thread drift but maybe of interest to some...
Some years ago - probably 20+ now - CAA SRG did research to try to determine metrics for where different levels of ATS were appropriate. They spent quite a lot of money with some external company as I recall, and the results were of little use, mainly because whatever the quantitative results that might be generated by the by the algorithms were said to have huge error bounds because of the variability of the subject. After that, there was some work done internally, using some of the ideas from the external study (perhaps to justify its cost), on an Excel spreadsheet - taking some of the variables such as total movements, busiest day, busiest hour, complexity (number of runways and taxiways), proximity of local airports and others which escape me after all this time - and applying factors to each element to try to rank all UK airports (above a certain size) to see whether there were any outliers in the data, unexpected FIS units amongst all the ATC units, for example. Again, not much of value came of it. Ultimately, the conclusion was that professional judgement was the best approach....although the judgement was to be that of the CAA inspectors - whether these were the best professionals I'll leave to you to decide.
All of this work was done around the time that formal requirements were being introduced for ATC, and to a lesser extent, FIS units - in reality, the work was driven by the introduction of these rules in order to justify their introduction - which made running either ATC or FIS a lot more involved (and arguably while offering no tangible benefits) and, certainly for smaller airports, way more expensive.