LSA LTS CAT I
Tagron/planedrive/Double Hydco
Thanks for your inputs on this issue. The point that I was trying to make was that, perhaps, LSA could promote that a LTS CAT 1 capability exists (if indeed it does!) within the airport’s infrastructure to other operators that may be able to utilise the improvement in RVR minima that might accrue when sea fog affects the airport; prior posts on this forum suggest that RVR minima (due sea fog susceptibility) are more relevant than cloud-base to operations at LSA. Clearly however, this advantage is not available to operators of Airbus equipment for the reasons subsequently outlined (and unknown to me) by planedrive and Double Hydco. However, it should be noted that these restrictions are airframe (specifically Airbus) and Operator (specifically Ezy) related and may not be applicable to other equipment or operators.
I have trawled my browsing history and can’t now find the other references that led me to the Jeppy document I referenced as the latter was clear and concise in comparison with the others, which is why I bookmarked that one; sorry. However, the basic source material is clearly an EU/EASA sponsored regulation.
To back-up my ‘signal quality’ contention a little more, within the UK all Civil CAT I ILS installations are deemed (unless promulgated otherwise) to be capable of providing the required quality of beam structure to enable auto-coupled approaches to be continued below the minimum CAT I Decision Height, subject to the appropriate visual references being achieved at the CAT I limits.
Now, my reasoning went: if ‘normal’ CAT I tolerances allow that capability, then if an ILS installation is commissioned and subsequently maintained to CAT IIIA tolerances (and of course the CAT IIIA limits are far tighter), then presumably it follows that one could conduct an approach to an RVR limit slightly less than the CAT I system limit, supported by a superior ILS signal quality, without compromising safety, which I though was the whole purpose of the LTS CAT I ‘option’. In sum, the CAT IIIA signal has a far better capability of delivering the appropriately equipped and crewed aircraft accurately to the touchdown environment, always provided that the LTS CAT I RVR limits/DH are not busted.
With respect to the 3.5° glideslope on RW05, I’m aware of the CAT II/III requirement to employ only a 3° glideslope. Notwithstanding that, given the previous provision to use an autocoupled CAT I ILS to below CAT I minima, then this must include all CAT I glideslopes above 3° up to a maximum of 3.5° of which there are a number within the UK. Consequently, conducting an autocoupled approach to below CAT I minima (subject to required visual references being achieved at DH) on glidepaths above 3° is currently permitted. However, I fully agree that it might be prudent to examine glideslope angles above 3° rather more carefully on a case by case basis.
To be clear, I’m NOT advocating conducting inappropriate ‘CAT III’ operations; heaven forbid! However, subject to suitable ground infrastructure, aircraft fits and recurrent training validity, then it seems entirely reasonable for an approach to be continued in the slightly lower RVR conditions with the expectation that the aircraft will be delivered to a position where a safe landing can be effected. I only intended to stimulate thought and debate here – I suspect that LSA will have got the ‘Horse’s mouth word’ from the Regulator, but of course we’re not privy to what that might have been!