Contaminated Performance @3mm?

[PEI_3721]

Thanks Sepp; that’s the material I was thinking of.
So the UK CAA ‘suggests’ (not overruling EU OPS) that in the UK wet grooves are not dry, and that UK operators should consider the same throughout Europe ??

The key to the EU case appears to be in the small print – those paved runways which have been specially prepared with grooves or porous pavement and maintained to retain “effectively dry” braking action even when moisture is present.

So exactly how are crews expected to know if a runway is correctly maintained, – perhaps via the runway friction maintenance assessment? But that’s primarily for wet runways, and where the maintenance friction is below a set value, the runway should be declared ‘Slippery when wet’ (NOTAM)
In the absence of operational guidance for the term ‘Slippery when wet’ (it’s the operators responsibility – UK AIP sect AD 1.1.1, para 16), a good working level guide is to use contaminated performance data on a wet ‘Slippery when wet’ runway.

But the discussion is for dry equivalence on a wet grooved runway, so the use of wet data vice dry for reported poor maintenance (on a wet grooved runway) may be insufficient protection because the runway could be ‘Slippery when wet’. Thus, a jump straight to contaminated data might be logical.

I think that this conundrum starts with the use of “effectively dry”. AFAIK, this term is not defined, nor is moisture in CS 25 (origin of performance) and the UK AIP definition differs from EU-OPS (change of colour vs shiny appearance).
So should operators take “effectively dry” a being exactly the same a dry, or perhaps as the UK CAA infers in the FODCOM … there aint no such thing as a ‘dry’ wet grooved runway. But still like the EU, they dump the responsibility back on to the operator, which no doubt falls on the pilot of the day.

As above, IMHO, a wet grooved runway is always wet, and a runway which is ‘Slippery when wet’ is contaminated.
And for a wet runway, how wet is WET – 2.9 mm or 3 mm equivalent? So assess both wet and contaminated data in order to have guidance on the range of likely performance.