AerocatS2A, thanks, interesting.
The AFM text appears to follow JAR-OPS 1.457(d) and thence with EU-OPS 1.475(d) which to my further surprise still states -
“For performance purposes, a damp runway, other than a grass runway, may be considered to be dry”. The 146 was a UK CAA / JAR aircraft, and it is quite possible that it included operational regulations. Thus the 146 was in accordance with JAR-OPS and remains so with EU-OPS.
Although BAe equate damp with dry, there is no guidance as to what additional risk is involved. Presumably the performance reduction from damp does not warrant the additional 1.15 ‘wet’ factor, but equally damp is not as good as ‘dry’. Operators are left to judge any additional risk and employ suitable mitigation.
The UK CAA (#3) may have attempted to clarify the situation, but without specifically including damp, the ‘damp’ ambiguity remains; i.e. EU-OPS damp may be considered dry – but not as good as dry, but wet grooved is not effectively dry (UK CAA); but is wet grooved as good as damp ?
- EU-OPS states that damp is ‘effectively dry’;
- FAA / NASA / ESDU research states that damp is not as good as dry;
- the UK CAA state that wet grooved is not ‘effectively dry’;
- some manufacturers state the operational requirements,
- but no one states what the additional risks are and what mitigation might be assumed in the regulations.
So what happens if other operational regulations do not agree with EU-OPS (e.g FAR 121).
Would the originating AFM overrule FAR, or would the national authority remove the damp caveat in their version of the AFM ?
Thus full circle to the original question.