Originally Posted by
gjhome
On dry runways you may not use more than 60% of the LDA. But do I need to use the 60% margin on wet runway calculations? Or
is it enough to use dry distance * 1,15??
I am only partly trained in this, but straight out of JAR OPS 1:
1.515 Landing - Dry runways allows a full stop landing from 50 ft above the threshold:
(1) For turbo-jet powered aeroplanes, within 60% of the landing distance available;
As a side note, 60% of LDA consumed for landing is definitely not a 60% margin, but that is not the point.
Landing – Wet and contaminated runways (a)... the landing distance available is at least 115% of the required landing distance, determined in accordance with JAR–OPS 1.515.
So, A/C needs 1200 m to stop, with max braking, manufacturers data factored for slope and wind effects.
For dry runway, this 1200 must not represent more than 60% percent of LDA, so the minimum LDA is indeed 2000m - I will call this Required_LD(dry).
If the runway is wet, this RLD(dry) must be increased by 15%, so the minimum LDA(wet) is 2300 m. Agree?
Adding 15% on top of wet makes no sense, as this serves to recalculate RLD(dry) to RDL(wet) and you already start with wet data.
You must use dry table and double factor them to obtain RLD(wet), that is the requirement.
If manufacturer provides you with WET actual LD data, and this ALD(wet) *1/0,6 (with slope and wind) will be shorter than the required RDL(wet) as calculated above, you are allowed to use this shorter minumum LDA.
FD (the un-real)
I am sorry for several editing versions, but that is what really OPS says.