From the very comprehensive and well considered report I could not identify the basis of the published landing data.
Was the AAM based an ‘in house’ computation or did it use Boeing data - performance manual?
Was the QRH based on Boeing ‘actual’ distances, or the more recent OLD method for calculating landing distance?
Would the performance differ between documents, in addition to the likely difference between ‘actual’ and OLD?
Do current documents still show numerical landing weight, where it is difficult to add 15% distance margin, or do they now show actual landing distance, even with the min 15% already added?
General question: re “…15 per cent may be inadequate under certain wet runway conditions and subsequently encouraged operators to apply additional conservatism.”
The FAA SAFO appears to precede the incorporation of TALPA recommendations and the publication of OLD/FOLD by manufacturers. Would the ‘inadequate’ comment still apply to FOLD calculations providing that the correct surface description is used?
Notwithstanding the above, it does not degrade the value of the SAFO remark - need for ‘at least’ or ‘minimum’ of 15% safety factor, particularly as inaccuracies can arise from ground assessment, reporting, or crew interpretation of surface condition or reported braking action.