Re “…the practicality of the landing performance, it's SOP and is to be followed.” (#9)
Many of the current interpretations of SOPs involve ‘thoughtless’ adherence and is one of the potential problems in landing assessment and other flight operations.
The current FAA guidance (and without thought, the SAFO becomes a rule) requires a minimum distance margin of 15% over any advisory distance.
OLD provides a more realistic baseline on which to judge landing distance, … a judgement, not just a lookup table.
With OLD the airborne distances are longer and the braking action for assumed friction levels may also have been adjusted, but the reported braking action / braking effort to be used, wind, type of runway surface, etc, all require consideration before applying a safety margin. OLD may not consider variability or errors in reporting, thus judgement is required, and additional distance margins added as necessary.
SOPs may provide alleviation for emergency operation, but what is an ‘emergency’, and how might it relate to the expected landing situation; what risks can be justified when landing without a safety margin. SOPs cannot cover every situation; OLD provides a realistic minimum distance for specified conditions and other information to help balance any additional risk during landing.
The comparison of OLD – the required landing distance, with the landing distance available should be a standard procedure of airmanship. Using OLD and the judgement in continuing with a landing should be a rule of mind, but OLD per se isn’t a SOP or rule, the rule is don’t go off the end.