Considering the effect of high airspeed on distance (table 2), the addition is 30 ft/kt; however the effect of high airspeed on the tendency to float is 250ft/kt. Furthermore, these distances might be additive. Thus it is important to consider the landing distance increase when making approach/threshold speed additives.
thats interesting and from practical point of view not wrong even when i think the official AOM,s do not cover it.
we can say that adding IAS for headwind component improves the risk to float and so by this increases runway lenght needed. thats why a maximum addition is given .
wind is a "strange " thing and may be a pain in the a... when we leave for one moment the paragraphs and performance charts and face real life. hard wind mostly does not come steady. going to slow may result on approach in a hazard when coming to gusts or even microbursts. adding much to vref may results the aircraft is going too fast regarding IAS and simply do not wants to land and floats away.
the regulations say the wind will bled away at tochdown- nice said, but reality may be different. you may encourter severe gusting and sudden direction changes in 3 feet height so you are struggeling to correct as good as possible for a fair and not pretty hard touch and try to keep centreline forgetting that you are floating away.
all that is not covered by any book and it happens fast.
my practise in real heavy and gusting winds is to use as little flaps as possible and to aim to bring the aircraft just down- firm or smooth, who cares.
the me known procedures are to calculate with zero wind and add 50% of the actual wind. when a zero wind landing is possible any headwind should improve margins. but reality is different- thats right.
further it depends on the location and every airport is different- trees, hangars, wind direction , this all affects the gusts, the down and updrafts and much more. i saw 30 kt which were easy and 10 kt which were a real eye opener on flare, no question.
i think when it comes to this theme regulation and standard procedures may differ much from reality, every wind on every airport may be different.
best regards !