I,m not saying the K index is crap but why do some birds still get home around the expected velocity and the rest don't , I do believe that the sun and moon in sky at same time causes problems , Today both were up at same time and when I went to let yb s out they sat in loft for more than 10 mins before coming out ? They normally take my head off when I open loft . But to be honest we will never know so can't cancel races just because the atmosphere is dodgy but this is only my thoughts and I,m usually wrong lol.