Because of the changed security situation and that type of er conflict not being envisaged in the same way now, what we felt was important was to be able to operate er apart from main operating bases, but also from sort of general purpose erm strips, flying clubs and those type of smaller airfields and therefore rather than looking at the damaged runway situation, we looked at the smaller strips and took a length that we could sensibly operate from  erm and took that as the yardstick but clearly  notwithstanding that, there is the prospect of damaged runways and therefore the slight relaxation would also apply to damaged runways but perhaps damaged to a lesser extent.