Easiest way would be to paint the runway as if its still but paint it with oils cos they take a while to dry and then blur it with a sponge, cloth or brush. Make sure you wipe in one direction, preferably the opposite way to the flight of the plane. I did one a few years back and it worked well.
Most runways are basicly one colour but try to add different shades and also maybe have it taking off near the landing area where you have all the black rubber tyre skid marks and blur those too.
Hope this helps and lets see some pictures when you have had a go. Best of luck Rob