On a 12 foot target, that gives plenty of room for error. Besides, a spotter with a view of a known distance on the runway could give a radio call to shoot when the plane reaches that distance. I would try for three seconds before rolloff. The plane would have plenty of speed and a crash would be certain.
Travis is right, that we need to ensure no snipers within two miles of runways.
Using the dynamic components that define the ballistic performance of a projectile, including wind speed, wind direction, temperature, barometric pressure, humidity, range to target, speed of target, movement direction of target, time delay from the spotter's call to the ignition of the propellent...and calculating all of these with in acceptable parameters to allow the shot to be placed on a 12 foot square target...I conceed the shot could be made.