higher. at that altitude it's out of reach of most radar detection. a clear vulnerability. >> i've said that a number of times that it would be pretty simple to take a home-built aircraft down the river, make a left turn over the lincoln memorial and fly it up the mall. it wouldn't be the first time it's been done. >> reporter: in january, a drone crashed on to the white house lawn and in 1994 a small cessna flying low and out of radar's reach came down outside the white house. no one tried to stop that one either. >> it would be relatively simple to create a scenario where you could launch ten gyro copters from ten different airports an hour way from downtown d.c. and fly them at the same time way nasty mission. >> well the argument is hypersensitive radars would trigger countless false alarms detecting things like birds, but one expert said integration of other sensors like noise