Nope
The OC is everything from little school boys, police men and enlisted men sitting in trenches with binoculars... AAA guns, barrage balloons, etc etc... It would be very hard to knock that out.
Hmmm maybe the observer should only be able to see low aircraft, like upto 4000m's... It would also be interesting to know if there could be a chnace the AOC didnt spot anything?