most states don't even use helicopters to look for crops, there is much much much much to much land to ever thourally cover with a bird, they would spend millions and find very little, so they reserve them for very high traffic areas where growers are known to be every year like mendicino and humbolt, police run a business, they wont spend there budget on anything that wont yeild them seizures and arrests, because thats how they convince the state they deserve more money. if they spend their whole budget on heli gas and brought back 20 spindly plants they would be in a lot of trouble. most places the cops are about as clueless to growers as the general public, and as long as you look like you have a reason to be there nobody will give you any trouble. most heli's you see flying low are fogging mosquitoes, taking arial photos and other legitimate things but are mistaken by paranoid stoners to be the dea on the hunt.
i have had crops found by stupid geocachers twice, once stolen, once reported to cops who took my fencing, plants and grow bags, but left me with the rootballs. i have never been caught, but you will be hard pressed to catch me doing anything in the woods, im very quiet, don't leave trails, and listen very well, being part of nature when your in it rather than a noisy trespasser of nature will help you avoid most all contact.