3 ms·They won't even know they're there. Small, quiet drones thousands of feet up are practically invisible.by nknighthb 13y agoThey won't even know they're there. Small, quiet drones thousands of feet up are practically invisible.Argorak 13y agoOnce it's known that the police uses such machines, they know that they're there. Don't expect the conclusions to be in any way rational.cma 13y agohe doesn't mean they won't generally be there. he just means that they won't try to erratically avoid specific drones.