Radar detectors
I live in a city where the police must get monthly bonuses for handing out speeding tickets. I was coming home and there were 6 patrol cars along the highway awaiting unsuspecting cars. The location they were in seemed pretty easy to spot and would give you enough time to slow down if in fact your were speeding. I found out though that there was an aircraft overhead catching speeders and then radioing down the to the ground. This is something that my trusty radar detector would not pick up and I am glad that this day I was staying within the limits
