Originally Posted by stealth.pilot
Exactly - it is a PCAS so it can tell you if there is a low flying aircraft close by. On the turnpike they sometimes use planes to measure speed, and then have ground cars pull you over further down the road. Obviously radar detector or laser jammer doesn't help with that kind of trap.
Do you have a portable scanner? If so which one? Seems like a good idea to hear police aircraft correspondence.