Earlier this week I found myself flying the C182 between appointments. I was to the south-east of Benson's MATZ and heading vaguely west.
I had Benson's frequency dialed in, but wasn't talking to them. The police helicopter who was working Benson was given some traffic information. A little while later the police helicopter told the controller that he'd try to get a registration, and a while after that the pilot called to advise of a black and yellow Stearman wearing the number 26 on the fuselage.
From the conversation it seems that the Stearman was in Benson's northern stub, and while it would be good airmanship to be in two-way communication with Benson it is by no means a legal requirement for a civilian aircraft.
So what would you do? My own view is that the police helicopter pilot (or whoever it was on board) was somewhat overzealous in his reporting. If I'm right - and given the controller's lack of real interest in the police helicopter's report I think I am - the Stearman pilot wasn't breaking any rules and hearing one pilot keen to report another leaves a nasty taste in my mouth.